Merging upstream version 1.68.2+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

358 files changed, 9706 insertions, 0 deletions

diff --git a/tests/ui/feature-gates/allow-features-empty.rs b/tests/ui/feature-gates/allow-features-empty.rs
new file mode 100644
index 000000000..88a609349
--- /dev/null
+++ b/tests/ui/feature-gates/allow-features-empty.rs
@@ -0,0 +1,8 @@
+// compile-flags: -Z allow_features=
+// Note: This test uses rustc internal flags because they will never stabilize.
+
+#![feature(lang_items)] //~ ERROR
+
+#![feature(unknown_stdlib_feature)] //~ ERROR
+
+fn main() {}
diff --git a/tests/ui/feature-gates/allow-features-empty.stderr b/tests/ui/feature-gates/allow-features-empty.stderr
new file mode 100644
index 000000000..f88b3ea0a
--- /dev/null
+++ b/tests/ui/feature-gates/allow-features-empty.stderr
@@ -0,0 +1,15 @@
+error[E0725]: the feature `lang_items` is not in the list of allowed features
+  --> $DIR/allow-features-empty.rs:4:12
+   |
+LL | #![feature(lang_items)]
+   |            ^^^^^^^^^^
+
+error[E0725]: the feature `unknown_stdlib_feature` is not in the list of allowed features
+  --> $DIR/allow-features-empty.rs:6:12
+   |
+LL | #![feature(unknown_stdlib_feature)]
+   |            ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0725`.
diff --git a/tests/ui/feature-gates/allow-features.rs b/tests/ui/feature-gates/allow-features.rs
new file mode 100644
index 000000000..2ce4701a8
--- /dev/null
+++ b/tests/ui/feature-gates/allow-features.rs
@@ -0,0 +1,8 @@
+// compile-flags: -Z allow_features=lang_items
+// Note: This test uses rustc internal flags because they will never stabilize.
+
+#![feature(lang_items)]
+
+#![feature(unknown_stdlib_feature)] //~ ERROR
+
+fn main() {}
diff --git a/tests/ui/feature-gates/allow-features.stderr b/tests/ui/feature-gates/allow-features.stderr
new file mode 100644
index 000000000..9caf48dd1
--- /dev/null
+++ b/tests/ui/feature-gates/allow-features.stderr
@@ -0,0 +1,9 @@
+error[E0725]: the feature `unknown_stdlib_feature` is not in the list of allowed features
+  --> $DIR/allow-features.rs:6:12
+   |
+LL | #![feature(unknown_stdlib_feature)]
+   |            ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0725`.
diff --git a/tests/ui/feature-gates/auxiliary/cfg-target-thread-local.rs b/tests/ui/feature-gates/auxiliary/cfg-target-thread-local.rs
new file mode 100644
index 000000000..bd5c8f81c
--- /dev/null
+++ b/tests/ui/feature-gates/auxiliary/cfg-target-thread-local.rs
@@ -0,0 +1,7 @@
+#![feature(thread_local)]
+#![feature(cfg_target_thread_local)]
+#![crate_type = "lib"]
+
+#[no_mangle]
+#[cfg_attr(target_thread_local, thread_local)]
+pub static FOO: u32 = 3;
diff --git a/tests/ui/feature-gates/auxiliary/debugger-visualizer.natvis b/tests/ui/feature-gates/auxiliary/debugger-visualizer.natvis
new file mode 100644
index 000000000..6eb47e3d8
--- /dev/null
+++ b/tests/ui/feature-gates/auxiliary/debugger-visualizer.natvis
@@ -0,0 +1,3 @@
+<?xml version="1.0" encoding="utf-8"?>
+<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
+</AutoVisualizer>
diff --git a/tests/ui/feature-gates/auxiliary/pub_dep.rs b/tests/ui/feature-gates/auxiliary/pub_dep.rs
new file mode 100644
index 000000000..3ebafd953
--- /dev/null
+++ b/tests/ui/feature-gates/auxiliary/pub_dep.rs
@@ -0,0 +1 @@
+pub struct PubType;
diff --git a/tests/ui/feature-gates/auxiliary/re_rebalance_coherence_lib.rs b/tests/ui/feature-gates/auxiliary/re_rebalance_coherence_lib.rs
new file mode 100644
index 000000000..41b9d64d5
--- /dev/null
+++ b/tests/ui/feature-gates/auxiliary/re_rebalance_coherence_lib.rs
@@ -0,0 +1,22 @@
+pub trait Backend {}
+pub trait SupportsDefaultKeyword {}
+
+impl SupportsDefaultKeyword for Postgres {}
+
+pub struct Postgres;
+
+impl Backend for Postgres {}
+
+pub struct AstPass<DB>(::std::marker::PhantomData<DB>);
+
+pub trait QueryFragment<DB: Backend> {}
+
+
+#[derive(Debug, Clone, Copy)]
+pub struct BatchInsert<'a, T: 'a, Tab> {
+    _marker: ::std::marker::PhantomData<(&'a T, Tab)>,
+}
+
+impl<'a, T:'a, Tab, DB> QueryFragment<DB> for BatchInsert<'a, T, Tab>
+where DB: SupportsDefaultKeyword + Backend,
+{}
diff --git a/tests/ui/feature-gates/bench.rs b/tests/ui/feature-gates/bench.rs
new file mode 100644
index 000000000..8de390bec
--- /dev/null
+++ b/tests/ui/feature-gates/bench.rs
@@ -0,0 +1,9 @@
+// edition:2018
+
+#[bench] //~ ERROR use of unstable library feature 'test'
+         //~| WARN this was previously accepted
+fn bench() {}
+
+use bench as _; //~ ERROR use of unstable library feature 'test'
+                //~| WARN this was previously accepted
+fn main() {}
diff --git a/tests/ui/feature-gates/bench.stderr b/tests/ui/feature-gates/bench.stderr
new file mode 100644
index 000000000..5f0aaf925
--- /dev/null
+++ b/tests/ui/feature-gates/bench.stderr
@@ -0,0 +1,21 @@
+error: use of unstable library feature 'test': `bench` is a part of custom test frameworks which are unstable
+  --> $DIR/bench.rs:3:3
+   |
+LL | #[bench]
+   |   ^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #64266 <https://github.com/rust-lang/rust/issues/64266>
+   = note: `#[deny(soft_unstable)]` on by default
+
+error: use of unstable library feature 'test': `bench` is a part of custom test frameworks which are unstable
+  --> $DIR/bench.rs:7:5
+   |
+LL | use bench as _;
+   |     ^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #64266 <https://github.com/rust-lang/rust/issues/64266>
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/feature-gates/duplicate-features.rs b/tests/ui/feature-gates/duplicate-features.rs
new file mode 100644
index 000000000..d8f781805
--- /dev/null
+++ b/tests/ui/feature-gates/duplicate-features.rs
@@ -0,0 +1,9 @@
+#![allow(stable_features)]
+
+#![feature(rust1)]
+#![feature(rust1)] //~ ERROR the feature `rust1` has already been declared
+
+#![feature(if_let)]
+#![feature(if_let)] //~ ERROR the feature `if_let` has already been declared
+
+fn main() {}
diff --git a/tests/ui/feature-gates/duplicate-features.stderr b/tests/ui/feature-gates/duplicate-features.stderr
new file mode 100644
index 000000000..dbde806f6
--- /dev/null
+++ b/tests/ui/feature-gates/duplicate-features.stderr
@@ -0,0 +1,15 @@
+error[E0636]: the feature `if_let` has already been declared
+  --> $DIR/duplicate-features.rs:7:12
+   |
+LL | #![feature(if_let)]
+   |            ^^^^^^
+
+error[E0636]: the feature `rust1` has already been declared
+  --> $DIR/duplicate-features.rs:4:12
+   |
+LL | #![feature(rust1)]
+   |            ^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0636`.
diff --git a/tests/ui/feature-gates/feature-gate-abi-avr-interrupt.rs b/tests/ui/feature-gates/feature-gate-abi-avr-interrupt.rs
new file mode 100644
index 000000000..05461297a
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi-avr-interrupt.rs
@@ -0,0 +1,51 @@
+// needs-llvm-components: avr
+// compile-flags: --target=avr-unknown-gnu-atmega328 --crate-type=rlib
+#![no_core]
+#![feature(no_core, lang_items)]
+#[lang="sized"]
+trait Sized { }
+
+// Test that the AVR interrupt ABI cannot be used when avr_interrupt
+// feature gate is not used.
+
+extern "avr-non-blocking-interrupt" fn fu() {}
+//~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+extern "avr-interrupt" fn f() {}
+//~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+
+trait T {
+    extern "avr-interrupt" fn m();
+    //~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+    extern "avr-non-blocking-interrupt" fn mu();
+    //~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+
+    extern "avr-interrupt" fn dm() {}
+    //~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+    extern "avr-non-blocking-interrupt" fn dmu() {}
+    //~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+}
+
+struct S;
+impl T for S {
+    extern "avr-interrupt" fn m() {}
+    //~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+    extern "avr-non-blocking-interrupt" fn mu() {}
+    //~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+}
+
+impl S {
+    extern "avr-interrupt" fn im() {}
+    //~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+    extern "avr-non-blocking-interrupt" fn imu() {}
+    //~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+}
+
+type TA = extern "avr-interrupt" fn();
+//~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+type TAU = extern "avr-non-blocking-interrupt" fn();
+//~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+
+extern "avr-interrupt" {}
+//~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
+extern "avr-non-blocking-interrupt" {}
+//~^ ERROR avr-interrupt and avr-non-blocking-interrupt ABIs are experimental
diff --git a/tests/ui/feature-gates/feature-gate-abi-avr-interrupt.stderr b/tests/ui/feature-gates/feature-gate-abi-avr-interrupt.stderr
new file mode 100644
index 000000000..d017d03a3
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi-avr-interrupt.stderr
@@ -0,0 +1,129 @@
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:11:8
+   |
+LL | extern "avr-non-blocking-interrupt" fn fu() {}
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:13:8
+   |
+LL | extern "avr-interrupt" fn f() {}
+   |        ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:17:12
+   |
+LL |     extern "avr-interrupt" fn m();
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:19:12
+   |
+LL |     extern "avr-non-blocking-interrupt" fn mu();
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:22:12
+   |
+LL |     extern "avr-interrupt" fn dm() {}
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:24:12
+   |
+LL |     extern "avr-non-blocking-interrupt" fn dmu() {}
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:30:12
+   |
+LL |     extern "avr-interrupt" fn m() {}
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:32:12
+   |
+LL |     extern "avr-non-blocking-interrupt" fn mu() {}
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:37:12
+   |
+LL |     extern "avr-interrupt" fn im() {}
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:39:12
+   |
+LL |     extern "avr-non-blocking-interrupt" fn imu() {}
+   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:43:18
+   |
+LL | type TA = extern "avr-interrupt" fn();
+   |                  ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:45:19
+   |
+LL | type TAU = extern "avr-non-blocking-interrupt" fn();
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:48:8
+   |
+LL | extern "avr-interrupt" {}
+   |        ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error[E0658]: avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi-avr-interrupt.rs:50:8
+   |
+LL | extern "avr-non-blocking-interrupt" {}
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69664 <https://github.com/rust-lang/rust/issues/69664> for more information
+   = help: add `#![feature(abi_avr_interrupt)]` to the crate attributes to enable
+
+error: aborting due to 14 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-abi-msp430-interrupt.rs b/tests/ui/feature-gates/feature-gate-abi-msp430-interrupt.rs
new file mode 100644
index 000000000..8b7d8066a
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi-msp430-interrupt.rs
@@ -0,0 +1,34 @@
+// needs-llvm-components: msp430
+// compile-flags: --target=msp430-none-elf --crate-type=rlib
+#![no_core]
+#![feature(no_core, lang_items)]
+#[lang="sized"]
+trait Sized { }
+
+extern "msp430-interrupt" fn f() {}
+//~^ ERROR msp430-interrupt ABI is experimental
+
+trait T {
+    extern "msp430-interrupt" fn m();
+    //~^ ERROR msp430-interrupt ABI is experimental
+
+    extern "msp430-interrupt" fn dm() {}
+    //~^ ERROR msp430-interrupt ABI is experimental
+}
+
+struct S;
+impl T for S {
+    extern "msp430-interrupt" fn m() {}
+    //~^ ERROR msp430-interrupt ABI is experimental
+}
+
+impl S {
+    extern "msp430-interrupt" fn im() {}
+    //~^ ERROR msp430-interrupt ABI is experimental
+}
+
+type TA = extern "msp430-interrupt" fn();
+//~^ ERROR msp430-interrupt ABI is experimental
+
+extern "msp430-interrupt" {}
+//~^ ERROR msp430-interrupt ABI is experimental
diff --git a/tests/ui/feature-gates/feature-gate-abi-msp430-interrupt.stderr b/tests/ui/feature-gates/feature-gate-abi-msp430-interrupt.stderr
new file mode 100644
index 000000000..c19ec9789
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi-msp430-interrupt.stderr
@@ -0,0 +1,66 @@
+error[E0658]: msp430-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-msp430-interrupt.rs:8:8
+   |
+LL | extern "msp430-interrupt" fn f() {}
+   |        ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #38487 <https://github.com/rust-lang/rust/issues/38487> for more information
+   = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
+
+error[E0658]: msp430-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-msp430-interrupt.rs:12:12
+   |
+LL |     extern "msp430-interrupt" fn m();
+   |            ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #38487 <https://github.com/rust-lang/rust/issues/38487> for more information
+   = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
+
+error[E0658]: msp430-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-msp430-interrupt.rs:15:12
+   |
+LL |     extern "msp430-interrupt" fn dm() {}
+   |            ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #38487 <https://github.com/rust-lang/rust/issues/38487> for more information
+   = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
+
+error[E0658]: msp430-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-msp430-interrupt.rs:21:12
+   |
+LL |     extern "msp430-interrupt" fn m() {}
+   |            ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #38487 <https://github.com/rust-lang/rust/issues/38487> for more information
+   = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
+
+error[E0658]: msp430-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-msp430-interrupt.rs:26:12
+   |
+LL |     extern "msp430-interrupt" fn im() {}
+   |            ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #38487 <https://github.com/rust-lang/rust/issues/38487> for more information
+   = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
+
+error[E0658]: msp430-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-msp430-interrupt.rs:30:18
+   |
+LL | type TA = extern "msp430-interrupt" fn();
+   |                  ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #38487 <https://github.com/rust-lang/rust/issues/38487> for more information
+   = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
+
+error[E0658]: msp430-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-msp430-interrupt.rs:33:8
+   |
+LL | extern "msp430-interrupt" {}
+   |        ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #38487 <https://github.com/rust-lang/rust/issues/38487> for more information
+   = help: add `#![feature(abi_msp430_interrupt)]` to the crate attributes to enable
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-abi-x86-interrupt.rs b/tests/ui/feature-gates/feature-gate-abi-x86-interrupt.rs
new file mode 100644
index 000000000..7c3e4d10d
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi-x86-interrupt.rs
@@ -0,0 +1,28 @@
+// needs-llvm-components: x86
+// compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=rlib
+#![no_core]
+#![feature(no_core, lang_items)]
+#[lang="sized"]
+trait Sized { }
+
+extern "x86-interrupt" fn f7() {} //~ ERROR x86-interrupt ABI is experimental
+trait Tr {
+    extern "x86-interrupt" fn m7(); //~ ERROR x86-interrupt ABI is experimental
+    extern "x86-interrupt" fn dm7() {} //~ ERROR x86-interrupt ABI is experimental
+}
+
+struct S;
+
+// Methods in trait impl
+impl Tr for S {
+    extern "x86-interrupt" fn m7() {} //~ ERROR x86-interrupt ABI is experimental
+}
+
+// Methods in inherent impl
+impl S {
+    extern "x86-interrupt" fn im7() {} //~ ERROR x86-interrupt ABI is experimental
+}
+
+type A7 = extern "x86-interrupt" fn(); //~ ERROR x86-interrupt ABI is experimental
+
+extern "x86-interrupt" {} //~ ERROR x86-interrupt ABI is experimental
diff --git a/tests/ui/feature-gates/feature-gate-abi-x86-interrupt.stderr b/tests/ui/feature-gates/feature-gate-abi-x86-interrupt.stderr
new file mode 100644
index 000000000..3b727a745
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi-x86-interrupt.stderr
@@ -0,0 +1,66 @@
+error[E0658]: x86-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-x86-interrupt.rs:8:8
+   |
+LL | extern "x86-interrupt" fn f7() {}
+   |        ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #40180 <https://github.com/rust-lang/rust/issues/40180> for more information
+   = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
+
+error[E0658]: x86-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-x86-interrupt.rs:10:12
+   |
+LL |     extern "x86-interrupt" fn m7();
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #40180 <https://github.com/rust-lang/rust/issues/40180> for more information
+   = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
+
+error[E0658]: x86-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-x86-interrupt.rs:11:12
+   |
+LL |     extern "x86-interrupt" fn dm7() {}
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #40180 <https://github.com/rust-lang/rust/issues/40180> for more information
+   = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
+
+error[E0658]: x86-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-x86-interrupt.rs:18:12
+   |
+LL |     extern "x86-interrupt" fn m7() {}
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #40180 <https://github.com/rust-lang/rust/issues/40180> for more information
+   = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
+
+error[E0658]: x86-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-x86-interrupt.rs:23:12
+   |
+LL |     extern "x86-interrupt" fn im7() {}
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #40180 <https://github.com/rust-lang/rust/issues/40180> for more information
+   = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
+
+error[E0658]: x86-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-x86-interrupt.rs:26:18
+   |
+LL | type A7 = extern "x86-interrupt" fn();
+   |                  ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #40180 <https://github.com/rust-lang/rust/issues/40180> for more information
+   = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
+
+error[E0658]: x86-interrupt ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi-x86-interrupt.rs:28:8
+   |
+LL | extern "x86-interrupt" {}
+   |        ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #40180 <https://github.com/rust-lang/rust/issues/40180> for more information
+   = help: add `#![feature(abi_x86_interrupt)]` to the crate attributes to enable
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-abi.rs b/tests/ui/feature-gates/feature-gate-abi.rs
new file mode 100644
index 000000000..712655f97
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi.rs
@@ -0,0 +1,60 @@
+// gate-test-intrinsics
+// gate-test-platform_intrinsics
+// compile-flags: --crate-type=rlib
+
+#![feature(no_core, lang_items)]
+#![no_core]
+
+#[lang="sized"]
+trait Sized { }
+
+#[lang="tuple_trait"]
+trait Tuple { }
+
+// Functions
+extern "rust-intrinsic" fn f1() {} //~ ERROR intrinsics are subject to change
+                                   //~^ ERROR intrinsic must be in
+extern "platform-intrinsic" fn f2() {} //~ ERROR platform intrinsics are experimental
+                                       //~^ ERROR intrinsic must be in
+extern "rust-call" fn f4(_: ()) {} //~ ERROR rust-call ABI is subject to change
+
+// Methods in trait definition
+trait Tr {
+    extern "rust-intrinsic" fn m1(); //~ ERROR intrinsics are subject to change
+                                     //~^ ERROR intrinsic must be in
+    extern "platform-intrinsic" fn m2(); //~ ERROR platform intrinsics are experimental
+                                         //~^ ERROR intrinsic must be in
+    extern "rust-call" fn m4(_: ()); //~ ERROR rust-call ABI is subject to change
+
+    extern "rust-call" fn dm4(_: ()) {} //~ ERROR rust-call ABI is subject to change
+}
+
+struct S;
+
+// Methods in trait impl
+impl Tr for S {
+    extern "rust-intrinsic" fn m1() {} //~ ERROR intrinsics are subject to change
+                                       //~^ ERROR intrinsic must be in
+    extern "platform-intrinsic" fn m2() {} //~ ERROR platform intrinsics are experimental
+                                           //~^ ERROR intrinsic must be in
+    extern "rust-call" fn m4(_: ()) {} //~ ERROR rust-call ABI is subject to change
+}
+
+// Methods in inherent impl
+impl S {
+    extern "rust-intrinsic" fn im1() {} //~ ERROR intrinsics are subject to change
+                                        //~^ ERROR intrinsic must be in
+    extern "platform-intrinsic" fn im2() {} //~ ERROR platform intrinsics are experimental
+                                            //~^ ERROR intrinsic must be in
+    extern "rust-call" fn im4(_: ()) {} //~ ERROR rust-call ABI is subject to change
+}
+
+// Function pointer types
+type A1 = extern "rust-intrinsic" fn(); //~ ERROR intrinsics are subject to change
+type A2 = extern "platform-intrinsic" fn(); //~ ERROR platform intrinsics are experimental
+type A4 = extern "rust-call" fn(_: ()); //~ ERROR rust-call ABI is subject to change
+
+// Foreign modules
+extern "rust-intrinsic" {} //~ ERROR intrinsics are subject to change
+extern "platform-intrinsic" {} //~ ERROR platform intrinsics are experimental
+extern "rust-call" {} //~ ERROR rust-call ABI is subject to change
diff --git a/tests/ui/feature-gates/feature-gate-abi.stderr b/tests/ui/feature-gates/feature-gate-abi.stderr
new file mode 100644
index 000000000..e9791b951
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi.stderr
@@ -0,0 +1,216 @@
+error[E0658]: intrinsics are subject to change
+  --> $DIR/feature-gate-abi.rs:15:8
+   |
+LL | extern "rust-intrinsic" fn f1() {}
+   |        ^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(intrinsics)]` to the crate attributes to enable
+
+error[E0658]: platform intrinsics are experimental and possibly buggy
+  --> $DIR/feature-gate-abi.rs:17:8
+   |
+LL | extern "platform-intrinsic" fn f2() {}
+   |        ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #27731 <https://github.com/rust-lang/rust/issues/27731> for more information
+   = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
+
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-abi.rs:19:8
+   |
+LL | extern "rust-call" fn f4(_: ()) {}
+   |        ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: intrinsics are subject to change
+  --> $DIR/feature-gate-abi.rs:23:12
+   |
+LL |     extern "rust-intrinsic" fn m1();
+   |            ^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(intrinsics)]` to the crate attributes to enable
+
+error[E0658]: platform intrinsics are experimental and possibly buggy
+  --> $DIR/feature-gate-abi.rs:25:12
+   |
+LL |     extern "platform-intrinsic" fn m2();
+   |            ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #27731 <https://github.com/rust-lang/rust/issues/27731> for more information
+   = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
+
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-abi.rs:27:12
+   |
+LL |     extern "rust-call" fn m4(_: ());
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-abi.rs:29:12
+   |
+LL |     extern "rust-call" fn dm4(_: ()) {}
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: intrinsics are subject to change
+  --> $DIR/feature-gate-abi.rs:36:12
+   |
+LL |     extern "rust-intrinsic" fn m1() {}
+   |            ^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(intrinsics)]` to the crate attributes to enable
+
+error[E0658]: platform intrinsics are experimental and possibly buggy
+  --> $DIR/feature-gate-abi.rs:38:12
+   |
+LL |     extern "platform-intrinsic" fn m2() {}
+   |            ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #27731 <https://github.com/rust-lang/rust/issues/27731> for more information
+   = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
+
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-abi.rs:40:12
+   |
+LL |     extern "rust-call" fn m4(_: ()) {}
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: intrinsics are subject to change
+  --> $DIR/feature-gate-abi.rs:45:12
+   |
+LL |     extern "rust-intrinsic" fn im1() {}
+   |            ^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(intrinsics)]` to the crate attributes to enable
+
+error[E0658]: platform intrinsics are experimental and possibly buggy
+  --> $DIR/feature-gate-abi.rs:47:12
+   |
+LL |     extern "platform-intrinsic" fn im2() {}
+   |            ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #27731 <https://github.com/rust-lang/rust/issues/27731> for more information
+   = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
+
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-abi.rs:49:12
+   |
+LL |     extern "rust-call" fn im4(_: ()) {}
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: intrinsics are subject to change
+  --> $DIR/feature-gate-abi.rs:53:18
+   |
+LL | type A1 = extern "rust-intrinsic" fn();
+   |                  ^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(intrinsics)]` to the crate attributes to enable
+
+error[E0658]: platform intrinsics are experimental and possibly buggy
+  --> $DIR/feature-gate-abi.rs:54:18
+   |
+LL | type A2 = extern "platform-intrinsic" fn();
+   |                  ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #27731 <https://github.com/rust-lang/rust/issues/27731> for more information
+   = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
+
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-abi.rs:55:18
+   |
+LL | type A4 = extern "rust-call" fn(_: ());
+   |                  ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: intrinsics are subject to change
+  --> $DIR/feature-gate-abi.rs:58:8
+   |
+LL | extern "rust-intrinsic" {}
+   |        ^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(intrinsics)]` to the crate attributes to enable
+
+error[E0658]: platform intrinsics are experimental and possibly buggy
+  --> $DIR/feature-gate-abi.rs:59:8
+   |
+LL | extern "platform-intrinsic" {}
+   |        ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #27731 <https://github.com/rust-lang/rust/issues/27731> for more information
+   = help: add `#![feature(platform_intrinsics)]` to the crate attributes to enable
+
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-abi.rs:60:8
+   |
+LL | extern "rust-call" {}
+   |        ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
+  --> $DIR/feature-gate-abi.rs:23:32
+   |
+LL |     extern "rust-intrinsic" fn m1();
+   |                                ^^
+
+error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
+  --> $DIR/feature-gate-abi.rs:25:36
+   |
+LL |     extern "platform-intrinsic" fn m2();
+   |                                    ^^
+
+error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
+  --> $DIR/feature-gate-abi.rs:15:33
+   |
+LL | extern "rust-intrinsic" fn f1() {}
+   |                                 ^^
+
+error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
+  --> $DIR/feature-gate-abi.rs:17:37
+   |
+LL | extern "platform-intrinsic" fn f2() {}
+   |                                     ^^
+
+error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
+  --> $DIR/feature-gate-abi.rs:36:37
+   |
+LL |     extern "rust-intrinsic" fn m1() {}
+   |                                     ^^
+
+error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
+  --> $DIR/feature-gate-abi.rs:38:41
+   |
+LL |     extern "platform-intrinsic" fn m2() {}
+   |                                         ^^
+
+error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
+  --> $DIR/feature-gate-abi.rs:45:38
+   |
+LL |     extern "rust-intrinsic" fn im1() {}
+   |                                      ^^
+
+error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
+  --> $DIR/feature-gate-abi.rs:47:42
+   |
+LL |     extern "platform-intrinsic" fn im2() {}
+   |                                          ^^
+
+error: aborting due to 27 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-abi_amdgpu_kernel.rs b/tests/ui/feature-gates/feature-gate-abi_amdgpu_kernel.rs
new file mode 100644
index 000000000..465b81d7f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi_amdgpu_kernel.rs
@@ -0,0 +1,30 @@
+// compile-flags: --crate-type=rlib
+#![no_core]
+#![feature(no_core, lang_items)]
+#[lang="sized"]
+trait Sized { }
+
+extern "amdgpu-kernel" fn fu() {} //~ ERROR amdgpu-kernel ABI is experimental
+//~^ ERROR is not a supported ABI
+
+trait T {
+    extern "amdgpu-kernel" fn mu(); //~ ERROR amdgpu-kernel ABI is experimental
+    extern "amdgpu-kernel" fn dmu() {} //~ ERROR amdgpu-kernel ABI is experimental
+    //~^ ERROR is not a supported ABI
+}
+
+struct S;
+impl T for S {
+    extern "amdgpu-kernel" fn mu() {} //~ ERROR amdgpu-kernel ABI is experimental
+    //~^ ERROR is not a supported ABI
+}
+
+impl S {
+    extern "amdgpu-kernel" fn imu() {} //~ ERROR amdgpu-kernel ABI is experimental
+    //~^ ERROR is not a supported ABI
+}
+
+type TAU = extern "amdgpu-kernel" fn(); //~ ERROR amdgpu-kernel ABI is experimental
+
+extern "amdgpu-kernel" {} //~ ERROR amdgpu-kernel ABI is experimental
+//~^ ERROR is not a supported ABI
diff --git a/tests/ui/feature-gates/feature-gate-abi_amdgpu_kernel.stderr b/tests/ui/feature-gates/feature-gate-abi_amdgpu_kernel.stderr
new file mode 100644
index 000000000..c89ab7bae
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi_amdgpu_kernel.stderr
@@ -0,0 +1,97 @@
+error[E0658]: amdgpu-kernel ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:7:8
+   |
+LL | extern "amdgpu-kernel" fn fu() {}
+   |        ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #51575 <https://github.com/rust-lang/rust/issues/51575> for more information
+   = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
+
+error[E0658]: amdgpu-kernel ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:11:12
+   |
+LL |     extern "amdgpu-kernel" fn mu();
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #51575 <https://github.com/rust-lang/rust/issues/51575> for more information
+   = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
+
+error[E0658]: amdgpu-kernel ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:12:12
+   |
+LL |     extern "amdgpu-kernel" fn dmu() {}
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #51575 <https://github.com/rust-lang/rust/issues/51575> for more information
+   = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
+
+error[E0658]: amdgpu-kernel ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:18:12
+   |
+LL |     extern "amdgpu-kernel" fn mu() {}
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #51575 <https://github.com/rust-lang/rust/issues/51575> for more information
+   = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
+
+error[E0658]: amdgpu-kernel ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:23:12
+   |
+LL |     extern "amdgpu-kernel" fn imu() {}
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #51575 <https://github.com/rust-lang/rust/issues/51575> for more information
+   = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
+
+error[E0658]: amdgpu-kernel ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:27:19
+   |
+LL | type TAU = extern "amdgpu-kernel" fn();
+   |                   ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #51575 <https://github.com/rust-lang/rust/issues/51575> for more information
+   = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
+
+error[E0658]: amdgpu-kernel ABI is experimental and subject to change
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:29:8
+   |
+LL | extern "amdgpu-kernel" {}
+   |        ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #51575 <https://github.com/rust-lang/rust/issues/51575> for more information
+   = help: add `#![feature(abi_amdgpu_kernel)]` to the crate attributes to enable
+
+error[E0570]: `"amdgpu-kernel"` is not a supported ABI for the current target
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:29:1
+   |
+LL | extern "amdgpu-kernel" {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0570]: `"amdgpu-kernel"` is not a supported ABI for the current target
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:7:1
+   |
+LL | extern "amdgpu-kernel" fn fu() {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0570]: `"amdgpu-kernel"` is not a supported ABI for the current target
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:12:5
+   |
+LL |     extern "amdgpu-kernel" fn dmu() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0570]: `"amdgpu-kernel"` is not a supported ABI for the current target
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:18:5
+   |
+LL |     extern "amdgpu-kernel" fn mu() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0570]: `"amdgpu-kernel"` is not a supported ABI for the current target
+  --> $DIR/feature-gate-abi_amdgpu_kernel.rs:23:5
+   |
+LL |     extern "amdgpu-kernel" fn imu() {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 12 previous errors
+
+Some errors have detailed explanations: E0570, E0658.
+For more information about an error, try `rustc --explain E0570`.
diff --git a/tests/ui/feature-gates/feature-gate-abi_ptx.rs b/tests/ui/feature-gates/feature-gate-abi_ptx.rs
new file mode 100644
index 000000000..e3405641e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi_ptx.rs
@@ -0,0 +1,26 @@
+// needs-llvm-components: nvptx
+// compile-flags: --target=nvptx64-nvidia-cuda --crate-type=rlib
+#![no_core]
+#![feature(no_core, lang_items)]
+#[lang="sized"]
+trait Sized { }
+
+extern "ptx-kernel" fn fu() {} //~ ERROR PTX ABIs are experimental
+
+trait T {
+    extern "ptx-kernel" fn mu(); //~ ERROR PTX ABIs are experimental
+    extern "ptx-kernel" fn dmu() {} //~ ERROR PTX ABIs are experimental
+}
+
+struct S;
+impl T for S {
+    extern "ptx-kernel" fn mu() {} //~ ERROR PTX ABIs are experimental
+}
+
+impl S {
+    extern "ptx-kernel" fn imu() {} //~ ERROR PTX ABIs are experimental
+}
+
+type TAU = extern "ptx-kernel" fn(); //~ ERROR PTX ABIs are experimental
+
+extern "ptx-kernel" {} //~ ERROR PTX ABIs are experimental
diff --git a/tests/ui/feature-gates/feature-gate-abi_ptx.stderr b/tests/ui/feature-gates/feature-gate-abi_ptx.stderr
new file mode 100644
index 000000000..40782d361
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi_ptx.stderr
@@ -0,0 +1,66 @@
+error[E0658]: PTX ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi_ptx.rs:8:8
+   |
+LL | extern "ptx-kernel" fn fu() {}
+   |        ^^^^^^^^^^^^
+   |
+   = note: see issue #38788 <https://github.com/rust-lang/rust/issues/38788> for more information
+   = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
+
+error[E0658]: PTX ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi_ptx.rs:11:12
+   |
+LL |     extern "ptx-kernel" fn mu();
+   |            ^^^^^^^^^^^^
+   |
+   = note: see issue #38788 <https://github.com/rust-lang/rust/issues/38788> for more information
+   = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
+
+error[E0658]: PTX ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi_ptx.rs:12:12
+   |
+LL |     extern "ptx-kernel" fn dmu() {}
+   |            ^^^^^^^^^^^^
+   |
+   = note: see issue #38788 <https://github.com/rust-lang/rust/issues/38788> for more information
+   = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
+
+error[E0658]: PTX ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi_ptx.rs:17:12
+   |
+LL |     extern "ptx-kernel" fn mu() {}
+   |            ^^^^^^^^^^^^
+   |
+   = note: see issue #38788 <https://github.com/rust-lang/rust/issues/38788> for more information
+   = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
+
+error[E0658]: PTX ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi_ptx.rs:21:12
+   |
+LL |     extern "ptx-kernel" fn imu() {}
+   |            ^^^^^^^^^^^^
+   |
+   = note: see issue #38788 <https://github.com/rust-lang/rust/issues/38788> for more information
+   = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
+
+error[E0658]: PTX ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi_ptx.rs:24:19
+   |
+LL | type TAU = extern "ptx-kernel" fn();
+   |                   ^^^^^^^^^^^^
+   |
+   = note: see issue #38788 <https://github.com/rust-lang/rust/issues/38788> for more information
+   = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
+
+error[E0658]: PTX ABIs are experimental and subject to change
+  --> $DIR/feature-gate-abi_ptx.rs:26:8
+   |
+LL | extern "ptx-kernel" {}
+   |        ^^^^^^^^^^^^
+   |
+   = note: see issue #38788 <https://github.com/rust-lang/rust/issues/38788> for more information
+   = help: add `#![feature(abi_ptx)]` to the crate attributes to enable
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-abi_unadjusted.rs b/tests/ui/feature-gates/feature-gate-abi_unadjusted.rs
new file mode 100644
index 000000000..35a7d7328
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi_unadjusted.rs
@@ -0,0 +1,7 @@
+extern "unadjusted" fn foo() {
+//~^ ERROR: unadjusted ABI is an implementation detail and perma-unstable
+}
+
+fn main() {
+    foo();
+}
diff --git a/tests/ui/feature-gates/feature-gate-abi_unadjusted.stderr b/tests/ui/feature-gates/feature-gate-abi_unadjusted.stderr
new file mode 100644
index 000000000..1757befec
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-abi_unadjusted.stderr
@@ -0,0 +1,11 @@
+error[E0658]: unadjusted ABI is an implementation detail and perma-unstable
+  --> $DIR/feature-gate-abi_unadjusted.rs:1:8
+   |
+LL | extern "unadjusted" fn foo() {
+   |        ^^^^^^^^^^^^
+   |
+   = help: add `#![feature(abi_unadjusted)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-adt_const_params.rs b/tests/ui/feature-gates/feature-gate-adt_const_params.rs
new file mode 100644
index 000000000..8a3bcf259
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-adt_const_params.rs
@@ -0,0 +1,2 @@
+struct Foo<const NAME: &'static str>; //~ ERROR `&'static str` is forbidden
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-adt_const_params.stderr b/tests/ui/feature-gates/feature-gate-adt_const_params.stderr
new file mode 100644
index 000000000..d8f089a28
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-adt_const_params.stderr
@@ -0,0 +1,11 @@
+error: `&'static str` is forbidden as the type of a const generic parameter
+  --> $DIR/feature-gate-adt_const_params.rs:1:24
+   |
+LL | struct Foo<const NAME: &'static str>;
+   |                        ^^^^^^^^^^^^
+   |
+   = note: the only supported types are integers, `bool` and `char`
+   = help: more complex types are supported with `#![feature(adt_const_params)]`
+
+error: aborting due to previous error
+
diff --git a/tests/ui/feature-gates/feature-gate-alloc-error-handler.rs b/tests/ui/feature-gates/feature-gate-alloc-error-handler.rs
new file mode 100644
index 000000000..78d189d20
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-alloc-error-handler.rs
@@ -0,0 +1,16 @@
+// compile-flags:-C panic=abort
+
+#![no_std]
+#![no_main]
+
+use core::alloc::Layout;
+
+#[alloc_error_handler] //~ ERROR use of unstable library feature 'alloc_error_handler'
+fn oom(info: Layout) -> ! {
+    loop {}
+}
+
+#[panic_handler]
+fn panic(_: &core::panic::PanicInfo) -> ! {
+    loop {}
+}
diff --git a/tests/ui/feature-gates/feature-gate-alloc-error-handler.stderr b/tests/ui/feature-gates/feature-gate-alloc-error-handler.stderr
new file mode 100644
index 000000000..f414eb463
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-alloc-error-handler.stderr
@@ -0,0 +1,12 @@
+error[E0658]: use of unstable library feature 'alloc_error_handler'
+  --> $DIR/feature-gate-alloc-error-handler.rs:8:3
+   |
+LL | #[alloc_error_handler]
+   |   ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #51540 <https://github.com/rust-lang/rust/issues/51540> for more information
+   = help: add `#![feature(alloc_error_handler)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-allocator_internals.rs b/tests/ui/feature-gates/feature-gate-allocator_internals.rs
new file mode 100644
index 000000000..a17d17da6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-allocator_internals.rs
@@ -0,0 +1,3 @@
+#![default_lib_allocator] //~ ERROR: attribute is an experimental feature
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-allocator_internals.stderr b/tests/ui/feature-gates/feature-gate-allocator_internals.stderr
new file mode 100644
index 000000000..6e276f7bc
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-allocator_internals.stderr
@@ -0,0 +1,11 @@
+error[E0658]: the `#[default_lib_allocator]` attribute is an experimental feature
+  --> $DIR/feature-gate-allocator_internals.rs:1:1
+   |
+LL | #![default_lib_allocator]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(allocator_internals)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-allow-internal-unsafe-nested-macro.rs b/tests/ui/feature-gates/feature-gate-allow-internal-unsafe-nested-macro.rs
new file mode 100644
index 000000000..9f604aafd
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-allow-internal-unsafe-nested-macro.rs
@@ -0,0 +1,17 @@
+// gate-test-allow_internal_unsafe
+
+#![allow(unused_macros)]
+
+macro_rules! bar {
+    () => {
+        // more layers don't help:
+        #[allow_internal_unsafe] //~ ERROR allow_internal_unsafe side-steps
+        macro_rules! baz {
+            () => {}
+        }
+    }
+}
+
+bar!();
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-allow-internal-unsafe-nested-macro.stderr b/tests/ui/feature-gates/feature-gate-allow-internal-unsafe-nested-macro.stderr
new file mode 100644
index 000000000..4621bc0b3
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-allow-internal-unsafe-nested-macro.stderr
@@ -0,0 +1,15 @@
+error[E0658]: allow_internal_unsafe side-steps the unsafe_code lint
+  --> $DIR/feature-gate-allow-internal-unsafe-nested-macro.rs:8:9
+   |
+LL |         #[allow_internal_unsafe]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | bar!();
+   | ------ in this macro invocation
+   |
+   = help: add `#![feature(allow_internal_unsafe)]` to the crate attributes to enable
+   = note: this error originates in the macro `bar` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-allow-internal-unstable-nested-macro.rs b/tests/ui/feature-gates/feature-gate-allow-internal-unstable-nested-macro.rs
new file mode 100644
index 000000000..ee48f9516
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-allow-internal-unstable-nested-macro.rs
@@ -0,0 +1,17 @@
+// gate-test-allow_internal_unstable
+
+#![allow(unused_macros)]
+
+macro_rules! bar {
+    () => {
+        // more layers don't help:
+        #[allow_internal_unstable()] //~ ERROR allow_internal_unstable side-steps
+        macro_rules! baz {
+            () => {}
+        }
+    }
+}
+
+bar!();
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-allow-internal-unstable-nested-macro.stderr b/tests/ui/feature-gates/feature-gate-allow-internal-unstable-nested-macro.stderr
new file mode 100644
index 000000000..1232d13a4
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-allow-internal-unstable-nested-macro.stderr
@@ -0,0 +1,15 @@
+error[E0658]: allow_internal_unstable side-steps feature gating and stability checks
+  --> $DIR/feature-gate-allow-internal-unstable-nested-macro.rs:8:9
+   |
+LL |         #[allow_internal_unstable()]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | bar!();
+   | ------ in this macro invocation
+   |
+   = help: add `#![feature(allow_internal_unstable)]` to the crate attributes to enable
+   = note: this error originates in the macro `bar` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-allow-internal-unstable-struct.rs b/tests/ui/feature-gates/feature-gate-allow-internal-unstable-struct.rs
new file mode 100644
index 000000000..8b13f1bf2
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-allow-internal-unstable-struct.rs
@@ -0,0 +1,8 @@
+// checks that this attribute is caught on non-macro items.
+// this needs a different test since this is done after expansion
+
+#[allow_internal_unstable()] //~ ERROR allow_internal_unstable side-steps
+//~| ERROR attribute should
+struct S;
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-allow-internal-unstable-struct.stderr b/tests/ui/feature-gates/feature-gate-allow-internal-unstable-struct.stderr
new file mode 100644
index 000000000..df7773ba4
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-allow-internal-unstable-struct.stderr
@@ -0,0 +1,20 @@
+error[E0658]: allow_internal_unstable side-steps feature gating and stability checks
+  --> $DIR/feature-gate-allow-internal-unstable-struct.rs:4:1
+   |
+LL | #[allow_internal_unstable()]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(allow_internal_unstable)]` to the crate attributes to enable
+
+error: attribute should be applied to a macro
+  --> $DIR/feature-gate-allow-internal-unstable-struct.rs:4:1
+   |
+LL | #[allow_internal_unstable()]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |
+LL | struct S;
+   | --------- not a macro
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-allow-internal-unstable.rs b/tests/ui/feature-gates/feature-gate-allow-internal-unstable.rs
new file mode 100644
index 000000000..0a1b6acd9
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-allow-internal-unstable.rs
@@ -0,0 +1,8 @@
+#![allow(unused_macros)]
+
+#[allow_internal_unstable()] //~ ERROR allow_internal_unstable side-steps
+macro_rules! foo {
+    () => {}
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-allow-internal-unstable.stderr b/tests/ui/feature-gates/feature-gate-allow-internal-unstable.stderr
new file mode 100644
index 000000000..3c1a4bfc7
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-allow-internal-unstable.stderr
@@ -0,0 +1,11 @@
+error[E0658]: allow_internal_unstable side-steps feature gating and stability checks
+  --> $DIR/feature-gate-allow-internal-unstable.rs:3:1
+   |
+LL | #[allow_internal_unstable()]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(allow_internal_unstable)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-arbitrary-self-types.rs b/tests/ui/feature-gates/feature-gate-arbitrary-self-types.rs
new file mode 100644
index 000000000..47ca7e349
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-arbitrary-self-types.rs
@@ -0,0 +1,29 @@
+use std::{
+    ops::Deref,
+};
+
+struct Ptr<T: ?Sized>(Box<T>);
+
+impl<T: ?Sized> Deref for Ptr<T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        &*self.0
+    }
+}
+
+trait Foo {
+    fn foo(self: Ptr<Self>); //~ ERROR `Ptr<Self>` cannot be used as the type of `self` without
+}
+
+struct Bar;
+
+impl Foo for Bar {
+    fn foo(self: Ptr<Self>) {} //~ ERROR `Ptr<Bar>` cannot be used as the type of `self` without
+}
+
+impl Bar {
+    fn bar(self: Box<Ptr<Self>>) {} //~ ERROR `Box<Ptr<Bar>>` cannot be used as the
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-arbitrary-self-types.stderr b/tests/ui/feature-gates/feature-gate-arbitrary-self-types.stderr
new file mode 100644
index 000000000..a1c69a5af
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-arbitrary-self-types.stderr
@@ -0,0 +1,33 @@
+error[E0658]: `Ptr<Bar>` cannot be used as the type of `self` without the `arbitrary_self_types` feature
+  --> $DIR/feature-gate-arbitrary-self-types.rs:22:18
+   |
+LL |     fn foo(self: Ptr<Self>) {}
+   |                  ^^^^^^^^^
+   |
+   = note: see issue #44874 <https://github.com/rust-lang/rust/issues/44874> for more information
+   = help: add `#![feature(arbitrary_self_types)]` to the crate attributes to enable
+   = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
+
+error[E0658]: `Box<Ptr<Bar>>` cannot be used as the type of `self` without the `arbitrary_self_types` feature
+  --> $DIR/feature-gate-arbitrary-self-types.rs:26:18
+   |
+LL |     fn bar(self: Box<Ptr<Self>>) {}
+   |                  ^^^^^^^^^^^^^^
+   |
+   = note: see issue #44874 <https://github.com/rust-lang/rust/issues/44874> for more information
+   = help: add `#![feature(arbitrary_self_types)]` to the crate attributes to enable
+   = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
+
+error[E0658]: `Ptr<Self>` cannot be used as the type of `self` without the `arbitrary_self_types` feature
+  --> $DIR/feature-gate-arbitrary-self-types.rs:16:18
+   |
+LL |     fn foo(self: Ptr<Self>);
+   |                  ^^^^^^^^^
+   |
+   = note: see issue #44874 <https://github.com/rust-lang/rust/issues/44874> for more information
+   = help: add `#![feature(arbitrary_self_types)]` to the crate attributes to enable
+   = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-arbitrary_self_types-raw-pointer.rs b/tests/ui/feature-gates/feature-gate-arbitrary_self_types-raw-pointer.rs
new file mode 100644
index 000000000..f7e94117e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-arbitrary_self_types-raw-pointer.rs
@@ -0,0 +1,18 @@
+struct Foo;
+
+impl Foo {
+    fn foo(self: *const Self) {}
+    //~^ ERROR `*const Foo` cannot be used as the type of `self` without
+}
+
+trait Bar {
+    fn bar(self: *const Self);
+    //~^ ERROR `*const Self` cannot be used as the type of `self` without
+}
+
+impl Bar for () {
+    fn bar(self: *const Self) {}
+    //~^ ERROR `*const ()` cannot be used as the type of `self` without
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-arbitrary_self_types-raw-pointer.stderr b/tests/ui/feature-gates/feature-gate-arbitrary_self_types-raw-pointer.stderr
new file mode 100644
index 000000000..a9f611b87
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-arbitrary_self_types-raw-pointer.stderr
@@ -0,0 +1,33 @@
+error[E0658]: `*const Foo` cannot be used as the type of `self` without the `arbitrary_self_types` feature
+  --> $DIR/feature-gate-arbitrary_self_types-raw-pointer.rs:4:18
+   |
+LL |     fn foo(self: *const Self) {}
+   |                  ^^^^^^^^^^^
+   |
+   = note: see issue #44874 <https://github.com/rust-lang/rust/issues/44874> for more information
+   = help: add `#![feature(arbitrary_self_types)]` to the crate attributes to enable
+   = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
+
+error[E0658]: `*const ()` cannot be used as the type of `self` without the `arbitrary_self_types` feature
+  --> $DIR/feature-gate-arbitrary_self_types-raw-pointer.rs:14:18
+   |
+LL |     fn bar(self: *const Self) {}
+   |                  ^^^^^^^^^^^
+   |
+   = note: see issue #44874 <https://github.com/rust-lang/rust/issues/44874> for more information
+   = help: add `#![feature(arbitrary_self_types)]` to the crate attributes to enable
+   = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
+
+error[E0658]: `*const Self` cannot be used as the type of `self` without the `arbitrary_self_types` feature
+  --> $DIR/feature-gate-arbitrary_self_types-raw-pointer.rs:9:18
+   |
+LL |     fn bar(self: *const Self);
+   |                  ^^^^^^^^^^^
+   |
+   = note: see issue #44874 <https://github.com/rust-lang/rust/issues/44874> for more information
+   = help: add `#![feature(arbitrary_self_types)]` to the crate attributes to enable
+   = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-asm_const.rs b/tests/ui/feature-gates/feature-gate-asm_const.rs
new file mode 100644
index 000000000..936918a3c
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-asm_const.rs
@@ -0,0 +1,16 @@
+// only-x86_64
+
+use std::arch::asm;
+
+unsafe fn foo<const N: usize>() {
+    asm!("mov eax, {}", const N + 1);
+    //~^ ERROR const operands for inline assembly are unstable
+}
+
+fn main() {
+    unsafe {
+        foo::<0>();
+        asm!("mov eax, {}", const 123);
+        //~^ ERROR const operands for inline assembly are unstable
+    }
+}
diff --git a/tests/ui/feature-gates/feature-gate-asm_const.stderr b/tests/ui/feature-gates/feature-gate-asm_const.stderr
new file mode 100644
index 000000000..c248374ec
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-asm_const.stderr
@@ -0,0 +1,21 @@
+error[E0658]: const operands for inline assembly are unstable
+  --> $DIR/feature-gate-asm_const.rs:6:25
+   |
+LL |     asm!("mov eax, {}", const N + 1);
+   |                         ^^^^^^^^^^^
+   |
+   = note: see issue #93332 <https://github.com/rust-lang/rust/issues/93332> for more information
+   = help: add `#![feature(asm_const)]` to the crate attributes to enable
+
+error[E0658]: const operands for inline assembly are unstable
+  --> $DIR/feature-gate-asm_const.rs:13:29
+   |
+LL |         asm!("mov eax, {}", const 123);
+   |                             ^^^^^^^^^
+   |
+   = note: see issue #93332 <https://github.com/rust-lang/rust/issues/93332> for more information
+   = help: add `#![feature(asm_const)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-asm_experimental_arch.rs b/tests/ui/feature-gates/feature-gate-asm_experimental_arch.rs
new file mode 100644
index 000000000..53e2a4d13
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-asm_experimental_arch.rs
@@ -0,0 +1,21 @@
+// compile-flags: --target mips-unknown-linux-gnu
+// needs-llvm-components: mips
+
+#![feature(no_core, lang_items, rustc_attrs)]
+#![crate_type = "rlib"]
+#![no_core]
+
+#[rustc_builtin_macro]
+macro_rules! asm {
+    () => {};
+}
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+unsafe fn main() {
+    asm!("");
+    //~^ ERROR inline assembly is not stable yet on this architecture
+}
diff --git a/tests/ui/feature-gates/feature-gate-asm_experimental_arch.stderr b/tests/ui/feature-gates/feature-gate-asm_experimental_arch.stderr
new file mode 100644
index 000000000..4a859430e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-asm_experimental_arch.stderr
@@ -0,0 +1,12 @@
+error[E0658]: inline assembly is not stable yet on this architecture
+  --> $DIR/feature-gate-asm_experimental_arch.rs:19:5
+   |
+LL |     asm!("");
+   |     ^^^^^^^^
+   |
+   = note: see issue #93335 <https://github.com/rust-lang/rust/issues/93335> for more information
+   = help: add `#![feature(asm_experimental_arch)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-asm_unwind.rs b/tests/ui/feature-gates/feature-gate-asm_unwind.rs
new file mode 100644
index 000000000..df161b600
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-asm_unwind.rs
@@ -0,0 +1,10 @@
+// only-x86_64
+
+use std::arch::asm;
+
+fn main() {
+    unsafe {
+        asm!("", options(may_unwind));
+        //~^ ERROR the `may_unwind` option is unstable
+    }
+}
diff --git a/tests/ui/feature-gates/feature-gate-asm_unwind.stderr b/tests/ui/feature-gates/feature-gate-asm_unwind.stderr
new file mode 100644
index 000000000..05e66acb5
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-asm_unwind.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `may_unwind` option is unstable
+  --> $DIR/feature-gate-asm_unwind.rs:7:9
+   |
+LL |         asm!("", options(may_unwind));
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #93334 <https://github.com/rust-lang/rust/issues/93334> for more information
+   = help: add `#![feature(asm_unwind)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-assoc-type-defaults.rs b/tests/ui/feature-gates/feature-gate-assoc-type-defaults.rs
new file mode 100644
index 000000000..d7c6a9f97
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-assoc-type-defaults.rs
@@ -0,0 +1,7 @@
+// gate-test-associated_type_defaults
+
+trait Foo {
+    type Bar = u8; //~ ERROR associated type defaults are unstable
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-assoc-type-defaults.stderr b/tests/ui/feature-gates/feature-gate-assoc-type-defaults.stderr
new file mode 100644
index 000000000..9edad6153
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-assoc-type-defaults.stderr
@@ -0,0 +1,12 @@
+error[E0658]: associated type defaults are unstable
+  --> $DIR/feature-gate-assoc-type-defaults.rs:4:5
+   |
+LL |     type Bar = u8;
+   |     ^^^^^^^^^^^^^^
+   |
+   = note: see issue #29661 <https://github.com/rust-lang/rust/issues/29661> for more information
+   = help: add `#![feature(associated_type_defaults)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-associated_const_equality.rs b/tests/ui/feature-gates/feature-gate-associated_const_equality.rs
new file mode 100644
index 000000000..2534c527b
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-associated_const_equality.rs
@@ -0,0 +1,15 @@
+pub trait TraitWAssocConst {
+  const A: usize;
+}
+pub struct Demo {}
+
+impl TraitWAssocConst for Demo {
+  const A: usize = 32;
+}
+
+fn foo<A: TraitWAssocConst<A=32>>() {}
+//~^ ERROR associated const equality
+
+fn main() {
+  foo::<Demo>();
+}
diff --git a/tests/ui/feature-gates/feature-gate-associated_const_equality.stderr b/tests/ui/feature-gates/feature-gate-associated_const_equality.stderr
new file mode 100644
index 000000000..6563fbcba
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-associated_const_equality.stderr
@@ -0,0 +1,12 @@
+error[E0658]: associated const equality is incomplete
+  --> $DIR/feature-gate-associated_const_equality.rs:10:28
+   |
+LL | fn foo<A: TraitWAssocConst<A=32>>() {}
+   |                            ^^^^
+   |
+   = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
+   = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-associated_type_bounds.rs b/tests/ui/feature-gates/feature-gate-associated_type_bounds.rs
new file mode 100644
index 000000000..4e0203274
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-associated_type_bounds.rs
@@ -0,0 +1,76 @@
+// compile-flags: -Zsave-analysis
+// This is also a regression test for #69415 and the above flag is needed.
+
+use std::mem::ManuallyDrop;
+
+trait Tr1 { type As1: Copy; }
+trait Tr2 { type As2: Copy; }
+
+struct S1;
+#[derive(Copy, Clone)]
+struct S2;
+impl Tr1 for S1 { type As1 = S2; }
+
+trait _Tr3 {
+    type A: Iterator<Item: Copy>;
+    //~^ ERROR associated type bounds are unstable
+    //~| ERROR the trait bound `<<Self as _Tr3>::A as Iterator>::Item: Copy` is not satisfied
+
+    type B: Iterator<Item: 'static>;
+    //~^ ERROR associated type bounds are unstable
+}
+
+struct _St1<T: Tr1<As1: Tr2>> {
+//~^ ERROR associated type bounds are unstable
+    outest: T,
+    outer: T::As1,
+    inner: <T::As1 as Tr2>::As2,
+}
+
+enum _En1<T: Tr1<As1: Tr2>> {
+//~^ ERROR associated type bounds are unstable
+    Outest(T),
+    Outer(T::As1),
+    Inner(<T::As1 as Tr2>::As2),
+}
+
+union _Un1<T: Tr1<As1: Tr2>> {
+//~^ ERROR associated type bounds are unstable
+    outest: ManuallyDrop<T>,
+    outer: ManuallyDrop<T::As1>,
+    inner: ManuallyDrop<<T::As1 as Tr2>::As2>,
+}
+
+type _TaWhere1<T> where T: Iterator<Item: Copy> = T;
+//~^ ERROR associated type bounds are unstable
+
+fn _apit(_: impl Tr1<As1: Copy>) {}
+//~^ ERROR associated type bounds are unstable
+fn _apit_dyn(_: &dyn Tr1<As1: Copy>) {}
+//~^ ERROR associated type bounds are unstable
+
+fn _rpit() -> impl Tr1<As1: Copy> { S1 }
+//~^ ERROR associated type bounds are unstable
+
+fn _rpit_dyn() -> Box<dyn Tr1<As1: Copy>> { Box::new(S1) }
+//~^ ERROR associated type bounds are unstable
+
+const _cdef: impl Tr1<As1: Copy> = S1;
+//~^ ERROR associated type bounds are unstable
+//~| ERROR `impl Trait` only allowed in function and inherent method return types
+// FIXME: uncomment when `impl_trait_in_bindings` feature is fixed.
+// const _cdef_dyn: &dyn Tr1<As1: Copy> = &S1;
+
+static _sdef: impl Tr1<As1: Copy> = S1;
+//~^ ERROR associated type bounds are unstable
+//~| ERROR `impl Trait` only allowed in function and inherent method return types
+// FIXME: uncomment when `impl_trait_in_bindings` feature is fixed.
+// static _sdef_dyn: &dyn Tr1<As1: Copy> = &S1;
+
+fn main() {
+    let _: impl Tr1<As1: Copy> = S1;
+    //~^ ERROR associated type bounds are unstable
+    //~| ERROR `impl Trait` only allowed in function and inherent method return types
+    // FIXME: uncomment when `impl_trait_in_bindings` feature is fixed.
+    // let _: &dyn Tr1<As1: Copy> = &S1;
+}
diff --git a/tests/ui/feature-gates/feature-gate-associated_type_bounds.stderr b/tests/ui/feature-gates/feature-gate-associated_type_bounds.stderr
new file mode 100644
index 000000000..5be1d97a0
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-associated_type_bounds.stderr
@@ -0,0 +1,150 @@
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:15:22
+   |
+LL |     type A: Iterator<Item: Copy>;
+   |                      ^^^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:19:22
+   |
+LL |     type B: Iterator<Item: 'static>;
+   |                      ^^^^^^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:23:20
+   |
+LL | struct _St1<T: Tr1<As1: Tr2>> {
+   |                    ^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:30:18
+   |
+LL | enum _En1<T: Tr1<As1: Tr2>> {
+   |                  ^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:37:19
+   |
+LL | union _Un1<T: Tr1<As1: Tr2>> {
+   |                   ^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:44:37
+   |
+LL | type _TaWhere1<T> where T: Iterator<Item: Copy> = T;
+   |                                     ^^^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:47:22
+   |
+LL | fn _apit(_: impl Tr1<As1: Copy>) {}
+   |                      ^^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:49:26
+   |
+LL | fn _apit_dyn(_: &dyn Tr1<As1: Copy>) {}
+   |                          ^^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:52:24
+   |
+LL | fn _rpit() -> impl Tr1<As1: Copy> { S1 }
+   |                        ^^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:55:31
+   |
+LL | fn _rpit_dyn() -> Box<dyn Tr1<As1: Copy>> { Box::new(S1) }
+   |                               ^^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:58:23
+   |
+LL | const _cdef: impl Tr1<As1: Copy> = S1;
+   |                       ^^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:64:24
+   |
+LL | static _sdef: impl Tr1<As1: Copy> = S1;
+   |                        ^^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0658]: associated type bounds are unstable
+  --> $DIR/feature-gate-associated_type_bounds.rs:71:21
+   |
+LL |     let _: impl Tr1<As1: Copy> = S1;
+   |                     ^^^^^^^^^
+   |
+   = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
+   = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
+
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in type
+  --> $DIR/feature-gate-associated_type_bounds.rs:58:14
+   |
+LL | const _cdef: impl Tr1<As1: Copy> = S1;
+   |              ^^^^^^^^^^^^^^^^^^^
+
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in type
+  --> $DIR/feature-gate-associated_type_bounds.rs:64:15
+   |
+LL | static _sdef: impl Tr1<As1: Copy> = S1;
+   |               ^^^^^^^^^^^^^^^^^^^
+
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+  --> $DIR/feature-gate-associated_type_bounds.rs:71:12
+   |
+LL |     let _: impl Tr1<As1: Copy> = S1;
+   |            ^^^^^^^^^^^^^^^^^^^
+
+error[E0277]: the trait bound `<<Self as _Tr3>::A as Iterator>::Item: Copy` is not satisfied
+  --> $DIR/feature-gate-associated_type_bounds.rs:15:28
+   |
+LL |     type A: Iterator<Item: Copy>;
+   |                            ^^^^ the trait `Copy` is not implemented for `<<Self as _Tr3>::A as Iterator>::Item`
+   |
+help: consider further restricting the associated type
+   |
+LL | trait _Tr3 where <<Self as _Tr3>::A as Iterator>::Item: Copy {
+   |            +++++++++++++++++++++++++++++++++++++++++++++++++
+
+error: aborting due to 17 previous errors
+
+Some errors have detailed explanations: E0277, E0562, E0658.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/feature-gates/feature-gate-auto-traits.rs b/tests/ui/feature-gates/feature-gate-auto-traits.rs
new file mode 100644
index 000000000..80cfa9cee
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-auto-traits.rs
@@ -0,0 +1,12 @@
+// Test that default and negative trait implementations are gated by
+// `auto_traits` feature gate
+
+struct DummyStruct;
+
+auto trait AutoDummyTrait {}
+//~^ ERROR auto traits are experimental and possibly buggy
+
+impl !AutoDummyTrait for DummyStruct {}
+//~^ ERROR negative trait bounds are not yet fully implemented; use marker types for now
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-auto-traits.stderr b/tests/ui/feature-gates/feature-gate-auto-traits.stderr
new file mode 100644
index 000000000..e01541816
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-auto-traits.stderr
@@ -0,0 +1,21 @@
+error[E0658]: auto traits are experimental and possibly buggy
+  --> $DIR/feature-gate-auto-traits.rs:6:1
+   |
+LL | auto trait AutoDummyTrait {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #13231 <https://github.com/rust-lang/rust/issues/13231> for more information
+   = help: add `#![feature(auto_traits)]` to the crate attributes to enable
+
+error[E0658]: negative trait bounds are not yet fully implemented; use marker types for now
+  --> $DIR/feature-gate-auto-traits.rs:9:6
+   |
+LL | impl !AutoDummyTrait for DummyStruct {}
+   |      ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #68318 <https://github.com/rust-lang/rust/issues/68318> for more information
+   = help: add `#![feature(negative_impls)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-box-expr.rs b/tests/ui/feature-gates/feature-gate-box-expr.rs
new file mode 100644
index 000000000..870253d2f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-box-expr.rs
@@ -0,0 +1,14 @@
+// gate-test-box_syntax
+
+// Check that `box EXPR` is feature-gated.
+//
+// See also feature-gate-placement-expr.rs
+//
+// (Note that the two tests are separated since the checks appear to
+// be performed at distinct phases, with an abort_if_errors call
+// separating them.)
+
+fn main() {
+    let x = box 'c'; //~ ERROR box expression syntax is experimental
+    println!("x: {}", x);
+}
diff --git a/tests/ui/feature-gates/feature-gate-box-expr.stderr b/tests/ui/feature-gates/feature-gate-box-expr.stderr
new file mode 100644
index 000000000..af864b25f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-box-expr.stderr
@@ -0,0 +1,12 @@
+error[E0658]: box expression syntax is experimental; you can call `Box::new` instead
+  --> $DIR/feature-gate-box-expr.rs:12:13
+   |
+LL |     let x = box 'c';
+   |             ^^^^^^^
+   |
+   = note: see issue #49733 <https://github.com/rust-lang/rust/issues/49733> for more information
+   = help: add `#![feature(box_syntax)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-box_patterns.rs b/tests/ui/feature-gates/feature-gate-box_patterns.rs
new file mode 100644
index 000000000..8bec16a97
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-box_patterns.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let box x = Box::new('c'); //~ ERROR box pattern syntax is experimental
+    println!("x: {}", x);
+}
diff --git a/tests/ui/feature-gates/feature-gate-box_patterns.stderr b/tests/ui/feature-gates/feature-gate-box_patterns.stderr
new file mode 100644
index 000000000..601ec46a4
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-box_patterns.stderr
@@ -0,0 +1,12 @@
+error[E0658]: box pattern syntax is experimental
+  --> $DIR/feature-gate-box_patterns.rs:2:9
+   |
+LL |     let box x = Box::new('c');
+   |         ^^^^^
+   |
+   = note: see issue #29641 <https://github.com/rust-lang/rust/issues/29641> for more information
+   = help: add `#![feature(box_patterns)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-box_syntax.rs b/tests/ui/feature-gates/feature-gate-box_syntax.rs
new file mode 100644
index 000000000..778660cc0
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-box_syntax.rs
@@ -0,0 +1,6 @@
+// Test that the use of the box syntax is gated by `box_syntax` feature gate.
+
+fn main() {
+    let x = box 3;
+    //~^ ERROR box expression syntax is experimental; you can call `Box::new` instead
+}
diff --git a/tests/ui/feature-gates/feature-gate-box_syntax.stderr b/tests/ui/feature-gates/feature-gate-box_syntax.stderr
new file mode 100644
index 000000000..dcf8eeed7
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-box_syntax.stderr
@@ -0,0 +1,12 @@
+error[E0658]: box expression syntax is experimental; you can call `Box::new` instead
+  --> $DIR/feature-gate-box_syntax.rs:4:13
+   |
+LL |     let x = box 3;
+   |             ^^^^^
+   |
+   = note: see issue #49733 <https://github.com/rust-lang/rust/issues/49733> for more information
+   = help: add `#![feature(box_syntax)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-c_variadic.rs b/tests/ui/feature-gates/feature-gate-c_variadic.rs
new file mode 100644
index 000000000..8b40c36c7
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-c_variadic.rs
@@ -0,0 +1,4 @@
+#![crate_type="lib"]
+
+pub unsafe extern "C" fn test(_: i32, ap: ...) { }
+//~^ C-variadic functions are unstable
diff --git a/tests/ui/feature-gates/feature-gate-c_variadic.stderr b/tests/ui/feature-gates/feature-gate-c_variadic.stderr
new file mode 100644
index 000000000..7b3af8d99
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-c_variadic.stderr
@@ -0,0 +1,12 @@
+error[E0658]: C-variadic functions are unstable
+  --> $DIR/feature-gate-c_variadic.rs:3:1
+   |
+LL | pub unsafe extern "C" fn test(_: i32, ap: ...) { }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #44930 <https://github.com/rust-lang/rust/issues/44930> for more information
+   = help: add `#![feature(c_variadic)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-cfg-target-abi.rs b/tests/ui/feature-gates/feature-gate-cfg-target-abi.rs
new file mode 100644
index 000000000..d005dc3ad
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-target-abi.rs
@@ -0,0 +1,13 @@
+#[cfg(target_abi = "x")] //~ ERROR `cfg(target_abi)` is experimental
+struct Foo(u64, u64);
+
+#[cfg_attr(target_abi = "x", x)] //~ ERROR `cfg(target_abi)` is experimental
+struct Bar(u64, u64);
+
+#[cfg(not(any(all(target_abi = "x"))))] //~ ERROR `cfg(target_abi)` is experimental
+fn foo() {}
+
+fn main() {
+    cfg!(target_abi = "x");
+    //~^ ERROR `cfg(target_abi)` is experimental and subject to change
+}
diff --git a/tests/ui/feature-gates/feature-gate-cfg-target-abi.stderr b/tests/ui/feature-gates/feature-gate-cfg-target-abi.stderr
new file mode 100644
index 000000000..013705d48
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-target-abi.stderr
@@ -0,0 +1,39 @@
+error[E0658]: `cfg(target_abi)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-abi.rs:1:7
+   |
+LL | #[cfg(target_abi = "x")]
+   |       ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #80970 <https://github.com/rust-lang/rust/issues/80970> for more information
+   = help: add `#![feature(cfg_target_abi)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_abi)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-abi.rs:4:12
+   |
+LL | #[cfg_attr(target_abi = "x", x)]
+   |            ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #80970 <https://github.com/rust-lang/rust/issues/80970> for more information
+   = help: add `#![feature(cfg_target_abi)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_abi)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-abi.rs:7:19
+   |
+LL | #[cfg(not(any(all(target_abi = "x"))))]
+   |                   ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #80970 <https://github.com/rust-lang/rust/issues/80970> for more information
+   = help: add `#![feature(cfg_target_abi)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_abi)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-abi.rs:11:10
+   |
+LL |     cfg!(target_abi = "x");
+   |          ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #80970 <https://github.com/rust-lang/rust/issues/80970> for more information
+   = help: add `#![feature(cfg_target_abi)]` to the crate attributes to enable
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-cfg-target-compact.rs b/tests/ui/feature-gates/feature-gate-cfg-target-compact.rs
new file mode 100644
index 000000000..df81b7d22
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-target-compact.rs
@@ -0,0 +1,13 @@
+#[cfg(target(os = "x"))] //~ ERROR compact `cfg(target(..))` is experimental
+struct Foo(u64, u64);
+
+#[cfg_attr(target(os = "x"), x)] //~ ERROR compact `cfg(target(..))` is experimental
+struct Bar(u64, u64);
+
+#[cfg(not(any(all(target(os = "x")))))] //~ ERROR compact `cfg(target(..))` is experimental
+fn foo() {}
+
+fn main() {
+    cfg!(target(os = "x"));
+    //~^ ERROR compact `cfg(target(..))` is experimental and subject to change
+}
diff --git a/tests/ui/feature-gates/feature-gate-cfg-target-compact.stderr b/tests/ui/feature-gates/feature-gate-cfg-target-compact.stderr
new file mode 100644
index 000000000..be6fe23de
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-target-compact.stderr
@@ -0,0 +1,39 @@
+error[E0658]: compact `cfg(target(..))` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-compact.rs:1:7
+   |
+LL | #[cfg(target(os = "x"))]
+   |       ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #96901 <https://github.com/rust-lang/rust/issues/96901> for more information
+   = help: add `#![feature(cfg_target_compact)]` to the crate attributes to enable
+
+error[E0658]: compact `cfg(target(..))` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-compact.rs:4:12
+   |
+LL | #[cfg_attr(target(os = "x"), x)]
+   |            ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #96901 <https://github.com/rust-lang/rust/issues/96901> for more information
+   = help: add `#![feature(cfg_target_compact)]` to the crate attributes to enable
+
+error[E0658]: compact `cfg(target(..))` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-compact.rs:7:19
+   |
+LL | #[cfg(not(any(all(target(os = "x")))))]
+   |                   ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #96901 <https://github.com/rust-lang/rust/issues/96901> for more information
+   = help: add `#![feature(cfg_target_compact)]` to the crate attributes to enable
+
+error[E0658]: compact `cfg(target(..))` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-compact.rs:11:10
+   |
+LL |     cfg!(target(os = "x"));
+   |          ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #96901 <https://github.com/rust-lang/rust/issues/96901> for more information
+   = help: add `#![feature(cfg_target_compact)]` to the crate attributes to enable
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic-equal-alignment.rs b/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic-equal-alignment.rs
new file mode 100644
index 000000000..3d692a070
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic-equal-alignment.rs
@@ -0,0 +1,14 @@
+fn main() {
+    cfg!(target_has_atomic_equal_alignment = "8");
+    //~^ ERROR `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+    cfg!(target_has_atomic_equal_alignment = "16");
+    //~^ ERROR `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+    cfg!(target_has_atomic_equal_alignment = "32");
+    //~^ ERROR `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+    cfg!(target_has_atomic_equal_alignment = "64");
+    //~^ ERROR `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+    cfg!(target_has_atomic_equal_alignment = "128");
+    //~^ ERROR `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+    cfg!(target_has_atomic_equal_alignment = "ptr");
+    //~^ ERROR `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+}
diff --git a/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic-equal-alignment.stderr b/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic-equal-alignment.stderr
new file mode 100644
index 000000000..8ad3b034a
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic-equal-alignment.stderr
@@ -0,0 +1,57 @@
+error[E0658]: `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic-equal-alignment.rs:2:10
+   |
+LL |     cfg!(target_has_atomic_equal_alignment = "8");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #93822 <https://github.com/rust-lang/rust/issues/93822> for more information
+   = help: add `#![feature(cfg_target_has_atomic_equal_alignment)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic-equal-alignment.rs:4:10
+   |
+LL |     cfg!(target_has_atomic_equal_alignment = "16");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #93822 <https://github.com/rust-lang/rust/issues/93822> for more information
+   = help: add `#![feature(cfg_target_has_atomic_equal_alignment)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic-equal-alignment.rs:6:10
+   |
+LL |     cfg!(target_has_atomic_equal_alignment = "32");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #93822 <https://github.com/rust-lang/rust/issues/93822> for more information
+   = help: add `#![feature(cfg_target_has_atomic_equal_alignment)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic-equal-alignment.rs:8:10
+   |
+LL |     cfg!(target_has_atomic_equal_alignment = "64");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #93822 <https://github.com/rust-lang/rust/issues/93822> for more information
+   = help: add `#![feature(cfg_target_has_atomic_equal_alignment)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic-equal-alignment.rs:10:10
+   |
+LL |     cfg!(target_has_atomic_equal_alignment = "128");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #93822 <https://github.com/rust-lang/rust/issues/93822> for more information
+   = help: add `#![feature(cfg_target_has_atomic_equal_alignment)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_has_atomic_equal_alignment)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic-equal-alignment.rs:12:10
+   |
+LL |     cfg!(target_has_atomic_equal_alignment = "ptr");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #93822 <https://github.com/rust-lang/rust/issues/93822> for more information
+   = help: add `#![feature(cfg_target_has_atomic_equal_alignment)]` to the crate attributes to enable
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic.rs b/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic.rs
new file mode 100644
index 000000000..df9c51cb1
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic.rs
@@ -0,0 +1,14 @@
+fn main() {
+    cfg!(target_has_atomic_load_store = "8");
+    //~^ ERROR `cfg(target_has_atomic_load_store)` is experimental and subject to change
+    cfg!(target_has_atomic_load_store = "16");
+    //~^ ERROR `cfg(target_has_atomic_load_store)` is experimental and subject to change
+    cfg!(target_has_atomic_load_store = "32");
+    //~^ ERROR `cfg(target_has_atomic_load_store)` is experimental and subject to change
+    cfg!(target_has_atomic_load_store = "64");
+    //~^ ERROR `cfg(target_has_atomic_load_store)` is experimental and subject to change
+    cfg!(target_has_atomic_load_store = "128");
+    //~^ ERROR `cfg(target_has_atomic_load_store)` is experimental and subject to change
+    cfg!(target_has_atomic_load_store = "ptr");
+    //~^ ERROR `cfg(target_has_atomic_load_store)` is experimental and subject to change
+}
diff --git a/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic.stderr b/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic.stderr
new file mode 100644
index 000000000..b9e6830a9
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-target-has-atomic.stderr
@@ -0,0 +1,57 @@
+error[E0658]: `cfg(target_has_atomic_load_store)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic.rs:2:10
+   |
+LL |     cfg!(target_has_atomic_load_store = "8");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #94039 <https://github.com/rust-lang/rust/issues/94039> for more information
+   = help: add `#![feature(cfg_target_has_atomic)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_has_atomic_load_store)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic.rs:4:10
+   |
+LL |     cfg!(target_has_atomic_load_store = "16");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #94039 <https://github.com/rust-lang/rust/issues/94039> for more information
+   = help: add `#![feature(cfg_target_has_atomic)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_has_atomic_load_store)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic.rs:6:10
+   |
+LL |     cfg!(target_has_atomic_load_store = "32");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #94039 <https://github.com/rust-lang/rust/issues/94039> for more information
+   = help: add `#![feature(cfg_target_has_atomic)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_has_atomic_load_store)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic.rs:8:10
+   |
+LL |     cfg!(target_has_atomic_load_store = "64");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #94039 <https://github.com/rust-lang/rust/issues/94039> for more information
+   = help: add `#![feature(cfg_target_has_atomic)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_has_atomic_load_store)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic.rs:10:10
+   |
+LL |     cfg!(target_has_atomic_load_store = "128");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #94039 <https://github.com/rust-lang/rust/issues/94039> for more information
+   = help: add `#![feature(cfg_target_has_atomic)]` to the crate attributes to enable
+
+error[E0658]: `cfg(target_has_atomic_load_store)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-has-atomic.rs:12:10
+   |
+LL |     cfg!(target_has_atomic_load_store = "ptr");
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #94039 <https://github.com/rust-lang/rust/issues/94039> for more information
+   = help: add `#![feature(cfg_target_has_atomic)]` to the crate attributes to enable
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-cfg-target-thread-local.rs b/tests/ui/feature-gates/feature-gate-cfg-target-thread-local.rs
new file mode 100644
index 000000000..b600ad23e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-target-thread-local.rs
@@ -0,0 +1,16 @@
+// ignore-windows
+// aux-build:cfg-target-thread-local.rs
+
+#![feature(thread_local)]
+
+extern crate cfg_target_thread_local;
+
+extern "C" {
+    #[cfg_attr(target_thread_local, thread_local)]
+    //~^ `cfg(target_thread_local)` is experimental and subject to change
+    static FOO: u32;
+}
+
+fn main() {
+    assert_eq!(FOO, 3);
+}
diff --git a/tests/ui/feature-gates/feature-gate-cfg-target-thread-local.stderr b/tests/ui/feature-gates/feature-gate-cfg-target-thread-local.stderr
new file mode 100644
index 000000000..af59c7141
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-target-thread-local.stderr
@@ -0,0 +1,12 @@
+error[E0658]: `cfg(target_thread_local)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-target-thread-local.rs:9:16
+   |
+LL |     #[cfg_attr(target_thread_local, thread_local)]
+   |                ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #29594 <https://github.com/rust-lang/rust/issues/29594> for more information
+   = help: add `#![feature(cfg_target_thread_local)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-cfg-version.rs b/tests/ui/feature-gates/feature-gate-cfg-version.rs
new file mode 100644
index 000000000..e35784a68
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-version.rs
@@ -0,0 +1,49 @@
+#[cfg(version(42))] //~ ERROR: expected a version literal
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn foo() {}
+#[cfg(version(1.20))] //~ ERROR: expected a version literal
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn foo() -> bool { true }
+#[cfg(version("1.44"))]
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn foo() -> bool { true }
+#[cfg(not(version("1.44")))]
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn foo() -> bool { false }
+
+#[cfg(version("1.43", "1.44", "1.45"))] //~ ERROR: expected single version literal
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn bar() -> bool  { false }
+#[cfg(version(false))] //~ ERROR: expected a version literal
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn bar() -> bool  { false }
+#[cfg(version("foo"))] //~ WARNING: unknown version literal format
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn bar() -> bool  { false }
+#[cfg(version("999"))] //~ WARNING: unknown version literal format
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn bar() -> bool  { false }
+#[cfg(version("-1"))] //~ WARNING: unknown version literal format
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn bar() -> bool  { false }
+#[cfg(version("65536"))] //~ WARNING: unknown version literal format
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn bar() -> bool  { false }
+#[cfg(version("0"))] //~ WARNING: unknown version literal format
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn bar() -> bool { true }
+#[cfg(version("1.0"))]
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn bar() -> bool { true }
+#[cfg(version("1.65536.2"))] //~ WARNING: unknown version literal format
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn bar() -> bool  { false }
+#[cfg(version("1.20.0-stable"))] //~ WARNING: unknown version literal format
+//~^ ERROR `cfg(version)` is experimental and subject to change
+fn bar() {}
+
+fn main() {
+    assert!(foo());
+    assert!(bar());
+    assert!(cfg!(version("1.42"))); //~ ERROR `cfg(version)` is experimental and subject to change
+}
diff --git a/tests/ui/feature-gates/feature-gate-cfg-version.stderr b/tests/ui/feature-gates/feature-gate-cfg-version.stderr
new file mode 100644
index 000000000..ae899d409
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg-version.stderr
@@ -0,0 +1,204 @@
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:1:7
+   |
+LL | #[cfg(version(42))]
+   |       ^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+error: expected a version literal
+  --> $DIR/feature-gate-cfg-version.rs:1:15
+   |
+LL | #[cfg(version(42))]
+   |               ^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:4:7
+   |
+LL | #[cfg(version(1.20))]
+   |       ^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+error: expected a version literal
+  --> $DIR/feature-gate-cfg-version.rs:4:15
+   |
+LL | #[cfg(version(1.20))]
+   |               ^^^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:7:7
+   |
+LL | #[cfg(version("1.44"))]
+   |       ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:10:11
+   |
+LL | #[cfg(not(version("1.44")))]
+   |           ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:14:7
+   |
+LL | #[cfg(version("1.43", "1.44", "1.45"))]
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+error: expected single version literal
+  --> $DIR/feature-gate-cfg-version.rs:14:7
+   |
+LL | #[cfg(version("1.43", "1.44", "1.45"))]
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:17:7
+   |
+LL | #[cfg(version(false))]
+   |       ^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+error: expected a version literal
+  --> $DIR/feature-gate-cfg-version.rs:17:15
+   |
+LL | #[cfg(version(false))]
+   |               ^^^^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:20:7
+   |
+LL | #[cfg(version("foo"))]
+   |       ^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/feature-gate-cfg-version.rs:20:15
+   |
+LL | #[cfg(version("foo"))]
+   |               ^^^^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:23:7
+   |
+LL | #[cfg(version("999"))]
+   |       ^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/feature-gate-cfg-version.rs:23:15
+   |
+LL | #[cfg(version("999"))]
+   |               ^^^^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:26:7
+   |
+LL | #[cfg(version("-1"))]
+   |       ^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/feature-gate-cfg-version.rs:26:15
+   |
+LL | #[cfg(version("-1"))]
+   |               ^^^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:29:7
+   |
+LL | #[cfg(version("65536"))]
+   |       ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/feature-gate-cfg-version.rs:29:15
+   |
+LL | #[cfg(version("65536"))]
+   |               ^^^^^^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:32:7
+   |
+LL | #[cfg(version("0"))]
+   |       ^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/feature-gate-cfg-version.rs:32:15
+   |
+LL | #[cfg(version("0"))]
+   |               ^^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:35:7
+   |
+LL | #[cfg(version("1.0"))]
+   |       ^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:38:7
+   |
+LL | #[cfg(version("1.65536.2"))]
+   |       ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/feature-gate-cfg-version.rs:38:15
+   |
+LL | #[cfg(version("1.65536.2"))]
+   |               ^^^^^^^^^^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:41:7
+   |
+LL | #[cfg(version("1.20.0-stable"))]
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+warning: unknown version literal format, assuming it refers to a future version
+  --> $DIR/feature-gate-cfg-version.rs:41:15
+   |
+LL | #[cfg(version("1.20.0-stable"))]
+   |               ^^^^^^^^^^^^^^^
+
+error[E0658]: `cfg(version)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg-version.rs:48:18
+   |
+LL |     assert!(cfg!(version("1.42")));
+   |                  ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #64796 <https://github.com/rust-lang/rust/issues/64796> for more information
+   = help: add `#![feature(cfg_version)]` to the crate attributes to enable
+
+error: aborting due to 19 previous errors; 7 warnings emitted
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-cfg_sanitize.rs b/tests/ui/feature-gates/feature-gate-cfg_sanitize.rs
new file mode 100644
index 000000000..c3e7cc9ed
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg_sanitize.rs
@@ -0,0 +1,3 @@
+#[cfg(not(sanitize = "thread"))]
+//~^ `cfg(sanitize)` is experimental
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-cfg_sanitize.stderr b/tests/ui/feature-gates/feature-gate-cfg_sanitize.stderr
new file mode 100644
index 000000000..8088585da
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-cfg_sanitize.stderr
@@ -0,0 +1,12 @@
+error[E0658]: `cfg(sanitize)` is experimental and subject to change
+  --> $DIR/feature-gate-cfg_sanitize.rs:1:11
+   |
+LL | #[cfg(not(sanitize = "thread"))]
+   |           ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #39699 <https://github.com/rust-lang/rust/issues/39699> for more information
+   = help: add `#![feature(cfg_sanitize)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-check-cfg.rs b/tests/ui/feature-gates/feature-gate-check-cfg.rs
new file mode 100644
index 000000000..4012a3b04
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-check-cfg.rs
@@ -0,0 +1,3 @@
+// compile-flags: --check-cfg "names()"
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-check-cfg.stderr b/tests/ui/feature-gates/feature-gate-check-cfg.stderr
new file mode 100644
index 000000000..9b27c2bc0
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-check-cfg.stderr
@@ -0,0 +1,2 @@
+error: the `-Z unstable-options` flag must also be passed to enable the flag `check-cfg`
+
diff --git a/tests/ui/feature-gates/feature-gate-closure_lifetime_binder.rs b/tests/ui/feature-gates/feature-gate-closure_lifetime_binder.rs
new file mode 100644
index 000000000..b0b494fa3
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-closure_lifetime_binder.rs
@@ -0,0 +1,8 @@
+fn main() {
+    for<> || -> () {};
+    //~^ ERROR `for<...>` binders for closures are experimental
+    for<'a> || -> () {};
+    //~^ ERROR `for<...>` binders for closures are experimental
+    for<'a, 'b> |_: &'a ()| -> () {};
+    //~^ ERROR `for<...>` binders for closures are experimental
+}
diff --git a/tests/ui/feature-gates/feature-gate-closure_lifetime_binder.stderr b/tests/ui/feature-gates/feature-gate-closure_lifetime_binder.stderr
new file mode 100644
index 000000000..aea5cfeed
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-closure_lifetime_binder.stderr
@@ -0,0 +1,33 @@
+error[E0658]: `for<...>` binders for closures are experimental
+  --> $DIR/feature-gate-closure_lifetime_binder.rs:2:5
+   |
+LL |     for<> || -> () {};
+   |     ^^^^^
+   |
+   = note: see issue #97362 <https://github.com/rust-lang/rust/issues/97362> for more information
+   = help: add `#![feature(closure_lifetime_binder)]` to the crate attributes to enable
+   = help: consider removing `for<...>`
+
+error[E0658]: `for<...>` binders for closures are experimental
+  --> $DIR/feature-gate-closure_lifetime_binder.rs:4:5
+   |
+LL |     for<'a> || -> () {};
+   |     ^^^^^^^
+   |
+   = note: see issue #97362 <https://github.com/rust-lang/rust/issues/97362> for more information
+   = help: add `#![feature(closure_lifetime_binder)]` to the crate attributes to enable
+   = help: consider removing `for<...>`
+
+error[E0658]: `for<...>` binders for closures are experimental
+  --> $DIR/feature-gate-closure_lifetime_binder.rs:6:5
+   |
+LL |     for<'a, 'b> |_: &'a ()| -> () {};
+   |     ^^^^^^^^^^^
+   |
+   = note: see issue #97362 <https://github.com/rust-lang/rust/issues/97362> for more information
+   = help: add `#![feature(closure_lifetime_binder)]` to the crate attributes to enable
+   = help: consider removing `for<...>`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-closure_track_caller.rs b/tests/ui/feature-gates/feature-gate-closure_track_caller.rs
new file mode 100644
index 000000000..a8d63a814
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-closure_track_caller.rs
@@ -0,0 +1,7 @@
+#![feature(stmt_expr_attributes)]
+#![feature(generators)]
+
+fn main() {
+    let _closure = #[track_caller] || {}; //~ `#[track_caller]` on closures
+    let _generator = #[track_caller] || { yield; }; //~ `#[track_caller]` on closures
+}
diff --git a/tests/ui/feature-gates/feature-gate-closure_track_caller.stderr b/tests/ui/feature-gates/feature-gate-closure_track_caller.stderr
new file mode 100644
index 000000000..ed63d74fe
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-closure_track_caller.stderr
@@ -0,0 +1,21 @@
+error[E0658]: `#[track_caller]` on closures is currently unstable
+  --> $DIR/feature-gate-closure_track_caller.rs:5:20
+   |
+LL |     let _closure = #[track_caller] || {};
+   |                    ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #87417 <https://github.com/rust-lang/rust/issues/87417> for more information
+   = help: add `#![feature(closure_track_caller)]` to the crate attributes to enable
+
+error[E0658]: `#[track_caller]` on closures is currently unstable
+  --> $DIR/feature-gate-closure_track_caller.rs:6:22
+   |
+LL |     let _generator = #[track_caller] || { yield; };
+   |                      ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #87417 <https://github.com/rust-lang/rust/issues/87417> for more information
+   = help: add `#![feature(closure_track_caller)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-collapse_debuginfo.rs b/tests/ui/feature-gates/feature-gate-collapse_debuginfo.rs
new file mode 100644
index 000000000..f73bf579f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-collapse_debuginfo.rs
@@ -0,0 +1,7 @@
+#[collapse_debuginfo]
+//~^ ERROR the `#[collapse_debuginfo]` attribute is an experimental feature
+macro_rules! foo {
+    ($e:expr) => { $e }
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-collapse_debuginfo.stderr b/tests/ui/feature-gates/feature-gate-collapse_debuginfo.stderr
new file mode 100644
index 000000000..2cbde893a
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-collapse_debuginfo.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[collapse_debuginfo]` attribute is an experimental feature
+  --> $DIR/feature-gate-collapse_debuginfo.rs:1:1
+   |
+LL | #[collapse_debuginfo]
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #100758 <https://github.com/rust-lang/rust/issues/100758> for more information
+   = help: add `#![feature(collapse_debuginfo)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-compiler-builtins.rs b/tests/ui/feature-gates/feature-gate-compiler-builtins.rs
new file mode 100644
index 000000000..0d64f1fdc
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-compiler-builtins.rs
@@ -0,0 +1,3 @@
+#![compiler_builtins] //~ ERROR the `#[compiler_builtins]` attribute is
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-compiler-builtins.stderr b/tests/ui/feature-gates/feature-gate-compiler-builtins.stderr
new file mode 100644
index 000000000..9d04aef86
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-compiler-builtins.stderr
@@ -0,0 +1,11 @@
+error[E0658]: the `#[compiler_builtins]` attribute is used to identify the `compiler_builtins` crate which contains compiler-rt intrinsics and will never be stable
+  --> $DIR/feature-gate-compiler-builtins.rs:1:1
+   |
+LL | #![compiler_builtins]
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(compiler_builtins)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-concat_bytes.rs b/tests/ui/feature-gates/feature-gate-concat_bytes.rs
new file mode 100644
index 000000000..07d63cb11
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-concat_bytes.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let a = concat_bytes!(b'A', b"BC"); //~ ERROR use of unstable library feature 'concat_bytes'
+    assert_eq!(a, &[65, 66, 67]);
+}
diff --git a/tests/ui/feature-gates/feature-gate-concat_bytes.stderr b/tests/ui/feature-gates/feature-gate-concat_bytes.stderr
new file mode 100644
index 000000000..4b3ee4c19
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-concat_bytes.stderr
@@ -0,0 +1,12 @@
+error[E0658]: use of unstable library feature 'concat_bytes'
+  --> $DIR/feature-gate-concat_bytes.rs:2:13
+   |
+LL |     let a = concat_bytes!(b'A', b"BC");
+   |             ^^^^^^^^^^^^
+   |
+   = note: see issue #87555 <https://github.com/rust-lang/rust/issues/87555> for more information
+   = help: add `#![feature(concat_bytes)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-concat_idents.rs b/tests/ui/feature-gates/feature-gate-concat_idents.rs
new file mode 100644
index 000000000..68caf3d71
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-concat_idents.rs
@@ -0,0 +1,9 @@
+const XY_1: i32 = 10;
+
+fn main() {
+    const XY_2: i32 = 20;
+    let a = concat_idents!(X, Y_1); //~ ERROR `concat_idents` is not stable
+    let b = concat_idents!(X, Y_2); //~ ERROR `concat_idents` is not stable
+    assert_eq!(a, 10);
+    assert_eq!(b, 20);
+}
diff --git a/tests/ui/feature-gates/feature-gate-concat_idents.stderr b/tests/ui/feature-gates/feature-gate-concat_idents.stderr
new file mode 100644
index 000000000..0454fd494
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-concat_idents.stderr
@@ -0,0 +1,21 @@
+error[E0658]: use of unstable library feature 'concat_idents': `concat_idents` is not stable enough for use and is subject to change
+  --> $DIR/feature-gate-concat_idents.rs:5:13
+   |
+LL |     let a = concat_idents!(X, Y_1);
+   |             ^^^^^^^^^^^^^
+   |
+   = note: see issue #29599 <https://github.com/rust-lang/rust/issues/29599> for more information
+   = help: add `#![feature(concat_idents)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'concat_idents': `concat_idents` is not stable enough for use and is subject to change
+  --> $DIR/feature-gate-concat_idents.rs:6:13
+   |
+LL |     let b = concat_idents!(X, Y_2);
+   |             ^^^^^^^^^^^^^
+   |
+   = note: see issue #29599 <https://github.com/rust-lang/rust/issues/29599> for more information
+   = help: add `#![feature(concat_idents)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-concat_idents2.rs b/tests/ui/feature-gates/feature-gate-concat_idents2.rs
new file mode 100644
index 000000000..9660ffeaf
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-concat_idents2.rs
@@ -0,0 +1,4 @@
+fn main() {
+    concat_idents!(a, b); //~ ERROR `concat_idents` is not stable enough
+                          //~| ERROR cannot find value `ab` in this scope
+}
diff --git a/tests/ui/feature-gates/feature-gate-concat_idents2.stderr b/tests/ui/feature-gates/feature-gate-concat_idents2.stderr
new file mode 100644
index 000000000..8663bc7ca
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-concat_idents2.stderr
@@ -0,0 +1,21 @@
+error[E0658]: use of unstable library feature 'concat_idents': `concat_idents` is not stable enough for use and is subject to change
+  --> $DIR/feature-gate-concat_idents2.rs:2:5
+   |
+LL |     concat_idents!(a, b);
+   |     ^^^^^^^^^^^^^
+   |
+   = note: see issue #29599 <https://github.com/rust-lang/rust/issues/29599> for more information
+   = help: add `#![feature(concat_idents)]` to the crate attributes to enable
+
+error[E0425]: cannot find value `ab` in this scope
+  --> $DIR/feature-gate-concat_idents2.rs:2:5
+   |
+LL |     concat_idents!(a, b);
+   |     ^^^^^^^^^^^^^^^^^^^^ not found in this scope
+   |
+   = note: this error originates in the macro `concat_idents` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0425, E0658.
+For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/feature-gates/feature-gate-concat_idents3.rs b/tests/ui/feature-gates/feature-gate-concat_idents3.rs
new file mode 100644
index 000000000..81710fd9f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-concat_idents3.rs
@@ -0,0 +1,7 @@
+const XY_1: i32 = 10;
+
+fn main() {
+    const XY_2: i32 = 20;
+    assert_eq!(10, concat_idents!(X, Y_1)); //~ ERROR `concat_idents` is not stable
+    assert_eq!(20, concat_idents!(X, Y_2)); //~ ERROR `concat_idents` is not stable
+}
diff --git a/tests/ui/feature-gates/feature-gate-concat_idents3.stderr b/tests/ui/feature-gates/feature-gate-concat_idents3.stderr
new file mode 100644
index 000000000..1316107a3
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-concat_idents3.stderr
@@ -0,0 +1,21 @@
+error[E0658]: use of unstable library feature 'concat_idents': `concat_idents` is not stable enough for use and is subject to change
+  --> $DIR/feature-gate-concat_idents3.rs:5:20
+   |
+LL |     assert_eq!(10, concat_idents!(X, Y_1));
+   |                    ^^^^^^^^^^^^^
+   |
+   = note: see issue #29599 <https://github.com/rust-lang/rust/issues/29599> for more information
+   = help: add `#![feature(concat_idents)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'concat_idents': `concat_idents` is not stable enough for use and is subject to change
+  --> $DIR/feature-gate-concat_idents3.rs:6:20
+   |
+LL |     assert_eq!(20, concat_idents!(X, Y_2));
+   |                    ^^^^^^^^^^^^^
+   |
+   = note: see issue #29599 <https://github.com/rust-lang/rust/issues/29599> for more information
+   = help: add `#![feature(concat_idents)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-const-indexing.rs b/tests/ui/feature-gates/feature-gate-const-indexing.rs
new file mode 100644
index 000000000..2b1067b34
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-const-indexing.rs
@@ -0,0 +1,8 @@
+// build-pass (FIXME(62277): could be check-pass?)
+
+fn main() {
+    const ARR: [i32; 6] = [42, 43, 44, 45, 46, 47];
+    const IDX: usize = 3;
+    const VAL: i32 = ARR[IDX];
+    const BLUB: [i32; (ARR[0] - 41) as usize] = [5];
+}
diff --git a/tests/ui/feature-gates/feature-gate-const_refs_to_cell.rs b/tests/ui/feature-gates/feature-gate-const_refs_to_cell.rs
new file mode 100644
index 000000000..63159ed05
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-const_refs_to_cell.rs
@@ -0,0 +1,12 @@
+// check-pass
+
+#![feature(const_refs_to_cell)]
+
+const FOO: () = {
+    let x = std::cell::Cell::new(42);
+    let y = &x;
+};
+
+fn main() {
+    FOO;
+}
diff --git a/tests/ui/feature-gates/feature-gate-custom_attribute.rs b/tests/ui/feature-gates/feature-gate-custom_attribute.rs
new file mode 100644
index 000000000..936cab268
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-custom_attribute.rs
@@ -0,0 +1,18 @@
+// Check that literals in attributes parse just fine.
+
+#[fake_attr] //~ ERROR cannot find attribute `fake_attr` in this scope
+#[fake_attr(100)] //~ ERROR cannot find attribute `fake_attr` in this scope
+#[fake_attr(1, 2, 3)] //~ ERROR cannot find attribute `fake_attr` in this scope
+#[fake_attr("hello")] //~ ERROR cannot find attribute `fake_attr` in this scope
+#[fake_attr(name = "hello")] //~ ERROR cannot find attribute `fake_attr` in this scope
+#[fake_attr(1, "hi", key = 12, true, false)] //~ ERROR cannot find attribute `fake_attr` in th
+#[fake_attr(key = "hello", val = 10)] //~ ERROR cannot find attribute `fake_attr` in this scop
+#[fake_attr(key("hello"), val(10))] //~ ERROR cannot find attribute `fake_attr` in this scope
+#[fake_attr(enabled = true, disabled = false)] //~ ERROR cannot find attribute `fake_attr` in
+#[fake_attr(true)] //~ ERROR cannot find attribute `fake_attr` in this scope
+#[fake_attr(pi = 3.14159)] //~ ERROR cannot find attribute `fake_attr` in this scope
+#[fake_attr(b"hi")] //~ ERROR cannot find attribute `fake_attr` in this scope
+#[fake_doc(r"doc")] //~ ERROR cannot find attribute `fake_doc` in this scope
+struct Q {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-custom_attribute.stderr b/tests/ui/feature-gates/feature-gate-custom_attribute.stderr
new file mode 100644
index 000000000..b7c45ec1f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-custom_attribute.stderr
@@ -0,0 +1,80 @@
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:3:3
+   |
+LL | #[fake_attr]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:4:3
+   |
+LL | #[fake_attr(100)]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:5:3
+   |
+LL | #[fake_attr(1, 2, 3)]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:6:3
+   |
+LL | #[fake_attr("hello")]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:7:3
+   |
+LL | #[fake_attr(name = "hello")]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:8:3
+   |
+LL | #[fake_attr(1, "hi", key = 12, true, false)]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:9:3
+   |
+LL | #[fake_attr(key = "hello", val = 10)]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:10:3
+   |
+LL | #[fake_attr(key("hello"), val(10))]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:11:3
+   |
+LL | #[fake_attr(enabled = true, disabled = false)]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:12:3
+   |
+LL | #[fake_attr(true)]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:13:3
+   |
+LL | #[fake_attr(pi = 3.14159)]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_attr` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:14:3
+   |
+LL | #[fake_attr(b"hi")]
+   |   ^^^^^^^^^
+
+error: cannot find attribute `fake_doc` in this scope
+  --> $DIR/feature-gate-custom_attribute.rs:15:3
+   |
+LL | #[fake_doc(r"doc")]
+   |   ^^^^^^^^
+
+error: aborting due to 13 previous errors
+
diff --git a/tests/ui/feature-gates/feature-gate-custom_attribute2.rs b/tests/ui/feature-gates/feature-gate-custom_attribute2.rs
new file mode 100644
index 000000000..724e53deb
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-custom_attribute2.rs
@@ -0,0 +1,58 @@
+// This test ensures that attributes on formals in generic parameter
+// lists are included when we are checking for unstable attributes.
+
+struct StLt<#[lt_struct] 'a>(&'a u32);
+//~^ ERROR cannot find attribute `lt_struct` in this scope
+struct StTy<#[ty_struct] I>(I);
+//~^ ERROR cannot find attribute `ty_struct` in this scope
+
+enum EnLt<#[lt_enum] 'b> { A(&'b u32), B }
+//~^ ERROR cannot find attribute `lt_enum` in this scope
+enum EnTy<#[ty_enum] J> { A(J), B }
+//~^ ERROR cannot find attribute `ty_enum` in this scope
+
+trait TrLt<#[lt_trait] 'c> { fn foo(&self, _: &'c [u32]) -> &'c u32; }
+//~^ ERROR cannot find attribute `lt_trait` in this scope
+trait TrTy<#[ty_trait] K> { fn foo(&self, _: K); }
+//~^ ERROR cannot find attribute `ty_trait` in this scope
+
+type TyLt<#[lt_type] 'd> = &'d u32;
+//~^ ERROR cannot find attribute `lt_type` in this scope
+type TyTy<#[ty_type] L> = (L, );
+//~^ ERROR cannot find attribute `ty_type` in this scope
+
+impl<#[lt_inherent] 'e> StLt<'e> { }
+//~^ ERROR cannot find attribute `lt_inherent` in this scope
+impl<#[ty_inherent] M> StTy<M> { }
+//~^ ERROR cannot find attribute `ty_inherent` in this scope
+
+impl<#[lt_impl_for] 'f> TrLt<'f> for StLt<'f> {
+    //~^ ERROR cannot find attribute `lt_impl_for` in this scope
+    fn foo(&self, _: &'f [u32]) -> &'f u32 { loop { } }
+}
+impl<#[ty_impl_for] N> TrTy<N> for StTy<N> {
+    //~^ ERROR cannot find attribute `ty_impl_for` in this scope
+    fn foo(&self, _: N) { }
+}
+
+fn f_lt<#[lt_fn] 'g>(_: &'g [u32]) -> &'g u32 { loop { } }
+//~^ ERROR cannot find attribute `lt_fn` in this scope
+fn f_ty<#[ty_fn] O>(_: O) { }
+//~^ ERROR cannot find attribute `ty_fn` in this scope
+
+impl<I> StTy<I> {
+    fn m_lt<#[lt_meth] 'h>(_: &'h [u32]) -> &'h u32 { loop { } }
+    //~^ ERROR cannot find attribute `lt_meth` in this scope
+    fn m_ty<#[ty_meth] P>(_: P) { }
+    //~^ ERROR cannot find attribute `ty_meth` in this scope
+}
+
+fn hof_lt<Q>(_: Q)
+    where Q: for <#[lt_hof] 'i> Fn(&'i [u32]) -> &'i u32
+    //~^ ERROR cannot find attribute `lt_hof` in this scope
+{
+}
+
+fn main() {
+
+}
diff --git a/tests/ui/feature-gates/feature-gate-custom_attribute2.stderr b/tests/ui/feature-gates/feature-gate-custom_attribute2.stderr
new file mode 100644
index 000000000..f22871117
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-custom_attribute2.stderr
@@ -0,0 +1,104 @@
+error: cannot find attribute `lt_struct` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:4:15
+   |
+LL | struct StLt<#[lt_struct] 'a>(&'a u32);
+   |               ^^^^^^^^^
+
+error: cannot find attribute `ty_struct` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:6:15
+   |
+LL | struct StTy<#[ty_struct] I>(I);
+   |               ^^^^^^^^^
+
+error: cannot find attribute `lt_enum` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:9:13
+   |
+LL | enum EnLt<#[lt_enum] 'b> { A(&'b u32), B }
+   |             ^^^^^^^
+
+error: cannot find attribute `ty_enum` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:11:13
+   |
+LL | enum EnTy<#[ty_enum] J> { A(J), B }
+   |             ^^^^^^^
+
+error: cannot find attribute `lt_trait` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:14:14
+   |
+LL | trait TrLt<#[lt_trait] 'c> { fn foo(&self, _: &'c [u32]) -> &'c u32; }
+   |              ^^^^^^^^
+
+error: cannot find attribute `ty_trait` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:16:14
+   |
+LL | trait TrTy<#[ty_trait] K> { fn foo(&self, _: K); }
+   |              ^^^^^^^^
+
+error: cannot find attribute `lt_type` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:19:13
+   |
+LL | type TyLt<#[lt_type] 'd> = &'d u32;
+   |             ^^^^^^^
+
+error: cannot find attribute `ty_type` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:21:13
+   |
+LL | type TyTy<#[ty_type] L> = (L, );
+   |             ^^^^^^^
+
+error: cannot find attribute `lt_inherent` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:24:8
+   |
+LL | impl<#[lt_inherent] 'e> StLt<'e> { }
+   |        ^^^^^^^^^^^
+
+error: cannot find attribute `ty_inherent` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:26:8
+   |
+LL | impl<#[ty_inherent] M> StTy<M> { }
+   |        ^^^^^^^^^^^
+
+error: cannot find attribute `lt_impl_for` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:29:8
+   |
+LL | impl<#[lt_impl_for] 'f> TrLt<'f> for StLt<'f> {
+   |        ^^^^^^^^^^^
+
+error: cannot find attribute `ty_impl_for` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:33:8
+   |
+LL | impl<#[ty_impl_for] N> TrTy<N> for StTy<N> {
+   |        ^^^^^^^^^^^
+
+error: cannot find attribute `lt_fn` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:38:11
+   |
+LL | fn f_lt<#[lt_fn] 'g>(_: &'g [u32]) -> &'g u32 { loop { } }
+   |           ^^^^^
+
+error: cannot find attribute `ty_fn` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:40:11
+   |
+LL | fn f_ty<#[ty_fn] O>(_: O) { }
+   |           ^^^^^
+
+error: cannot find attribute `lt_meth` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:44:15
+   |
+LL |     fn m_lt<#[lt_meth] 'h>(_: &'h [u32]) -> &'h u32 { loop { } }
+   |               ^^^^^^^
+
+error: cannot find attribute `ty_meth` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:46:15
+   |
+LL |     fn m_ty<#[ty_meth] P>(_: P) { }
+   |               ^^^^^^^
+
+error: cannot find attribute `lt_hof` in this scope
+  --> $DIR/feature-gate-custom_attribute2.rs:51:21
+   |
+LL |     where Q: for <#[lt_hof] 'i> Fn(&'i [u32]) -> &'i u32
+   |                     ^^^^^^
+
+error: aborting due to 17 previous errors
+
diff --git a/tests/ui/feature-gates/feature-gate-custom_mir.rs b/tests/ui/feature-gates/feature-gate-custom_mir.rs
new file mode 100644
index 000000000..0126dde2f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-custom_mir.rs
@@ -0,0 +1,12 @@
+#![feature(core_intrinsics)]
+
+extern crate core;
+
+#[custom_mir(dialect = "built")] //~ ERROR the `#[custom_mir]` attribute is just used for the Rust test suite
+pub fn foo(_x: i32) -> i32 {
+    0
+}
+
+fn main() {
+    assert_eq!(2, foo(2));
+}
diff --git a/tests/ui/feature-gates/feature-gate-custom_mir.stderr b/tests/ui/feature-gates/feature-gate-custom_mir.stderr
new file mode 100644
index 000000000..3c149d30d
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-custom_mir.stderr
@@ -0,0 +1,11 @@
+error[E0658]: the `#[custom_mir]` attribute is just used for the Rust test suite
+  --> $DIR/feature-gate-custom_mir.rs:5:1
+   |
+LL | #[custom_mir(dialect = "built")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(custom_mir)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-custom_test_frameworks.rs b/tests/ui/feature-gates/feature-gate-custom_test_frameworks.rs
new file mode 100644
index 000000000..83bb153ba
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-custom_test_frameworks.rs
@@ -0,0 +1,6 @@
+#![test_runner(main)] //~ ERROR custom test frameworks are an unstable feature
+
+#[test_case] //~ ERROR custom test frameworks are an unstable feature
+fn f() {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-custom_test_frameworks.stderr b/tests/ui/feature-gates/feature-gate-custom_test_frameworks.stderr
new file mode 100644
index 000000000..b65b009a3
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-custom_test_frameworks.stderr
@@ -0,0 +1,21 @@
+error[E0658]: use of unstable library feature 'custom_test_frameworks': custom test frameworks are an unstable feature
+  --> $DIR/feature-gate-custom_test_frameworks.rs:3:3
+   |
+LL | #[test_case]
+   |   ^^^^^^^^^
+   |
+   = note: see issue #50297 <https://github.com/rust-lang/rust/issues/50297> for more information
+   = help: add `#![feature(custom_test_frameworks)]` to the crate attributes to enable
+
+error[E0658]: custom test frameworks are an unstable feature
+  --> $DIR/feature-gate-custom_test_frameworks.rs:1:1
+   |
+LL | #![test_runner(main)]
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #50297 <https://github.com/rust-lang/rust/issues/50297> for more information
+   = help: add `#![feature(custom_test_frameworks)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-debugger-visualizer.rs b/tests/ui/feature-gates/feature-gate-debugger-visualizer.rs
new file mode 100644
index 000000000..4c4dc450d
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-debugger-visualizer.rs
@@ -0,0 +1,3 @@
+#![debugger_visualizer(natvis_file = "auxiliary/debugger-visualizer.natvis")] //~ ERROR the `#[debugger_visualizer]` attribute is an experimental feature
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-debugger-visualizer.stderr b/tests/ui/feature-gates/feature-gate-debugger-visualizer.stderr
new file mode 100644
index 000000000..e9367fbc6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-debugger-visualizer.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[debugger_visualizer]` attribute is an experimental feature
+  --> $DIR/feature-gate-debugger-visualizer.rs:1:1
+   |
+LL | #![debugger_visualizer(natvis_file = "auxiliary/debugger-visualizer.natvis")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #95939 <https://github.com/rust-lang/rust/issues/95939> for more information
+   = help: add `#![feature(debugger_visualizer)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-decl_macro.rs b/tests/ui/feature-gates/feature-gate-decl_macro.rs
new file mode 100644
index 000000000..d002c5dbb
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-decl_macro.rs
@@ -0,0 +1,5 @@
+#![allow(unused_macros)]
+
+macro m() {} //~ ERROR `macro` is experimental
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-decl_macro.stderr b/tests/ui/feature-gates/feature-gate-decl_macro.stderr
new file mode 100644
index 000000000..800caf252
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-decl_macro.stderr
@@ -0,0 +1,12 @@
+error[E0658]: `macro` is experimental
+  --> $DIR/feature-gate-decl_macro.rs:3:1
+   |
+LL | macro m() {}
+   | ^^^^^^^^^^^^
+   |
+   = note: see issue #39412 <https://github.com/rust-lang/rust/issues/39412> for more information
+   = help: add `#![feature(decl_macro)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-default_type_parameter_fallback.rs b/tests/ui/feature-gates/feature-gate-default_type_parameter_fallback.rs
new file mode 100644
index 000000000..33038e24b
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-default_type_parameter_fallback.rs
@@ -0,0 +1,12 @@
+#![allow(unused)]
+
+fn avg<T=i32>(_: T) {}
+//~^ ERROR defaults for type parameters are only allowed
+//~| WARN this was previously accepted
+
+struct S<T>(T);
+impl<T=i32> S<T> {}
+//~^ ERROR defaults for type parameters are only allowed
+//~| WARN this was previously accepted
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-default_type_parameter_fallback.stderr b/tests/ui/feature-gates/feature-gate-default_type_parameter_fallback.stderr
new file mode 100644
index 000000000..308de2692
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-default_type_parameter_fallback.stderr
@@ -0,0 +1,21 @@
+error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
+  --> $DIR/feature-gate-default_type_parameter_fallback.rs:3:8
+   |
+LL | fn avg<T=i32>(_: T) {}
+   |        ^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #36887 <https://github.com/rust-lang/rust/issues/36887>
+   = note: `#[deny(invalid_type_param_default)]` on by default
+
+error: defaults for type parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
+  --> $DIR/feature-gate-default_type_parameter_fallback.rs:8:6
+   |
+LL | impl<T=i32> S<T> {}
+   |      ^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #36887 <https://github.com/rust-lang/rust/issues/36887>
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/feature-gates/feature-gate-deprecated_safe.rs b/tests/ui/feature-gates/feature-gate-deprecated_safe.rs
new file mode 100644
index 000000000..d5f4a4705
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-deprecated_safe.rs
@@ -0,0 +1,7 @@
+#[deprecated_safe(since = "TBD", note = "...")] //~ ERROR: the `#[deprecated_safe]` attribute is an experimental feature
+unsafe fn deprecated_safe_fn() {}
+
+#[deprecated_safe(since = "TBD", note = "...")] //~ ERROR: the `#[deprecated_safe]` attribute is an experimental feature
+unsafe trait DeprecatedSafeTrait {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-deprecated_safe.stderr b/tests/ui/feature-gates/feature-gate-deprecated_safe.stderr
new file mode 100644
index 000000000..5e98a1faa
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-deprecated_safe.stderr
@@ -0,0 +1,21 @@
+error[E0658]: the `#[deprecated_safe]` attribute is an experimental feature
+  --> $DIR/feature-gate-deprecated_safe.rs:1:1
+   |
+LL | #[deprecated_safe(since = "TBD", note = "...")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #94978 <https://github.com/rust-lang/rust/issues/94978> for more information
+   = help: add `#![feature(deprecated_safe)]` to the crate attributes to enable
+
+error[E0658]: the `#[deprecated_safe]` attribute is an experimental feature
+  --> $DIR/feature-gate-deprecated_safe.rs:4:1
+   |
+LL | #[deprecated_safe(since = "TBD", note = "...")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #94978 <https://github.com/rust-lang/rust/issues/94978> for more information
+   = help: add `#![feature(deprecated_safe)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-doc_cfg.rs b/tests/ui/feature-gates/feature-gate-doc_cfg.rs
new file mode 100644
index 000000000..b12b8a105
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-doc_cfg.rs
@@ -0,0 +1,2 @@
+#[doc(cfg(unix))] //~ ERROR: `#[doc(cfg)]` is experimental
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-doc_cfg.stderr b/tests/ui/feature-gates/feature-gate-doc_cfg.stderr
new file mode 100644
index 000000000..fe88e08c1
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-doc_cfg.stderr
@@ -0,0 +1,12 @@
+error[E0658]: `#[doc(cfg)]` is experimental
+  --> $DIR/feature-gate-doc_cfg.rs:1:1
+   |
+LL | #[doc(cfg(unix))]
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #43781 <https://github.com/rust-lang/rust/issues/43781> for more information
+   = help: add `#![feature(doc_cfg)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-doc_masked.rs b/tests/ui/feature-gates/feature-gate-doc_masked.rs
new file mode 100644
index 000000000..bde3af6b5
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-doc_masked.rs
@@ -0,0 +1,4 @@
+#[doc(masked)] //~ ERROR: `#[doc(masked)]` is experimental
+extern crate std as realstd;
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-doc_masked.stderr b/tests/ui/feature-gates/feature-gate-doc_masked.stderr
new file mode 100644
index 000000000..80522b6ee
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-doc_masked.stderr
@@ -0,0 +1,12 @@
+error[E0658]: `#[doc(masked)]` is experimental
+  --> $DIR/feature-gate-doc_masked.rs:1:1
+   |
+LL | #[doc(masked)]
+   | ^^^^^^^^^^^^^^
+   |
+   = note: see issue #44027 <https://github.com/rust-lang/rust/issues/44027> for more information
+   = help: add `#![feature(doc_masked)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-doc_notable_trait.rs b/tests/ui/feature-gates/feature-gate-doc_notable_trait.rs
new file mode 100644
index 000000000..7f3392ead
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-doc_notable_trait.rs
@@ -0,0 +1,4 @@
+#[doc(notable_trait)] //~ ERROR: `#[doc(notable_trait)]` is experimental
+trait SomeTrait {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-doc_notable_trait.stderr b/tests/ui/feature-gates/feature-gate-doc_notable_trait.stderr
new file mode 100644
index 000000000..1f9bef40c
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-doc_notable_trait.stderr
@@ -0,0 +1,12 @@
+error[E0658]: `#[doc(notable_trait)]` is experimental
+  --> $DIR/feature-gate-doc_notable_trait.rs:1:1
+   |
+LL | #[doc(notable_trait)]
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #45040 <https://github.com/rust-lang/rust/issues/45040> for more information
+   = help: add `#![feature(doc_notable_trait)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-exclusive-range-pattern.rs b/tests/ui/feature-gates/feature-gate-exclusive-range-pattern.rs
new file mode 100644
index 000000000..ded08b93f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-exclusive-range-pattern.rs
@@ -0,0 +1,6 @@
+pub fn main() {
+    match 22 {
+        0 .. 3 => {} //~ ERROR exclusive range pattern syntax is experimental
+        _ => {}
+    }
+}
diff --git a/tests/ui/feature-gates/feature-gate-exclusive-range-pattern.stderr b/tests/ui/feature-gates/feature-gate-exclusive-range-pattern.stderr
new file mode 100644
index 000000000..6d7f4844a
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-exclusive-range-pattern.stderr
@@ -0,0 +1,12 @@
+error[E0658]: exclusive range pattern syntax is experimental
+  --> $DIR/feature-gate-exclusive-range-pattern.rs:3:9
+   |
+LL |         0 .. 3 => {}
+   |         ^^^^^^
+   |
+   = note: see issue #37854 <https://github.com/rust-lang/rust/issues/37854> for more information
+   = help: add `#![feature(exclusive_range_pattern)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-exhaustive-patterns.rs b/tests/ui/feature-gates/feature-gate-exhaustive-patterns.rs
new file mode 100644
index 000000000..f0cc9ea70
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-exhaustive-patterns.rs
@@ -0,0 +1,9 @@
+#![feature(never_type)]
+
+fn foo() -> Result<u32, !> {
+    Ok(123)
+}
+
+fn main() {
+    let Ok(_x) = foo(); //~ ERROR refutable pattern in local binding
+}
diff --git a/tests/ui/feature-gates/feature-gate-exhaustive-patterns.stderr b/tests/ui/feature-gates/feature-gate-exhaustive-patterns.stderr
new file mode 100644
index 000000000..49e7ab608
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-exhaustive-patterns.stderr
@@ -0,0 +1,17 @@
+error[E0005]: refutable pattern in local binding
+  --> $DIR/feature-gate-exhaustive-patterns.rs:8:9
+   |
+LL |     let Ok(_x) = foo();
+   |         ^^^^^^ pattern `Err(_)` not covered
+   |
+   = note: `let` bindings require an "irrefutable pattern", like a `struct` or an `enum` with only one variant
+   = note: for more information, visit https://doc.rust-lang.org/book/ch18-02-refutability.html
+   = note: the matched value is of type `Result<u32, !>`
+help: you might want to use `let else` to handle the variant that isn't matched
+   |
+LL |     let Ok(_x) = foo() else { todo!() };
+   |                        ++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0005`.
diff --git a/tests/ui/feature-gates/feature-gate-extern_absolute_paths.rs b/tests/ui/feature-gates/feature-gate-extern_absolute_paths.rs
new file mode 100644
index 000000000..cff273ce2
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-extern_absolute_paths.rs
@@ -0,0 +1,5 @@
+use core::default; //~ ERROR unresolved import `core`
+
+fn main() {
+    let _: u8 = ::core::default::Default(); //~ ERROR failed to resolve
+}
diff --git a/tests/ui/feature-gates/feature-gate-extern_absolute_paths.stderr b/tests/ui/feature-gates/feature-gate-extern_absolute_paths.stderr
new file mode 100644
index 000000000..3bae23a4a
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-extern_absolute_paths.stderr
@@ -0,0 +1,20 @@
+error[E0432]: unresolved import `core`
+  --> $DIR/feature-gate-extern_absolute_paths.rs:1:5
+   |
+LL | use core::default;
+   |     ^^^^ maybe a missing crate `core`?
+   |
+   = help: consider adding `extern crate core` to use the `core` crate
+
+error[E0433]: failed to resolve: maybe a missing crate `core`?
+  --> $DIR/feature-gate-extern_absolute_paths.rs:4:19
+   |
+LL |     let _: u8 = ::core::default::Default();
+   |                   ^^^^ maybe a missing crate `core`?
+   |
+   = help: consider adding `extern crate core` to use the `core` crate
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0432, E0433.
+For more information about an error, try `rustc --explain E0432`.
diff --git a/tests/ui/feature-gates/feature-gate-extern_prelude.rs b/tests/ui/feature-gates/feature-gate-extern_prelude.rs
new file mode 100644
index 000000000..237099e79
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-extern_prelude.rs
@@ -0,0 +1 @@
+can-only-test-this-in-run-make-fulldeps //~ ERROR expected one of `!` or `::`, found `-`
diff --git a/tests/ui/feature-gates/feature-gate-extern_prelude.stderr b/tests/ui/feature-gates/feature-gate-extern_prelude.stderr
new file mode 100644
index 000000000..d72e47e9e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-extern_prelude.stderr
@@ -0,0 +1,8 @@
+error: expected one of `!` or `::`, found `-`
+  --> $DIR/feature-gate-extern_prelude.rs:1:4
+   |
+LL | can-only-test-this-in-run-make-fulldeps
+   |    ^ expected one of `!` or `::`
+
+error: aborting due to previous error
+
diff --git a/tests/ui/feature-gates/feature-gate-extern_types.rs b/tests/ui/feature-gates/feature-gate-extern_types.rs
new file mode 100644
index 000000000..103f8eed6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-extern_types.rs
@@ -0,0 +1,5 @@
+extern "C" {
+    type T; //~ ERROR extern types are experimental
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-extern_types.stderr b/tests/ui/feature-gates/feature-gate-extern_types.stderr
new file mode 100644
index 000000000..923fae400
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-extern_types.stderr
@@ -0,0 +1,12 @@
+error[E0658]: extern types are experimental
+  --> $DIR/feature-gate-extern_types.rs:2:5
+   |
+LL |     type T;
+   |     ^^^^^^^
+   |
+   = note: see issue #43467 <https://github.com/rust-lang/rust/issues/43467> for more information
+   = help: add `#![feature(extern_types)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-feature-gate.rs b/tests/ui/feature-gates/feature-gate-feature-gate.rs
new file mode 100644
index 000000000..3c98e16a1
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-feature-gate.rs
@@ -0,0 +1,4 @@
+#![forbid(unstable_features)]
+#![feature(intrinsics)] //~ ERROR unstable feature
+
+fn main() { }
diff --git a/tests/ui/feature-gates/feature-gate-feature-gate.stderr b/tests/ui/feature-gates/feature-gate-feature-gate.stderr
new file mode 100644
index 000000000..ad97741da
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-feature-gate.stderr
@@ -0,0 +1,14 @@
+error: unstable feature
+  --> $DIR/feature-gate-feature-gate.rs:2:12
+   |
+LL | #![feature(intrinsics)]
+   |            ^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/feature-gate-feature-gate.rs:1:11
+   |
+LL | #![forbid(unstable_features)]
+   |           ^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/tests/ui/feature-gates/feature-gate-ffi_const.rs b/tests/ui/feature-gates/feature-gate-ffi_const.rs
new file mode 100644
index 000000000..9f3d783cc
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-ffi_const.rs
@@ -0,0 +1,6 @@
+#![crate_type = "lib"]
+
+extern "C" {
+    #[ffi_const] //~ ERROR the `#[ffi_const]` attribute is an experimental feature
+    pub fn foo();
+}
diff --git a/tests/ui/feature-gates/feature-gate-ffi_const.stderr b/tests/ui/feature-gates/feature-gate-ffi_const.stderr
new file mode 100644
index 000000000..bed6a2ce4
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-ffi_const.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[ffi_const]` attribute is an experimental feature
+  --> $DIR/feature-gate-ffi_const.rs:4:5
+   |
+LL |     #[ffi_const]
+   |     ^^^^^^^^^^^^
+   |
+   = note: see issue #58328 <https://github.com/rust-lang/rust/issues/58328> for more information
+   = help: add `#![feature(ffi_const)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-ffi_pure.rs b/tests/ui/feature-gates/feature-gate-ffi_pure.rs
new file mode 100644
index 000000000..b0dfa01ff
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-ffi_pure.rs
@@ -0,0 +1,6 @@
+#![crate_type = "lib"]
+
+extern "C" {
+    #[ffi_pure] //~ ERROR the `#[ffi_pure]` attribute is an experimental feature
+    pub fn foo();
+}
diff --git a/tests/ui/feature-gates/feature-gate-ffi_pure.stderr b/tests/ui/feature-gates/feature-gate-ffi_pure.stderr
new file mode 100644
index 000000000..2b0308fd6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-ffi_pure.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[ffi_pure]` attribute is an experimental feature
+  --> $DIR/feature-gate-ffi_pure.rs:4:5
+   |
+LL |     #[ffi_pure]
+   |     ^^^^^^^^^^^
+   |
+   = note: see issue #58329 <https://github.com/rust-lang/rust/issues/58329> for more information
+   = help: add `#![feature(ffi_pure)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-ffi_returns_twice.rs b/tests/ui/feature-gates/feature-gate-ffi_returns_twice.rs
new file mode 100644
index 000000000..f35453435
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-ffi_returns_twice.rs
@@ -0,0 +1,6 @@
+#![crate_type = "lib"]
+
+extern "C" {
+    #[ffi_returns_twice] //~ ERROR the `#[ffi_returns_twice]` attribute is an experimental feature
+    pub fn foo();
+}
diff --git a/tests/ui/feature-gates/feature-gate-ffi_returns_twice.stderr b/tests/ui/feature-gates/feature-gate-ffi_returns_twice.stderr
new file mode 100644
index 000000000..3585355ab
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-ffi_returns_twice.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[ffi_returns_twice]` attribute is an experimental feature
+  --> $DIR/feature-gate-ffi_returns_twice.rs:4:5
+   |
+LL |     #[ffi_returns_twice]
+   |     ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #58314 <https://github.com/rust-lang/rust/issues/58314> for more information
+   = help: add `#![feature(ffi_returns_twice)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-fn_align.rs b/tests/ui/feature-gates/feature-gate-fn_align.rs
new file mode 100644
index 000000000..ea873dba2
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-fn_align.rs
@@ -0,0 +1,4 @@
+#![crate_type = "lib"]
+
+#[repr(align(16))] //~ ERROR `repr(align)` attributes on functions are unstable
+fn requires_alignment() {}
diff --git a/tests/ui/feature-gates/feature-gate-fn_align.stderr b/tests/ui/feature-gates/feature-gate-fn_align.stderr
new file mode 100644
index 000000000..5ff124e48
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-fn_align.stderr
@@ -0,0 +1,12 @@
+error[E0658]: `repr(align)` attributes on functions are unstable
+  --> $DIR/feature-gate-fn_align.rs:3:8
+   |
+LL | #[repr(align(16))]
+   |        ^^^^^^^^^
+   |
+   = note: see issue #82232 <https://github.com/rust-lang/rust/issues/82232> for more information
+   = help: add `#![feature(fn_align)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-format_args_nl.rs b/tests/ui/feature-gates/feature-gate-format_args_nl.rs
new file mode 100644
index 000000000..aeee2fbad
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-format_args_nl.rs
@@ -0,0 +1,3 @@
+fn main() {
+    format_args_nl!(""); //~ ERROR `format_args_nl` is only for internal language use
+}
diff --git a/tests/ui/feature-gates/feature-gate-format_args_nl.stderr b/tests/ui/feature-gates/feature-gate-format_args_nl.stderr
new file mode 100644
index 000000000..b211e2f8e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-format_args_nl.stderr
@@ -0,0 +1,11 @@
+error[E0658]: use of unstable library feature 'format_args_nl': `format_args_nl` is only for internal language use and is subject to change
+  --> $DIR/feature-gate-format_args_nl.rs:2:5
+   |
+LL |     format_args_nl!("");
+   |     ^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(format_args_nl)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-fundamental.rs b/tests/ui/feature-gates/feature-gate-fundamental.rs
new file mode 100644
index 000000000..70e013392
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-fundamental.rs
@@ -0,0 +1,4 @@
+#[fundamental] //~ ERROR the `#[fundamental]` attribute is an experimental feature
+struct Fundamental;
+
+fn main() { }
diff --git a/tests/ui/feature-gates/feature-gate-fundamental.stderr b/tests/ui/feature-gates/feature-gate-fundamental.stderr
new file mode 100644
index 000000000..1ae8d9128
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-fundamental.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[fundamental]` attribute is an experimental feature
+  --> $DIR/feature-gate-fundamental.rs:1:1
+   |
+LL | #[fundamental]
+   | ^^^^^^^^^^^^^^
+   |
+   = note: see issue #29635 <https://github.com/rust-lang/rust/issues/29635> for more information
+   = help: add `#![feature(fundamental)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-generators.rs b/tests/ui/feature-gates/feature-gate-generators.rs
new file mode 100644
index 000000000..931fee134
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-generators.rs
@@ -0,0 +1,10 @@
+fn main() {
+    yield true; //~ ERROR yield syntax is experimental
+                //~^ ERROR yield expression outside of generator literal
+}
+
+#[cfg(FALSE)]
+fn foo() {
+    yield; //~ ERROR yield syntax is experimental
+    yield 0; //~ ERROR yield syntax is experimental
+}
diff --git a/tests/ui/feature-gates/feature-gate-generators.stderr b/tests/ui/feature-gates/feature-gate-generators.stderr
new file mode 100644
index 000000000..dfea178a6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-generators.stderr
@@ -0,0 +1,37 @@
+error[E0658]: yield syntax is experimental
+  --> $DIR/feature-gate-generators.rs:2:5
+   |
+LL |     yield true;
+   |     ^^^^^^^^^^
+   |
+   = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
+   = help: add `#![feature(generators)]` to the crate attributes to enable
+
+error[E0658]: yield syntax is experimental
+  --> $DIR/feature-gate-generators.rs:8:5
+   |
+LL |     yield;
+   |     ^^^^^
+   |
+   = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
+   = help: add `#![feature(generators)]` to the crate attributes to enable
+
+error[E0658]: yield syntax is experimental
+  --> $DIR/feature-gate-generators.rs:9:5
+   |
+LL |     yield 0;
+   |     ^^^^^^^
+   |
+   = note: see issue #43122 <https://github.com/rust-lang/rust/issues/43122> for more information
+   = help: add `#![feature(generators)]` to the crate attributes to enable
+
+error[E0627]: yield expression outside of generator literal
+  --> $DIR/feature-gate-generators.rs:2:5
+   |
+LL |     yield true;
+   |     ^^^^^^^^^^
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0627, E0658.
+For more information about an error, try `rustc --explain E0627`.
diff --git a/tests/ui/feature-gates/feature-gate-generic_arg_infer.normal.stderr b/tests/ui/feature-gates/feature-gate-generic_arg_infer.normal.stderr
new file mode 100644
index 000000000..56123a983
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-generic_arg_infer.normal.stderr
@@ -0,0 +1,43 @@
+error: in expressions, `_` can only be used on the left-hand side of an assignment
+  --> $DIR/feature-gate-generic_arg_infer.rs:11:27
+   |
+LL |     let _x: [u8; 3] = [0; _];
+   |                           ^ `_` not allowed here
+
+error: in expressions, `_` can only be used on the left-hand side of an assignment
+  --> $DIR/feature-gate-generic_arg_infer.rs:14:18
+   |
+LL |     let _y: [u8; _] = [0; 3];
+   |                  ^ `_` not allowed here
+
+error[E0658]: using `_` for array lengths is unstable
+  --> $DIR/feature-gate-generic_arg_infer.rs:14:18
+   |
+LL |     let _y: [u8; _] = [0; 3];
+   |                  ^ help: consider specifying the array length: `3`
+   |
+   = note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
+   = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
+
+error[E0747]: type provided when a constant was expected
+  --> $DIR/feature-gate-generic_arg_infer.rs:20:20
+   |
+LL |     let _x = foo::<_>([1,2]);
+   |                    ^
+   |
+   = help: const arguments cannot yet be inferred with `_`
+   = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
+
+error[E0658]: using `_` for array lengths is unstable
+  --> $DIR/feature-gate-generic_arg_infer.rs:11:27
+   |
+LL |     let _x: [u8; 3] = [0; _];
+   |                           ^
+   |
+   = note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
+   = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0658, E0747.
+For more information about an error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-generic_arg_infer.rs b/tests/ui/feature-gates/feature-gate-generic_arg_infer.rs
new file mode 100644
index 000000000..afd14b784
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-generic_arg_infer.rs
@@ -0,0 +1,23 @@
+// [feature] run-pass
+// revisions: normal feature
+
+#![cfg_attr(feature, feature(generic_arg_infer))]
+
+fn foo<const N: usize>(_: [u8; N]) -> [u8; N] {
+  [0; N]
+}
+
+fn bar() {
+    let _x: [u8; 3] = [0; _];
+    //[normal]~^ ERROR: using `_` for array lengths is unstable
+    //[normal]~| ERROR: in expressions, `_` can only be used on the left-hand side of an assignment
+    let _y: [u8; _] = [0; 3];
+    //[normal]~^ ERROR: using `_` for array lengths is unstable
+    //[normal]~| ERROR: in expressions, `_` can only be used on the left-hand side of an assignment
+}
+
+fn main() {
+    let _x = foo::<_>([1,2]);
+    //[normal]~^ ERROR: type provided when a constant was expected
+    let _y = bar();
+}
diff --git a/tests/ui/feature-gates/feature-gate-generic_associated_types_extended.rs b/tests/ui/feature-gates/feature-gate-generic_associated_types_extended.rs
new file mode 100644
index 000000000..7842d44ac
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-generic_associated_types_extended.rs
@@ -0,0 +1,4 @@
+// This feature doesn't *currently* fire on any specific code; it's just a
+// behavior change. Future changes might.
+#[rustc_error] //~ the
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-generic_associated_types_extended.stderr b/tests/ui/feature-gates/feature-gate-generic_associated_types_extended.stderr
new file mode 100644
index 000000000..bb1622628
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-generic_associated_types_extended.stderr
@@ -0,0 +1,11 @@
+error[E0658]: the `#[rustc_error]` attribute is just used for rustc unit tests and will never be stable
+  --> $DIR/feature-gate-generic_associated_types_extended.rs:3:1
+   |
+LL | #[rustc_error]
+   | ^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.rs b/tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.rs
new file mode 100644
index 000000000..0db8088f7
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.rs
@@ -0,0 +1,6 @@
+fn f() -> impl Fn() -> impl Sized { || () }
+//~^ ERROR `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
+fn g() -> &'static dyn Fn() -> impl Sized { &|| () }
+//~^ ERROR `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr b/tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr
new file mode 100644
index 000000000..760dcb615
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr
@@ -0,0 +1,21 @@
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
+  --> $DIR/feature-gate-impl_trait_in_fn_trait_return.rs:1:24
+   |
+LL | fn f() -> impl Fn() -> impl Sized { || () }
+   |                        ^^^^^^^^^^
+   |
+   = note: see issue #99697 <https://github.com/rust-lang/rust/issues/99697> for more information
+   = help: add `#![feature(impl_trait_in_fn_trait_return)]` to the crate attributes to enable
+
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
+  --> $DIR/feature-gate-impl_trait_in_fn_trait_return.rs:3:32
+   |
+LL | fn g() -> &'static dyn Fn() -> impl Sized { &|| () }
+   |                                ^^^^^^^^^^
+   |
+   = note: see issue #99697 <https://github.com/rust-lang/rust/issues/99697> for more information
+   = help: add `#![feature(impl_trait_in_fn_trait_return)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0562`.
diff --git a/tests/ui/feature-gates/feature-gate-imported_main.rs b/tests/ui/feature-gates/feature-gate-imported_main.rs
new file mode 100644
index 000000000..b351d0d0e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-imported_main.rs
@@ -0,0 +1,6 @@
+pub mod foo {
+    pub fn bar() {
+        println!("Hello world!");
+    }
+}
+use foo::bar as main; //~ ERROR using an imported function as entry point
diff --git a/tests/ui/feature-gates/feature-gate-imported_main.stderr b/tests/ui/feature-gates/feature-gate-imported_main.stderr
new file mode 100644
index 000000000..3b879fdfc
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-imported_main.stderr
@@ -0,0 +1,12 @@
+error[E0658]: using an imported function as entry point `main` is experimental
+  --> $DIR/feature-gate-imported_main.rs:6:5
+   |
+LL | use foo::bar as main;
+   |     ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #28937 <https://github.com/rust-lang/rust/issues/28937> for more information
+   = help: add `#![feature(imported_main)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-inherent_associated_types.rs b/tests/ui/feature-gates/feature-gate-inherent_associated_types.rs
new file mode 100644
index 000000000..fc7c6dbc0
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-inherent_associated_types.rs
@@ -0,0 +1,10 @@
+// Test that inherent associated types cannot be used when inherent_associated_types
+// feature gate is not used.
+
+struct Foo;
+
+impl Foo {
+    type Bar = isize; //~ERROR inherent associated types are unstable
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-inherent_associated_types.stderr b/tests/ui/feature-gates/feature-gate-inherent_associated_types.stderr
new file mode 100644
index 000000000..76e65d239
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-inherent_associated_types.stderr
@@ -0,0 +1,12 @@
+error[E0658]: inherent associated types are unstable
+  --> $DIR/feature-gate-inherent_associated_types.rs:7:5
+   |
+LL |     type Bar = isize;
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #8995 <https://github.com/rust-lang/rust/issues/8995> for more information
+   = help: add `#![feature(inherent_associated_types)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-inline_const.rs b/tests/ui/feature-gates/feature-gate-inline_const.rs
new file mode 100644
index 000000000..43ff90d23
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-inline_const.rs
@@ -0,0 +1,6 @@
+fn main() {
+    let _ = const {
+        //~^ ERROR inline-const is experimental [E0658]
+        true
+    };
+}
diff --git a/tests/ui/feature-gates/feature-gate-inline_const.stderr b/tests/ui/feature-gates/feature-gate-inline_const.stderr
new file mode 100644
index 000000000..be2f56715
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-inline_const.stderr
@@ -0,0 +1,12 @@
+error[E0658]: inline-const is experimental
+  --> $DIR/feature-gate-inline_const.rs:2:13
+   |
+LL |     let _ = const {
+   |             ^^^^^
+   |
+   = note: see issue #76001 <https://github.com/rust-lang/rust/issues/76001> for more information
+   = help: add `#![feature(inline_const)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-inline_const_pat.rs b/tests/ui/feature-gates/feature-gate-inline_const_pat.rs
new file mode 100644
index 000000000..3d0df289f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-inline_const_pat.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let const { () } = ();
+    //~^ ERROR inline-const in pattern position is experimental [E0658]
+}
diff --git a/tests/ui/feature-gates/feature-gate-inline_const_pat.stderr b/tests/ui/feature-gates/feature-gate-inline_const_pat.stderr
new file mode 100644
index 000000000..ca533d850
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-inline_const_pat.stderr
@@ -0,0 +1,12 @@
+error[E0658]: inline-const in pattern position is experimental
+  --> $DIR/feature-gate-inline_const_pat.rs:2:9
+   |
+LL |     let const { () } = ();
+   |         ^^^^^
+   |
+   = note: see issue #76001 <https://github.com/rust-lang/rust/issues/76001> for more information
+   = help: add `#![feature(inline_const_pat)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-intrinsics.rs b/tests/ui/feature-gates/feature-gate-intrinsics.rs
new file mode 100644
index 000000000..e0dc3cc57
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-intrinsics.rs
@@ -0,0 +1,8 @@
+extern "rust-intrinsic" {   //~ ERROR intrinsics are subject to change
+    fn bar(); //~ ERROR unrecognized intrinsic function: `bar`
+}
+
+extern "rust-intrinsic" fn baz() {} //~ ERROR intrinsics are subject to change
+//~^ ERROR intrinsic must be in
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-intrinsics.stderr b/tests/ui/feature-gates/feature-gate-intrinsics.stderr
new file mode 100644
index 000000000..8f943d357
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-intrinsics.stderr
@@ -0,0 +1,32 @@
+error[E0658]: intrinsics are subject to change
+  --> $DIR/feature-gate-intrinsics.rs:1:8
+   |
+LL | extern "rust-intrinsic" {
+   |        ^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(intrinsics)]` to the crate attributes to enable
+
+error[E0658]: intrinsics are subject to change
+  --> $DIR/feature-gate-intrinsics.rs:5:8
+   |
+LL | extern "rust-intrinsic" fn baz() {}
+   |        ^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(intrinsics)]` to the crate attributes to enable
+
+error[E0093]: unrecognized intrinsic function: `bar`
+  --> $DIR/feature-gate-intrinsics.rs:2:5
+   |
+LL |     fn bar();
+   |     ^^^^^^^^^ unrecognized intrinsic
+
+error: intrinsic must be in `extern "rust-intrinsic" { ... }` block
+  --> $DIR/feature-gate-intrinsics.rs:5:34
+   |
+LL | extern "rust-intrinsic" fn baz() {}
+   |                                  ^^
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0093, E0658.
+For more information about an error, try `rustc --explain E0093`.
diff --git a/tests/ui/feature-gates/feature-gate-is_sorted.rs b/tests/ui/feature-gates/feature-gate-is_sorted.rs
new file mode 100644
index 000000000..359ed835b
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-is_sorted.rs
@@ -0,0 +1,13 @@
+fn main() {
+    // Assert `Iterator` methods are unstable
+    assert!([1, 2, 2, 9].iter().is_sorted());
+    //~^ ERROR: use of unstable library feature 'is_sorted': new API
+    assert!(![-2i32, -1, 0, 3].iter().is_sorted_by_key(|n| n.abs()));
+    //~^ ERROR: use of unstable library feature 'is_sorted': new API
+
+    // Assert `[T]` methods are unstable
+    assert!([1, 2, 2, 9].is_sorted());
+    //~^ ERROR: use of unstable library feature 'is_sorted': new API
+    assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));
+    //~^ ERROR: use of unstable library feature 'is_sorted': new API
+}
diff --git a/tests/ui/feature-gates/feature-gate-is_sorted.stderr b/tests/ui/feature-gates/feature-gate-is_sorted.stderr
new file mode 100644
index 000000000..ccac82707
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-is_sorted.stderr
@@ -0,0 +1,39 @@
+error[E0658]: use of unstable library feature 'is_sorted': new API
+  --> $DIR/feature-gate-is_sorted.rs:3:33
+   |
+LL |     assert!([1, 2, 2, 9].iter().is_sorted());
+   |                                 ^^^^^^^^^
+   |
+   = note: see issue #53485 <https://github.com/rust-lang/rust/issues/53485> for more information
+   = help: add `#![feature(is_sorted)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'is_sorted': new API
+  --> $DIR/feature-gate-is_sorted.rs:5:39
+   |
+LL |     assert!(![-2i32, -1, 0, 3].iter().is_sorted_by_key(|n| n.abs()));
+   |                                       ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #53485 <https://github.com/rust-lang/rust/issues/53485> for more information
+   = help: add `#![feature(is_sorted)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'is_sorted': new API
+  --> $DIR/feature-gate-is_sorted.rs:9:26
+   |
+LL |     assert!([1, 2, 2, 9].is_sorted());
+   |                          ^^^^^^^^^
+   |
+   = note: see issue #53485 <https://github.com/rust-lang/rust/issues/53485> for more information
+   = help: add `#![feature(is_sorted)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'is_sorted': new API
+  --> $DIR/feature-gate-is_sorted.rs:11:32
+   |
+LL |     assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));
+   |                                ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #53485 <https://github.com/rust-lang/rust/issues/53485> for more information
+   = help: add `#![feature(is_sorted)]` to the crate attributes to enable
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-lang-items.rs b/tests/ui/feature-gates/feature-gate-lang-items.rs
new file mode 100644
index 000000000..93262f217
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-lang-items.rs
@@ -0,0 +1,5 @@
+#[lang = "foo"] //~ ERROR language items are subject to change
+                //~^ ERROR definition of an unknown language item: `foo`
+trait Foo {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-lang-items.stderr b/tests/ui/feature-gates/feature-gate-lang-items.stderr
new file mode 100644
index 000000000..c2496863f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-lang-items.stderr
@@ -0,0 +1,18 @@
+error[E0658]: language items are subject to change
+  --> $DIR/feature-gate-lang-items.rs:1:1
+   |
+LL | #[lang = "foo"]
+   | ^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(lang_items)]` to the crate attributes to enable
+
+error[E0522]: definition of an unknown language item: `foo`
+  --> $DIR/feature-gate-lang-items.rs:1:1
+   |
+LL | #[lang = "foo"]
+   | ^^^^^^^^^^^^^^^ definition of unknown language item `foo`
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0522, E0658.
+For more information about an error, try `rustc --explain E0522`.
diff --git a/tests/ui/feature-gates/feature-gate-large-assignments.rs b/tests/ui/feature-gates/feature-gate-large-assignments.rs
new file mode 100644
index 000000000..7e9e574bf
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-large-assignments.rs
@@ -0,0 +1,5 @@
+// check that `move_size_limit is feature-gated
+
+#![move_size_limit = "42"] //~ ERROR the `#[move_size_limit]` attribute is an experimental feature
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-large-assignments.stderr b/tests/ui/feature-gates/feature-gate-large-assignments.stderr
new file mode 100644
index 000000000..8ddc3043e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-large-assignments.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[move_size_limit]` attribute is an experimental feature
+  --> $DIR/feature-gate-large-assignments.rs:3:1
+   |
+LL | #![move_size_limit = "42"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #83518 <https://github.com/rust-lang/rust/issues/83518> for more information
+   = help: add `#![feature(large_assignments)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-link_cfg.rs b/tests/ui/feature-gates/feature-gate-link_cfg.rs
new file mode 100644
index 000000000..d30ee3bcf
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-link_cfg.rs
@@ -0,0 +1,5 @@
+#[link(name = "foo", cfg(foo))]
+//~^ ERROR: is unstable
+extern "C" {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-link_cfg.stderr b/tests/ui/feature-gates/feature-gate-link_cfg.stderr
new file mode 100644
index 000000000..8f47d5965
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-link_cfg.stderr
@@ -0,0 +1,12 @@
+error[E0658]: link cfg is unstable
+  --> $DIR/feature-gate-link_cfg.rs:1:22
+   |
+LL | #[link(name = "foo", cfg(foo))]
+   |                      ^^^^^^^^
+   |
+   = note: see issue #37406 <https://github.com/rust-lang/rust/issues/37406> for more information
+   = help: add `#![feature(link_cfg)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-link_llvm_intrinsics.rs b/tests/ui/feature-gates/feature-gate-link_llvm_intrinsics.rs
new file mode 100644
index 000000000..7391ea94e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-link_llvm_intrinsics.rs
@@ -0,0 +1,7 @@
+extern "C" {
+    #[link_name = "llvm.sqrt.f32"]
+    fn sqrt(x: f32) -> f32;
+//~^ ERROR linking to LLVM intrinsics is experimental
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-link_llvm_intrinsics.stderr b/tests/ui/feature-gates/feature-gate-link_llvm_intrinsics.stderr
new file mode 100644
index 000000000..6bce5b823
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-link_llvm_intrinsics.stderr
@@ -0,0 +1,12 @@
+error[E0658]: linking to LLVM intrinsics is experimental
+  --> $DIR/feature-gate-link_llvm_intrinsics.rs:3:5
+   |
+LL |     fn sqrt(x: f32) -> f32;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #29602 <https://github.com/rust-lang/rust/issues/29602> for more information
+   = help: add `#![feature(link_llvm_intrinsics)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-linkage.rs b/tests/ui/feature-gates/feature-gate-linkage.rs
new file mode 100644
index 000000000..505f31ec6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-linkage.rs
@@ -0,0 +1,6 @@
+extern "C" {
+    #[linkage = "extern_weak"] static foo: *mut isize;
+    //~^ ERROR: the `linkage` attribute is experimental and not portable
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-linkage.stderr b/tests/ui/feature-gates/feature-gate-linkage.stderr
new file mode 100644
index 000000000..a1c73e555
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-linkage.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `linkage` attribute is experimental and not portable across platforms
+  --> $DIR/feature-gate-linkage.rs:2:5
+   |
+LL |     #[linkage = "extern_weak"] static foo: *mut isize;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #29603 <https://github.com/rust-lang/rust/issues/29603> for more information
+   = help: add `#![feature(linkage)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-lint-reasons.rs b/tests/ui/feature-gates/feature-gate-lint-reasons.rs
new file mode 100644
index 000000000..7756074e2
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-lint-reasons.rs
@@ -0,0 +1,5 @@
+#![warn(nonstandard_style, reason = "the standard should be respected")]
+//~^ ERROR lint reasons are experimental
+//~| ERROR lint reasons are experimental
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-lint-reasons.stderr b/tests/ui/feature-gates/feature-gate-lint-reasons.stderr
new file mode 100644
index 000000000..12793c7a2
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-lint-reasons.stderr
@@ -0,0 +1,21 @@
+error[E0658]: lint reasons are experimental
+  --> $DIR/feature-gate-lint-reasons.rs:1:28
+   |
+LL | #![warn(nonstandard_style, reason = "the standard should be respected")]
+   |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #54503 <https://github.com/rust-lang/rust/issues/54503> for more information
+   = help: add `#![feature(lint_reasons)]` to the crate attributes to enable
+
+error[E0658]: lint reasons are experimental
+  --> $DIR/feature-gate-lint-reasons.rs:1:28
+   |
+LL | #![warn(nonstandard_style, reason = "the standard should be respected")]
+   |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #54503 <https://github.com/rust-lang/rust/issues/54503> for more information
+   = help: add `#![feature(lint_reasons)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-log_syntax.rs b/tests/ui/feature-gates/feature-gate-log_syntax.rs
new file mode 100644
index 000000000..181f66cb0
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-log_syntax.rs
@@ -0,0 +1,3 @@
+fn main() {
+    log_syntax!() //~ ERROR `log_syntax!` is not stable enough
+}
diff --git a/tests/ui/feature-gates/feature-gate-log_syntax.stderr b/tests/ui/feature-gates/feature-gate-log_syntax.stderr
new file mode 100644
index 000000000..fdc1c8553
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-log_syntax.stderr
@@ -0,0 +1,12 @@
+error[E0658]: use of unstable library feature 'log_syntax': `log_syntax!` is not stable enough for use and is subject to change
+  --> $DIR/feature-gate-log_syntax.rs:2:5
+   |
+LL |     log_syntax!()
+   |     ^^^^^^^^^^
+   |
+   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
+   = help: add `#![feature(log_syntax)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-log_syntax.stdout b/tests/ui/feature-gates/feature-gate-log_syntax.stdout
new file mode 100644
index 000000000..8b1378917
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-log_syntax.stdout
@@ -0,0 +1 @@
+
diff --git a/tests/ui/feature-gates/feature-gate-log_syntax2.rs b/tests/ui/feature-gates/feature-gate-log_syntax2.rs
new file mode 100644
index 000000000..db1a96f1f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-log_syntax2.rs
@@ -0,0 +1,3 @@
+fn main() {
+    println!("{:?}", log_syntax!()); //~ ERROR `log_syntax!` is not stable
+}
diff --git a/tests/ui/feature-gates/feature-gate-log_syntax2.stderr b/tests/ui/feature-gates/feature-gate-log_syntax2.stderr
new file mode 100644
index 000000000..6deb4a46c
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-log_syntax2.stderr
@@ -0,0 +1,12 @@
+error[E0658]: use of unstable library feature 'log_syntax': `log_syntax!` is not stable enough for use and is subject to change
+  --> $DIR/feature-gate-log_syntax2.rs:2:22
+   |
+LL |     println!("{:?}", log_syntax!());
+   |                      ^^^^^^^^^^
+   |
+   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
+   = help: add `#![feature(log_syntax)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-log_syntax2.stdout b/tests/ui/feature-gates/feature-gate-log_syntax2.stdout
new file mode 100644
index 000000000..8b1378917
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-log_syntax2.stdout
@@ -0,0 +1 @@
+
diff --git a/tests/ui/feature-gates/feature-gate-marker_trait_attr.rs b/tests/ui/feature-gates/feature-gate-marker_trait_attr.rs
new file mode 100644
index 000000000..5050c4792
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-marker_trait_attr.rs
@@ -0,0 +1,9 @@
+use std::fmt::{Debug, Display};
+
+#[marker] trait ExplicitMarker {}
+//~^ ERROR the `#[marker]` attribute is an experimental feature
+
+impl<T: Display> ExplicitMarker for T {}
+impl<T: Debug> ExplicitMarker for T {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-marker_trait_attr.stderr b/tests/ui/feature-gates/feature-gate-marker_trait_attr.stderr
new file mode 100644
index 000000000..e3c3756fd
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-marker_trait_attr.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[marker]` attribute is an experimental feature
+  --> $DIR/feature-gate-marker_trait_attr.rs:3:1
+   |
+LL | #[marker] trait ExplicitMarker {}
+   | ^^^^^^^^^
+   |
+   = note: see issue #29864 <https://github.com/rust-lang/rust/issues/29864> for more information
+   = help: add `#![feature(marker_trait_attr)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-may-dangle.rs b/tests/ui/feature-gates/feature-gate-may-dangle.rs
new file mode 100644
index 000000000..23db92c15
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-may-dangle.rs
@@ -0,0 +1,11 @@
+// gate-test-dropck_eyepatch
+
+// Check that `may_dangle` is rejected if `dropck_eyepatch` feature gate is absent.
+
+struct Pt<A>(A);
+unsafe impl<#[may_dangle] A> Drop for Pt<A> {
+    //~^ ERROR `may_dangle` has unstable semantics and may be removed in the future
+    fn drop(&mut self) { }
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-may-dangle.stderr b/tests/ui/feature-gates/feature-gate-may-dangle.stderr
new file mode 100644
index 000000000..d47a76a50
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-may-dangle.stderr
@@ -0,0 +1,12 @@
+error[E0658]: `may_dangle` has unstable semantics and may be removed in the future
+  --> $DIR/feature-gate-may-dangle.rs:6:13
+   |
+LL | unsafe impl<#[may_dangle] A> Drop for Pt<A> {
+   |             ^^^^^^^^^^^^^
+   |
+   = note: see issue #34761 <https://github.com/rust-lang/rust/issues/34761> for more information
+   = help: add `#![feature(dropck_eyepatch)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-min_const_fn.rs b/tests/ui/feature-gates/feature-gate-min_const_fn.rs
new file mode 100644
index 000000000..8f9b43300
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-min_const_fn.rs
@@ -0,0 +1,35 @@
+// Test use of min_const_fn without feature gate.
+
+const fn foo() -> usize { 0 } // stabilized
+
+trait Foo {
+    const fn foo() -> u32; //~ ERROR functions in traits cannot be declared const
+    const fn bar() -> u32 { 0 } //~ ERROR functions in traits cannot be declared const
+}
+
+impl Foo for u32 {
+    const fn foo() -> u32 { 0 } //~ ERROR functions in traits cannot be declared const
+}
+
+trait Bar {}
+
+impl dyn Bar {
+    const fn baz() -> u32 { 0 } // stabilized
+}
+
+static FOO: usize = foo();
+const BAR: usize = foo();
+
+macro_rules! constant {
+    ($n:ident: $t:ty = $v:expr) => {
+        const $n: $t = $v;
+    }
+}
+
+constant! {
+    BAZ: usize = foo()
+}
+
+fn main() {
+    let x: [usize; foo()] = [];
+}
diff --git a/tests/ui/feature-gates/feature-gate-min_const_fn.stderr b/tests/ui/feature-gates/feature-gate-min_const_fn.stderr
new file mode 100644
index 000000000..d7a585913
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-min_const_fn.stderr
@@ -0,0 +1,21 @@
+error[E0379]: functions in traits cannot be declared const
+  --> $DIR/feature-gate-min_const_fn.rs:6:5
+   |
+LL |     const fn foo() -> u32;
+   |     ^^^^^ functions in traits cannot be const
+
+error[E0379]: functions in traits cannot be declared const
+  --> $DIR/feature-gate-min_const_fn.rs:7:5
+   |
+LL |     const fn bar() -> u32 { 0 }
+   |     ^^^^^ functions in traits cannot be const
+
+error[E0379]: functions in traits cannot be declared const
+  --> $DIR/feature-gate-min_const_fn.rs:11:5
+   |
+LL |     const fn foo() -> u32 { 0 }
+   |     ^^^^^ functions in traits cannot be const
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0379`.
diff --git a/tests/ui/feature-gates/feature-gate-more-qualified-paths.rs b/tests/ui/feature-gates/feature-gate-more-qualified-paths.rs
new file mode 100644
index 000000000..2e05acbfa
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-more-qualified-paths.rs
@@ -0,0 +1,27 @@
+fn main() {
+    // destructure through a qualified path
+    let <Foo as A>::Assoc { br } = StructStruct { br: 2 };
+    //~^ ERROR usage of qualified paths in this context is experimental
+    let _ = <Foo as A>::Assoc { br: 2 };
+    //~^ ERROR usage of qualified paths in this context is experimental
+    let <E>::V(..) = E::V(0);
+    //~^ ERROR usage of qualified paths in this context is experimental
+}
+
+struct StructStruct {
+    br: i8,
+}
+
+struct Foo;
+
+trait A {
+    type Assoc;
+}
+
+impl A for Foo {
+    type Assoc = StructStruct;
+}
+
+enum E {
+    V(u8)
+}
diff --git a/tests/ui/feature-gates/feature-gate-more-qualified-paths.stderr b/tests/ui/feature-gates/feature-gate-more-qualified-paths.stderr
new file mode 100644
index 000000000..80ebcabcf
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-more-qualified-paths.stderr
@@ -0,0 +1,30 @@
+error[E0658]: usage of qualified paths in this context is experimental
+  --> $DIR/feature-gate-more-qualified-paths.rs:3:9
+   |
+LL |     let <Foo as A>::Assoc { br } = StructStruct { br: 2 };
+   |         ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #86935 <https://github.com/rust-lang/rust/issues/86935> for more information
+   = help: add `#![feature(more_qualified_paths)]` to the crate attributes to enable
+
+error[E0658]: usage of qualified paths in this context is experimental
+  --> $DIR/feature-gate-more-qualified-paths.rs:5:13
+   |
+LL |     let _ = <Foo as A>::Assoc { br: 2 };
+   |             ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #86935 <https://github.com/rust-lang/rust/issues/86935> for more information
+   = help: add `#![feature(more_qualified_paths)]` to the crate attributes to enable
+
+error[E0658]: usage of qualified paths in this context is experimental
+  --> $DIR/feature-gate-more-qualified-paths.rs:7:9
+   |
+LL |     let <E>::V(..) = E::V(0);
+   |         ^^^^^^
+   |
+   = note: see issue #86935 <https://github.com/rust-lang/rust/issues/86935> for more information
+   = help: add `#![feature(more_qualified_paths)]` to the crate attributes to enable
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-naked_functions.rs b/tests/ui/feature-gates/feature-gate-naked_functions.rs
new file mode 100644
index 000000000..8e93b1941
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-naked_functions.rs
@@ -0,0 +1,17 @@
+// needs-asm-support
+
+use std::arch::asm;
+
+#[naked]
+//~^ the `#[naked]` attribute is an experimental feature
+extern "C" fn naked() {
+    asm!("", options(noreturn))
+}
+
+#[naked]
+//~^ the `#[naked]` attribute is an experimental feature
+extern "C" fn naked_2() -> isize {
+    asm!("", options(noreturn))
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-naked_functions.stderr b/tests/ui/feature-gates/feature-gate-naked_functions.stderr
new file mode 100644
index 000000000..4378fb363
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-naked_functions.stderr
@@ -0,0 +1,21 @@
+error[E0658]: the `#[naked]` attribute is an experimental feature
+  --> $DIR/feature-gate-naked_functions.rs:5:1
+   |
+LL | #[naked]
+   | ^^^^^^^^
+   |
+   = note: see issue #32408 <https://github.com/rust-lang/rust/issues/32408> for more information
+   = help: add `#![feature(naked_functions)]` to the crate attributes to enable
+
+error[E0658]: the `#[naked]` attribute is an experimental feature
+  --> $DIR/feature-gate-naked_functions.rs:11:1
+   |
+LL | #[naked]
+   | ^^^^^^^^
+   |
+   = note: see issue #32408 <https://github.com/rust-lang/rust/issues/32408> for more information
+   = help: add `#![feature(naked_functions)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-native_link_modifiers_as_needed.rs b/tests/ui/feature-gates/feature-gate-native_link_modifiers_as_needed.rs
new file mode 100644
index 000000000..132bc6ab0
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-native_link_modifiers_as_needed.rs
@@ -0,0 +1,5 @@
+#[link(name = "foo", kind = "dylib", modifiers = "+as-needed")]
+//~^ ERROR: linking modifier `as-needed` is unstable
+extern "C" {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-native_link_modifiers_as_needed.stderr b/tests/ui/feature-gates/feature-gate-native_link_modifiers_as_needed.stderr
new file mode 100644
index 000000000..2ef6a1c04
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-native_link_modifiers_as_needed.stderr
@@ -0,0 +1,12 @@
+error[E0658]: linking modifier `as-needed` is unstable
+  --> $DIR/feature-gate-native_link_modifiers_as_needed.rs:1:50
+   |
+LL | #[link(name = "foo", kind = "dylib", modifiers = "+as-needed")]
+   |                                                  ^^^^^^^^^^^^
+   |
+   = note: see issue #81490 <https://github.com/rust-lang/rust/issues/81490> for more information
+   = help: add `#![feature(native_link_modifiers_as_needed)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-needs-allocator.rs b/tests/ui/feature-gates/feature-gate-needs-allocator.rs
new file mode 100644
index 000000000..08954944b
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-needs-allocator.rs
@@ -0,0 +1,3 @@
+#![needs_allocator] //~ ERROR the `#[needs_allocator]` attribute is
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-needs-allocator.stderr b/tests/ui/feature-gates/feature-gate-needs-allocator.stderr
new file mode 100644
index 000000000..2b213aceb
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-needs-allocator.stderr
@@ -0,0 +1,11 @@
+error[E0658]: the `#[needs_allocator]` attribute is an experimental feature
+  --> $DIR/feature-gate-needs-allocator.rs:1:1
+   |
+LL | #![needs_allocator]
+   | ^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(allocator_internals)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-negate-unsigned.rs b/tests/ui/feature-gates/feature-gate-negate-unsigned.rs
new file mode 100644
index 000000000..05e04f3e2
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-negate-unsigned.rs
@@ -0,0 +1,18 @@
+// Test that negating unsigned integers doesn't compile
+
+struct S;
+impl std::ops::Neg for S {
+    type Output = u32;
+    fn neg(self) -> u32 { 0 }
+}
+
+fn main() {
+    let _max: usize = -1;
+    //~^ ERROR cannot apply unary operator `-` to type `usize`
+
+    let x = 5u8;
+    let _y = -x;
+    //~^ ERROR cannot apply unary operator `-` to type `u8`
+
+    -S; // should not trigger the gate; issue 26840
+}
diff --git a/tests/ui/feature-gates/feature-gate-negate-unsigned.stderr b/tests/ui/feature-gates/feature-gate-negate-unsigned.stderr
new file mode 100644
index 000000000..d1f4ed5cb
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-negate-unsigned.stderr
@@ -0,0 +1,22 @@
+error[E0600]: cannot apply unary operator `-` to type `usize`
+  --> $DIR/feature-gate-negate-unsigned.rs:10:23
+   |
+LL |     let _max: usize = -1;
+   |                       ^^
+   |                       |
+   |                       cannot apply unary operator `-`
+   |                       help: you may have meant the maximum value of `usize`: `usize::MAX`
+   |
+   = note: unsigned values cannot be negated
+
+error[E0600]: cannot apply unary operator `-` to type `u8`
+  --> $DIR/feature-gate-negate-unsigned.rs:14:14
+   |
+LL |     let _y = -x;
+   |              ^^ cannot apply unary operator `-`
+   |
+   = note: unsigned values cannot be negated
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0600`.
diff --git a/tests/ui/feature-gates/feature-gate-never_type.rs b/tests/ui/feature-gates/feature-gate-never_type.rs
new file mode 100644
index 000000000..be8c27dbb
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-never_type.rs
@@ -0,0 +1,17 @@
+// Test that ! errors when used in illegal positions with feature(never_type) disabled
+
+trait Foo {
+    type Wub;
+}
+
+type Ma = (u32, !, i32); //~ ERROR type is experimental
+type Meeshka = Vec<!>; //~ ERROR type is experimental
+type Mow = &'static fn(!) -> !; //~ ERROR type is experimental
+type Skwoz = &'static mut !; //~ ERROR type is experimental
+
+impl Foo for Meeshka {
+    type Wub = !; //~ ERROR type is experimental
+}
+
+fn main() {
+}
diff --git a/tests/ui/feature-gates/feature-gate-never_type.stderr b/tests/ui/feature-gates/feature-gate-never_type.stderr
new file mode 100644
index 000000000..0a59cae9c
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-never_type.stderr
@@ -0,0 +1,48 @@
+error[E0658]: the `!` type is experimental
+  --> $DIR/feature-gate-never_type.rs:7:17
+   |
+LL | type Ma = (u32, !, i32);
+   |                 ^
+   |
+   = note: see issue #35121 <https://github.com/rust-lang/rust/issues/35121> for more information
+   = help: add `#![feature(never_type)]` to the crate attributes to enable
+
+error[E0658]: the `!` type is experimental
+  --> $DIR/feature-gate-never_type.rs:8:20
+   |
+LL | type Meeshka = Vec<!>;
+   |                    ^
+   |
+   = note: see issue #35121 <https://github.com/rust-lang/rust/issues/35121> for more information
+   = help: add `#![feature(never_type)]` to the crate attributes to enable
+
+error[E0658]: the `!` type is experimental
+  --> $DIR/feature-gate-never_type.rs:9:24
+   |
+LL | type Mow = &'static fn(!) -> !;
+   |                        ^
+   |
+   = note: see issue #35121 <https://github.com/rust-lang/rust/issues/35121> for more information
+   = help: add `#![feature(never_type)]` to the crate attributes to enable
+
+error[E0658]: the `!` type is experimental
+  --> $DIR/feature-gate-never_type.rs:10:27
+   |
+LL | type Skwoz = &'static mut !;
+   |                           ^
+   |
+   = note: see issue #35121 <https://github.com/rust-lang/rust/issues/35121> for more information
+   = help: add `#![feature(never_type)]` to the crate attributes to enable
+
+error[E0658]: the `!` type is experimental
+  --> $DIR/feature-gate-never_type.rs:13:16
+   |
+LL |     type Wub = !;
+   |                ^
+   |
+   = note: see issue #35121 <https://github.com/rust-lang/rust/issues/35121> for more information
+   = help: add `#![feature(never_type)]` to the crate attributes to enable
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-no_core.rs b/tests/ui/feature-gates/feature-gate-no_core.rs
new file mode 100644
index 000000000..706efd786
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-no_core.rs
@@ -0,0 +1,5 @@
+#![crate_type = "rlib"]
+
+#![no_core] //~ ERROR the `#[no_core]` attribute is an experimental feature
+
+pub struct S {}
diff --git a/tests/ui/feature-gates/feature-gate-no_core.stderr b/tests/ui/feature-gates/feature-gate-no_core.stderr
new file mode 100644
index 000000000..8430a9ec6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-no_core.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[no_core]` attribute is an experimental feature
+  --> $DIR/feature-gate-no_core.rs:3:1
+   |
+LL | #![no_core]
+   | ^^^^^^^^^^^
+   |
+   = note: see issue #29639 <https://github.com/rust-lang/rust/issues/29639> for more information
+   = help: add `#![feature(no_core)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-no_coverage.rs b/tests/ui/feature-gates/feature-gate-no_coverage.rs
new file mode 100644
index 000000000..fd4c6f760
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-no_coverage.rs
@@ -0,0 +1,13 @@
+#![crate_type = "lib"]
+
+#[derive(PartialEq, Eq)] // ensure deriving `Eq` does not enable `feature(no_coverage)`
+struct Foo {
+    a: u8,
+    b: u32,
+}
+
+#[no_coverage] //~ ERROR the `#[no_coverage]` attribute is an experimental feature
+fn requires_feature_no_coverage() -> bool {
+    let bar = Foo { a: 0, b: 0 };
+    bar == Foo { a: 0, b: 0 }
+}
diff --git a/tests/ui/feature-gates/feature-gate-no_coverage.stderr b/tests/ui/feature-gates/feature-gate-no_coverage.stderr
new file mode 100644
index 000000000..f7167e0b7
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-no_coverage.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[no_coverage]` attribute is an experimental feature
+  --> $DIR/feature-gate-no_coverage.rs:9:1
+   |
+LL | #[no_coverage]
+   | ^^^^^^^^^^^^^^
+   |
+   = note: see issue #84605 <https://github.com/rust-lang/rust/issues/84605> for more information
+   = help: add `#![feature(no_coverage)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-no_sanitize.rs b/tests/ui/feature-gates/feature-gate-no_sanitize.rs
new file mode 100644
index 000000000..66a9263e1
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-no_sanitize.rs
@@ -0,0 +1,4 @@
+#[no_sanitize(address)]
+//~^ the `#[no_sanitize]` attribute is an experimental feature
+fn main() {
+}
diff --git a/tests/ui/feature-gates/feature-gate-no_sanitize.stderr b/tests/ui/feature-gates/feature-gate-no_sanitize.stderr
new file mode 100644
index 000000000..399335700
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-no_sanitize.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[no_sanitize]` attribute is an experimental feature
+  --> $DIR/feature-gate-no_sanitize.rs:1:1
+   |
+LL | #[no_sanitize(address)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #39699 <https://github.com/rust-lang/rust/issues/39699> for more information
+   = help: add `#![feature(no_sanitize)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-non_exhaustive_omitted_patterns_lint.rs b/tests/ui/feature-gates/feature-gate-non_exhaustive_omitted_patterns_lint.rs
new file mode 100644
index 000000000..9b646060a
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-non_exhaustive_omitted_patterns_lint.rs
@@ -0,0 +1,34 @@
+// check-fail
+
+#![deny(non_exhaustive_omitted_patterns)]
+//~^ WARNING unknown lint: `non_exhaustive_omitted_patterns`
+//~| WARNING unknown lint: `non_exhaustive_omitted_patterns`
+#![allow(non_exhaustive_omitted_patterns)]
+//~^ WARNING unknown lint: `non_exhaustive_omitted_patterns`
+//~| WARNING unknown lint: `non_exhaustive_omitted_patterns`
+
+fn main() {
+    enum Foo {
+        A, B, C,
+    }
+
+    #[allow(non_exhaustive_omitted_patterns)]
+    //~^ WARNING unknown lint: `non_exhaustive_omitted_patterns`
+    //~| WARNING unknown lint: `non_exhaustive_omitted_patterns`
+    //~| WARNING unknown lint: `non_exhaustive_omitted_patterns`
+    //~| WARNING unknown lint: `non_exhaustive_omitted_patterns`
+    match Foo::A {
+        Foo::A => {}
+        Foo::B => {}
+    }
+    //~^^^^ ERROR non-exhaustive patterns: `Foo::C` not covered
+
+    match Foo::A {
+        Foo::A => {}
+        Foo::B => {}
+        #[warn(non_exhaustive_omitted_patterns)]
+        _ => {}
+    }
+    //~^^^ WARNING unknown lint: `non_exhaustive_omitted_patterns`
+    //~| WARNING unknown lint: `non_exhaustive_omitted_patterns`
+}
diff --git a/tests/ui/feature-gates/feature-gate-non_exhaustive_omitted_patterns_lint.stderr b/tests/ui/feature-gates/feature-gate-non_exhaustive_omitted_patterns_lint.stderr
new file mode 100644
index 000000000..4d79ce3c6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-non_exhaustive_omitted_patterns_lint.stderr
@@ -0,0 +1,124 @@
+warning: unknown lint: `non_exhaustive_omitted_patterns`
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:3:1
+   |
+LL | #![deny(non_exhaustive_omitted_patterns)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `non_exhaustive_omitted_patterns` lint is unstable
+   = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
+   = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable
+   = note: `#[warn(unknown_lints)]` on by default
+
+warning: unknown lint: `non_exhaustive_omitted_patterns`
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:6:1
+   |
+LL | #![allow(non_exhaustive_omitted_patterns)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `non_exhaustive_omitted_patterns` lint is unstable
+   = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
+   = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable
+
+warning: unknown lint: `non_exhaustive_omitted_patterns`
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:15:5
+   |
+LL |     #[allow(non_exhaustive_omitted_patterns)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `non_exhaustive_omitted_patterns` lint is unstable
+   = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
+   = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable
+
+warning: unknown lint: `non_exhaustive_omitted_patterns`
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:15:5
+   |
+LL |     #[allow(non_exhaustive_omitted_patterns)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `non_exhaustive_omitted_patterns` lint is unstable
+   = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
+   = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable
+
+warning: unknown lint: `non_exhaustive_omitted_patterns`
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:29:9
+   |
+LL |         #[warn(non_exhaustive_omitted_patterns)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `non_exhaustive_omitted_patterns` lint is unstable
+   = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
+   = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable
+
+warning: unknown lint: `non_exhaustive_omitted_patterns`
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:3:1
+   |
+LL | #![deny(non_exhaustive_omitted_patterns)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `non_exhaustive_omitted_patterns` lint is unstable
+   = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
+   = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable
+
+warning: unknown lint: `non_exhaustive_omitted_patterns`
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:6:1
+   |
+LL | #![allow(non_exhaustive_omitted_patterns)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `non_exhaustive_omitted_patterns` lint is unstable
+   = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
+   = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable
+
+warning: unknown lint: `non_exhaustive_omitted_patterns`
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:15:5
+   |
+LL |     #[allow(non_exhaustive_omitted_patterns)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `non_exhaustive_omitted_patterns` lint is unstable
+   = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
+   = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable
+
+warning: unknown lint: `non_exhaustive_omitted_patterns`
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:15:5
+   |
+LL |     #[allow(non_exhaustive_omitted_patterns)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `non_exhaustive_omitted_patterns` lint is unstable
+   = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
+   = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable
+
+warning: unknown lint: `non_exhaustive_omitted_patterns`
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:29:9
+   |
+LL |         #[warn(non_exhaustive_omitted_patterns)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `non_exhaustive_omitted_patterns` lint is unstable
+   = note: see issue #89554 <https://github.com/rust-lang/rust/issues/89554> for more information
+   = help: add `#![feature(non_exhaustive_omitted_patterns_lint)]` to the crate attributes to enable
+
+error[E0004]: non-exhaustive patterns: `Foo::C` not covered
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:20:11
+   |
+LL |     match Foo::A {
+   |           ^^^^^^ pattern `Foo::C` not covered
+   |
+note: `Foo` defined here
+  --> $DIR/feature-gate-non_exhaustive_omitted_patterns_lint.rs:12:15
+   |
+LL |     enum Foo {
+   |          ---
+LL |         A, B, C,
+   |               ^ not covered
+   = note: the matched value is of type `Foo`
+help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
+   |
+LL ~         Foo::B => {}
+LL +         Foo::C => todo!()
+   |
+
+error: aborting due to previous error; 10 warnings emitted
+
+For more information about this error, try `rustc --explain E0004`.
diff --git a/tests/ui/feature-gates/feature-gate-object_safe_for_dispatch.rs b/tests/ui/feature-gates/feature-gate-object_safe_for_dispatch.rs
new file mode 100644
index 000000000..37348e476
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-object_safe_for_dispatch.rs
@@ -0,0 +1,41 @@
+// Test that the use of the non object-safe trait objects
+// are gated by `object_safe_for_dispatch` feature gate.
+
+trait NonObjectSafe1: Sized {}
+
+trait NonObjectSafe2 {
+    fn static_fn() {}
+}
+
+trait NonObjectSafe3 {
+    fn foo<T>(&self);
+}
+
+trait NonObjectSafe4 {
+    fn foo(&self, s: &Self);
+}
+
+fn takes_non_object_safe_ref<T>(obj: &dyn NonObjectSafe1) {
+    //~^ ERROR E0038
+}
+
+fn return_non_object_safe_ref() -> &'static dyn NonObjectSafe2 {
+    //~^ ERROR E0038
+    loop {}
+}
+
+fn takes_non_object_safe_box(obj: Box<dyn NonObjectSafe3>) {
+    //~^ ERROR E0038
+}
+
+fn return_non_object_safe_rc() -> std::rc::Rc<dyn NonObjectSafe4> {
+    //~^ ERROR E0038
+    loop {}
+}
+
+trait Trait {}
+
+impl Trait for dyn NonObjectSafe1 {}
+//~^ ERROR E0038
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-object_safe_for_dispatch.stderr b/tests/ui/feature-gates/feature-gate-object_safe_for_dispatch.stderr
new file mode 100644
index 000000000..d76c697fe
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-object_safe_for_dispatch.stderr
@@ -0,0 +1,83 @@
+error[E0038]: the trait `NonObjectSafe1` cannot be made into an object
+  --> $DIR/feature-gate-object_safe_for_dispatch.rs:18:39
+   |
+LL | fn takes_non_object_safe_ref<T>(obj: &dyn NonObjectSafe1) {
+   |                                       ^^^^^^^^^^^^^^^^^^ `NonObjectSafe1` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/feature-gate-object_safe_for_dispatch.rs:4:23
+   |
+LL | trait NonObjectSafe1: Sized {}
+   |       --------------  ^^^^^ ...because it requires `Self: Sized`
+   |       |
+   |       this trait cannot be made into an object...
+
+error[E0038]: the trait `NonObjectSafe2` cannot be made into an object
+  --> $DIR/feature-gate-object_safe_for_dispatch.rs:22:45
+   |
+LL | fn return_non_object_safe_ref() -> &'static dyn NonObjectSafe2 {
+   |                                             ^^^^^^^^^^^^^^^^^^ `NonObjectSafe2` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/feature-gate-object_safe_for_dispatch.rs:7:8
+   |
+LL | trait NonObjectSafe2 {
+   |       -------------- this trait cannot be made into an object...
+LL |     fn static_fn() {}
+   |        ^^^^^^^^^ ...because associated function `static_fn` has no `self` parameter
+help: consider turning `static_fn` into a method by giving it a `&self` argument
+   |
+LL |     fn static_fn(&self) {}
+   |                  +++++
+help: alternatively, consider constraining `static_fn` so it does not apply to trait objects
+   |
+LL |     fn static_fn() where Self: Sized {}
+   |                    +++++++++++++++++
+
+error[E0038]: the trait `NonObjectSafe3` cannot be made into an object
+  --> $DIR/feature-gate-object_safe_for_dispatch.rs:27:39
+   |
+LL | fn takes_non_object_safe_box(obj: Box<dyn NonObjectSafe3>) {
+   |                                       ^^^^^^^^^^^^^^^^^^ `NonObjectSafe3` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/feature-gate-object_safe_for_dispatch.rs:11:8
+   |
+LL | trait NonObjectSafe3 {
+   |       -------------- this trait cannot be made into an object...
+LL |     fn foo<T>(&self);
+   |        ^^^ ...because method `foo` has generic type parameters
+   = help: consider moving `foo` to another trait
+
+error[E0038]: the trait `NonObjectSafe4` cannot be made into an object
+  --> $DIR/feature-gate-object_safe_for_dispatch.rs:31:47
+   |
+LL | fn return_non_object_safe_rc() -> std::rc::Rc<dyn NonObjectSafe4> {
+   |                                               ^^^^^^^^^^^^^^^^^^ `NonObjectSafe4` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/feature-gate-object_safe_for_dispatch.rs:15:22
+   |
+LL | trait NonObjectSafe4 {
+   |       -------------- this trait cannot be made into an object...
+LL |     fn foo(&self, s: &Self);
+   |                      ^^^^^ ...because method `foo` references the `Self` type in this parameter
+   = help: consider moving `foo` to another trait
+
+error[E0038]: the trait `NonObjectSafe1` cannot be made into an object
+  --> $DIR/feature-gate-object_safe_for_dispatch.rs:38:16
+   |
+LL | impl Trait for dyn NonObjectSafe1 {}
+   |                ^^^^^^^^^^^^^^^^^^ `NonObjectSafe1` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/feature-gate-object_safe_for_dispatch.rs:4:23
+   |
+LL | trait NonObjectSafe1: Sized {}
+   |       --------------  ^^^^^ ...because it requires `Self: Sized`
+   |       |
+   |       this trait cannot be made into an object...
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/feature-gates/feature-gate-omit-gdb-pretty-printer-section.rs b/tests/ui/feature-gates/feature-gate-omit-gdb-pretty-printer-section.rs
new file mode 100644
index 000000000..66bf79738
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-omit-gdb-pretty-printer-section.rs
@@ -0,0 +1,2 @@
+#[omit_gdb_pretty_printer_section] //~ ERROR the `#[omit_gdb_pretty_printer_section]` attribute is
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-omit-gdb-pretty-printer-section.stderr b/tests/ui/feature-gates/feature-gate-omit-gdb-pretty-printer-section.stderr
new file mode 100644
index 000000000..a5ec3599f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-omit-gdb-pretty-printer-section.stderr
@@ -0,0 +1,11 @@
+error[E0658]: the `#[omit_gdb_pretty_printer_section]` attribute is just used for the Rust test suite
+  --> $DIR/feature-gate-omit-gdb-pretty-printer-section.rs:1:1
+   |
+LL | #[omit_gdb_pretty_printer_section]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(omit_gdb_pretty_printer_section)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-optimize_attribute.rs b/tests/ui/feature-gates/feature-gate-optimize_attribute.rs
new file mode 100644
index 000000000..15aa3a6af
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-optimize_attribute.rs
@@ -0,0 +1,18 @@
+#![crate_type="rlib"]
+#![optimize(speed)] //~ ERROR the `#[optimize]` attribute is an experimental feature
+
+#[optimize(size)] //~ ERROR the `#[optimize]` attribute is an experimental feature
+mod module {
+
+#[optimize(size)] //~ ERROR the `#[optimize]` attribute is an experimental feature
+fn size() {}
+
+#[optimize(speed)] //~ ERROR the `#[optimize]` attribute is an experimental feature
+fn speed() {}
+
+#[optimize(banana)]
+//~^ ERROR the `#[optimize]` attribute is an experimental feature
+//~| ERROR E0722
+fn not_known() {}
+
+}
diff --git a/tests/ui/feature-gates/feature-gate-optimize_attribute.stderr b/tests/ui/feature-gates/feature-gate-optimize_attribute.stderr
new file mode 100644
index 000000000..a3ced3515
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-optimize_attribute.stderr
@@ -0,0 +1,55 @@
+error[E0658]: the `#[optimize]` attribute is an experimental feature
+  --> $DIR/feature-gate-optimize_attribute.rs:7:1
+   |
+LL | #[optimize(size)]
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
+   = help: add `#![feature(optimize_attribute)]` to the crate attributes to enable
+
+error[E0658]: the `#[optimize]` attribute is an experimental feature
+  --> $DIR/feature-gate-optimize_attribute.rs:10:1
+   |
+LL | #[optimize(speed)]
+   | ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
+   = help: add `#![feature(optimize_attribute)]` to the crate attributes to enable
+
+error[E0658]: the `#[optimize]` attribute is an experimental feature
+  --> $DIR/feature-gate-optimize_attribute.rs:13:1
+   |
+LL | #[optimize(banana)]
+   | ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
+   = help: add `#![feature(optimize_attribute)]` to the crate attributes to enable
+
+error[E0658]: the `#[optimize]` attribute is an experimental feature
+  --> $DIR/feature-gate-optimize_attribute.rs:4:1
+   |
+LL | #[optimize(size)]
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
+   = help: add `#![feature(optimize_attribute)]` to the crate attributes to enable
+
+error[E0658]: the `#[optimize]` attribute is an experimental feature
+  --> $DIR/feature-gate-optimize_attribute.rs:2:1
+   |
+LL | #![optimize(speed)]
+   | ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #54882 <https://github.com/rust-lang/rust/issues/54882> for more information
+   = help: add `#![feature(optimize_attribute)]` to the crate attributes to enable
+
+error[E0722]: invalid argument
+  --> $DIR/feature-gate-optimize_attribute.rs:13:12
+   |
+LL | #[optimize(banana)]
+   |            ^^^^^^
+
+error: aborting due to 6 previous errors
+
+Some errors have detailed explanations: E0658, E0722.
+For more information about an error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-overlapping_marker_traits.rs b/tests/ui/feature-gates/feature-gate-overlapping_marker_traits.rs
new file mode 100644
index 000000000..6922d6f83
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-overlapping_marker_traits.rs
@@ -0,0 +1,9 @@
+use std::fmt::{Debug, Display};
+
+trait MyMarker {}
+
+impl<T: Display> MyMarker for T {}
+impl<T: Debug> MyMarker for T {}
+//~^ ERROR E0119
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-overlapping_marker_traits.stderr b/tests/ui/feature-gates/feature-gate-overlapping_marker_traits.stderr
new file mode 100644
index 000000000..0526c6dc8
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-overlapping_marker_traits.stderr
@@ -0,0 +1,11 @@
+error[E0119]: conflicting implementations of trait `MyMarker`
+  --> $DIR/feature-gate-overlapping_marker_traits.rs:6:1
+   |
+LL | impl<T: Display> MyMarker for T {}
+   | ------------------------------- first implementation here
+LL | impl<T: Debug> MyMarker for T {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0119`.
diff --git a/tests/ui/feature-gates/feature-gate-precise_pointer_size_matching.rs b/tests/ui/feature-gates/feature-gate-precise_pointer_size_matching.rs
new file mode 100644
index 000000000..4c77180b7
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-precise_pointer_size_matching.rs
@@ -0,0 +1,17 @@
+fn main() {
+    match 0usize {
+        //~^ ERROR non-exhaustive patterns: `_` not covered
+        //~| NOTE pattern `_` not covered
+        //~| NOTE the matched value is of type `usize`
+        //~| NOTE `usize` does not have a fixed maximum value
+        0..=usize::MAX => {}
+    }
+
+    match 0isize {
+        //~^ ERROR non-exhaustive patterns: `_` not covered
+        //~| NOTE pattern `_` not covered
+        //~| NOTE the matched value is of type `isize`
+        //~| NOTE `isize` does not have a fixed maximum value
+        isize::MIN..=isize::MAX => {}
+    }
+}
diff --git a/tests/ui/feature-gates/feature-gate-precise_pointer_size_matching.stderr b/tests/ui/feature-gates/feature-gate-precise_pointer_size_matching.stderr
new file mode 100644
index 000000000..b55106833
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-precise_pointer_size_matching.stderr
@@ -0,0 +1,33 @@
+error[E0004]: non-exhaustive patterns: `_` not covered
+  --> $DIR/feature-gate-precise_pointer_size_matching.rs:2:11
+   |
+LL |     match 0usize {
+   |           ^^^^^^ pattern `_` not covered
+   |
+   = note: the matched value is of type `usize`
+   = note: `usize` does not have a fixed maximum value, so a wildcard `_` is necessary to match exhaustively
+   = help: add `#![feature(precise_pointer_size_matching)]` to the crate attributes to enable precise `usize` matching
+help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
+   |
+LL ~         0..=usize::MAX => {}
+LL +         _ => todo!()
+   |
+
+error[E0004]: non-exhaustive patterns: `_` not covered
+  --> $DIR/feature-gate-precise_pointer_size_matching.rs:10:11
+   |
+LL |     match 0isize {
+   |           ^^^^^^ pattern `_` not covered
+   |
+   = note: the matched value is of type `isize`
+   = note: `isize` does not have a fixed maximum value, so a wildcard `_` is necessary to match exhaustively
+   = help: add `#![feature(precise_pointer_size_matching)]` to the crate attributes to enable precise `isize` matching
+help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
+   |
+LL ~         isize::MIN..=isize::MAX => {}
+LL +         _ => todo!()
+   |
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0004`.
diff --git a/tests/ui/feature-gates/feature-gate-prelude_import.rs b/tests/ui/feature-gates/feature-gate-prelude_import.rs
new file mode 100644
index 000000000..a338bf973
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-prelude_import.rs
@@ -0,0 +1,4 @@
+#[prelude_import] //~ ERROR `#[prelude_import]` is for use by rustc only
+use std::prelude::v1::*;
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-prelude_import.stderr b/tests/ui/feature-gates/feature-gate-prelude_import.stderr
new file mode 100644
index 000000000..8686aed8f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-prelude_import.stderr
@@ -0,0 +1,11 @@
+error[E0658]: `#[prelude_import]` is for use by rustc only
+  --> $DIR/feature-gate-prelude_import.rs:1:1
+   |
+LL | #[prelude_import]
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(prelude_import)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-profiler-runtime.rs b/tests/ui/feature-gates/feature-gate-profiler-runtime.rs
new file mode 100644
index 000000000..f8a709634
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-profiler-runtime.rs
@@ -0,0 +1,3 @@
+#![profiler_runtime] //~ ERROR the `#[profiler_runtime]` attribute is
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-profiler-runtime.stderr b/tests/ui/feature-gates/feature-gate-profiler-runtime.stderr
new file mode 100644
index 000000000..18e6503c5
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-profiler-runtime.stderr
@@ -0,0 +1,11 @@
+error[E0658]: the `#[profiler_runtime]` attribute is used to identify the `profiler_builtins` crate which contains the profiler runtime and will never be stable
+  --> $DIR/feature-gate-profiler-runtime.rs:1:1
+   |
+LL | #![profiler_runtime]
+   | ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(profiler_runtime)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-public_private_dependencies.rs b/tests/ui/feature-gates/feature-gate-public_private_dependencies.rs
new file mode 100644
index 000000000..b8fb4b8dc
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-public_private_dependencies.rs
@@ -0,0 +1,20 @@
+// This test is different from other feature gate tests.
+// Instead of checking that an error occurs without the feature gate,
+// it checks that *no* errors/warnings occurs without the feature gate.
+// This is due to the fact that 'public_private_dependencies' just enables
+// a lint, so disabling it shouldn't cause any code to stop compiling.
+
+// run-pass
+// aux-build:pub_dep.rs
+
+// Without ![feature(public_private_dependencies)],
+// this should do nothing/
+#![deny(exported_private_dependencies)]
+
+extern crate pub_dep;
+
+pub struct Foo {
+    pub field: pub_dep::PubType
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-raw-dylib-2.rs b/tests/ui/feature-gates/feature-gate-raw-dylib-2.rs
new file mode 100644
index 000000000..fc47a9061
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-raw-dylib-2.rs
@@ -0,0 +1,12 @@
+// only-x86
+#[link(name = "foo")]
+extern "C" {
+    #[link_ordinal(42)]
+    //~^ ERROR: `#[link_ordinal]` is unstable on x86
+    fn foo();
+    #[link_ordinal(5)]
+    //~^ ERROR: `#[link_ordinal]` is unstable on x86
+    static mut imported_variable: i32;
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-raw-dylib-2.stderr b/tests/ui/feature-gates/feature-gate-raw-dylib-2.stderr
new file mode 100644
index 000000000..0e900760d
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-raw-dylib-2.stderr
@@ -0,0 +1,21 @@
+error[E0658]: `#[link_ordinal]` is unstable on x86
+  --> $DIR/feature-gate-raw-dylib-2.rs:4:5
+   |
+LL |     #[link_ordinal(42)]
+   |     ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #58713 <https://github.com/rust-lang/rust/issues/58713> for more information
+   = help: add `#![feature(raw_dylib)]` to the crate attributes to enable
+
+error[E0658]: `#[link_ordinal]` is unstable on x86
+  --> $DIR/feature-gate-raw-dylib-2.rs:7:5
+   |
+LL |     #[link_ordinal(5)]
+   |     ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #58713 <https://github.com/rust-lang/rust/issues/58713> for more information
+   = help: add `#![feature(raw_dylib)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-raw-dylib-import-name-type.rs b/tests/ui/feature-gates/feature-gate-raw-dylib-import-name-type.rs
new file mode 100644
index 000000000..295f502d6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-raw-dylib-import-name-type.rs
@@ -0,0 +1,8 @@
+// only-windows
+// only-x86
+#[link(name = "foo", kind = "raw-dylib", import_name_type = "decorated")]
+//~^ ERROR link kind `raw-dylib` is unstable on x86
+//~| ERROR import name type is unstable
+extern "C" {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-raw-dylib-import-name-type.stderr b/tests/ui/feature-gates/feature-gate-raw-dylib-import-name-type.stderr
new file mode 100644
index 000000000..d6b165b76
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-raw-dylib-import-name-type.stderr
@@ -0,0 +1,21 @@
+error[E0658]: link kind `raw-dylib` is unstable on x86
+  --> $DIR/feature-gate-raw-dylib-import-name-type.rs:3:29
+   |
+LL | #[link(name = "foo", kind = "raw-dylib", import_name_type = "decorated")]
+   |                             ^^^^^^^^^^^
+   |
+   = note: see issue #58713 <https://github.com/rust-lang/rust/issues/58713> for more information
+   = help: add `#![feature(raw_dylib)]` to the crate attributes to enable
+
+error[E0658]: import name type is unstable
+  --> $DIR/feature-gate-raw-dylib-import-name-type.rs:3:61
+   |
+LL | #[link(name = "foo", kind = "raw-dylib", import_name_type = "decorated")]
+   |                                                             ^^^^^^^^^^^
+   |
+   = note: see issue #58713 <https://github.com/rust-lang/rust/issues/58713> for more information
+   = help: add `#![feature(raw_dylib)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-raw-dylib.rs b/tests/ui/feature-gates/feature-gate-raw-dylib.rs
new file mode 100644
index 000000000..291cca8fd
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-raw-dylib.rs
@@ -0,0 +1,7 @@
+// only-windows
+// only-x86
+#[link(name = "foo", kind = "raw-dylib")]
+//~^ ERROR: link kind `raw-dylib` is unstable on x86
+extern "C" {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-raw-dylib.stderr b/tests/ui/feature-gates/feature-gate-raw-dylib.stderr
new file mode 100644
index 000000000..f02241e49
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-raw-dylib.stderr
@@ -0,0 +1,12 @@
+error[E0658]: link kind `raw-dylib` is unstable on x86
+  --> $DIR/feature-gate-raw-dylib.rs:3:29
+   |
+LL | #[link(name = "foo", kind = "raw-dylib")]
+   |                             ^^^^^^^^^^^
+   |
+   = note: see issue #58713 <https://github.com/rust-lang/rust/issues/58713> for more information
+   = help: add `#![feature(raw_dylib)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-register_tool.rs b/tests/ui/feature-gates/feature-gate-register_tool.rs
new file mode 100644
index 000000000..e59959328
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-register_tool.rs
@@ -0,0 +1,3 @@
+#![register_tool(tool)] //~ ERROR the `#[register_tool]` attribute is an experimental feature
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-register_tool.stderr b/tests/ui/feature-gates/feature-gate-register_tool.stderr
new file mode 100644
index 000000000..9ffaaa8de
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-register_tool.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[register_tool]` attribute is an experimental feature
+  --> $DIR/feature-gate-register_tool.rs:1:1
+   |
+LL | #![register_tool(tool)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #66079 <https://github.com/rust-lang/rust/issues/66079> for more information
+   = help: add `#![feature(register_tool)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-repr-simd.rs b/tests/ui/feature-gates/feature-gate-repr-simd.rs
new file mode 100644
index 000000000..c527404f5
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-repr-simd.rs
@@ -0,0 +1,9 @@
+#[repr(simd)] //~ error: SIMD types are experimental
+struct Foo(u64, u64);
+
+#[repr(C)] //~ ERROR conflicting representation hints
+//~^ WARN this was previously accepted
+#[repr(simd)] //~ error: SIMD types are experimental
+struct Bar(u64, u64);
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-repr-simd.stderr b/tests/ui/feature-gates/feature-gate-repr-simd.stderr
new file mode 100644
index 000000000..5b1270a19
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-repr-simd.stderr
@@ -0,0 +1,35 @@
+error[E0658]: SIMD types are experimental and possibly buggy
+  --> $DIR/feature-gate-repr-simd.rs:1:1
+   |
+LL | #[repr(simd)]
+   | ^^^^^^^^^^^^^
+   |
+   = note: see issue #27731 <https://github.com/rust-lang/rust/issues/27731> for more information
+   = help: add `#![feature(repr_simd)]` to the crate attributes to enable
+
+error[E0658]: SIMD types are experimental and possibly buggy
+  --> $DIR/feature-gate-repr-simd.rs:6:1
+   |
+LL | #[repr(simd)]
+   | ^^^^^^^^^^^^^
+   |
+   = note: see issue #27731 <https://github.com/rust-lang/rust/issues/27731> for more information
+   = help: add `#![feature(repr_simd)]` to the crate attributes to enable
+
+error[E0566]: conflicting representation hints
+  --> $DIR/feature-gate-repr-simd.rs:4:8
+   |
+LL | #[repr(C)]
+   |        ^
+LL |
+LL | #[repr(simd)]
+   |        ^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #68585 <https://github.com/rust-lang/rust/issues/68585>
+   = note: `#[deny(conflicting_repr_hints)]` on by default
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0566, E0658.
+For more information about an error, try `rustc --explain E0566`.
diff --git a/tests/ui/feature-gates/feature-gate-repr128.rs b/tests/ui/feature-gates/feature-gate-repr128.rs
new file mode 100644
index 000000000..0290874dd
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-repr128.rs
@@ -0,0 +1,6 @@
+#[repr(u128)]
+enum A { //~ ERROR repr with 128-bit type is unstable
+    A(u64)
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-repr128.stderr b/tests/ui/feature-gates/feature-gate-repr128.stderr
new file mode 100644
index 000000000..3999a6d2d
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-repr128.stderr
@@ -0,0 +1,12 @@
+error[E0658]: repr with 128-bit type is unstable
+  --> $DIR/feature-gate-repr128.rs:2:1
+   |
+LL | enum A {
+   | ^^^^^^
+   |
+   = note: see issue #56071 <https://github.com/rust-lang/rust/issues/56071> for more information
+   = help: add `#![feature(repr128)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.rs b/tests/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.rs
new file mode 100644
index 000000000..637765fff
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.rs
@@ -0,0 +1,18 @@
+// edition:2021
+
+// async_fn_in_trait is not enough to allow use of RPITIT
+#![allow(incomplete_features)]
+#![feature(async_fn_in_trait)]
+
+trait Foo {
+    fn bar() -> impl Sized; //~ ERROR `impl Trait` only allowed in function and inherent method return types, not in trait method return
+    fn baz() -> Box<impl std::fmt::Display>; //~ ERROR `impl Trait` only allowed in function and inherent method return types, not in trait method return
+}
+
+// Both return_position_impl_trait_in_trait and async_fn_in_trait are required for this (see also
+// feature-gate-async_fn_in_trait.rs)
+trait AsyncFoo {
+    async fn bar() -> impl Sized; //~ ERROR `impl Trait` only allowed in function and inherent method return types, not in trait method return
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.stderr b/tests/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.stderr
new file mode 100644
index 000000000..aeabed4a6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.stderr
@@ -0,0 +1,30 @@
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return
+  --> $DIR/feature-gate-return_position_impl_trait_in_trait.rs:8:17
+   |
+LL |     fn bar() -> impl Sized;
+   |                 ^^^^^^^^^^
+   |
+   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
+   = help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
+
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return
+  --> $DIR/feature-gate-return_position_impl_trait_in_trait.rs:9:21
+   |
+LL |     fn baz() -> Box<impl std::fmt::Display>;
+   |                     ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
+   = help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
+
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return
+  --> $DIR/feature-gate-return_position_impl_trait_in_trait.rs:15:23
+   |
+LL |     async fn bar() -> impl Sized;
+   |                       ^^^^^^^^^^
+   |
+   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
+   = help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0562`.
diff --git a/tests/ui/feature-gates/feature-gate-rust_cold_cc.rs b/tests/ui/feature-gates/feature-gate-rust_cold_cc.rs
new file mode 100644
index 000000000..9ba8e32ac
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rust_cold_cc.rs
@@ -0,0 +1,21 @@
+#![crate_type = "lib"]
+
+extern "rust-cold" fn fu() {} //~ ERROR rust-cold is experimental
+
+trait T {
+    extern "rust-cold" fn mu(); //~ ERROR rust-cold is experimental
+    extern "rust-cold" fn dmu() {} //~ ERROR rust-cold is experimental
+}
+
+struct S;
+impl T for S {
+    extern "rust-cold" fn mu() {} //~ ERROR rust-cold is experimental
+}
+
+impl S {
+    extern "rust-cold" fn imu() {} //~ ERROR rust-cold is experimental
+}
+
+type TAU = extern "rust-cold" fn(); //~ ERROR rust-cold is experimental
+
+extern "rust-cold" {} //~ ERROR rust-cold is experimental
diff --git a/tests/ui/feature-gates/feature-gate-rust_cold_cc.stderr b/tests/ui/feature-gates/feature-gate-rust_cold_cc.stderr
new file mode 100644
index 000000000..ab7e5f036
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rust_cold_cc.stderr
@@ -0,0 +1,66 @@
+error[E0658]: rust-cold is experimental and subject to change
+  --> $DIR/feature-gate-rust_cold_cc.rs:3:8
+   |
+LL | extern "rust-cold" fn fu() {}
+   |        ^^^^^^^^^^^
+   |
+   = note: see issue #97544 <https://github.com/rust-lang/rust/issues/97544> for more information
+   = help: add `#![feature(rust_cold_cc)]` to the crate attributes to enable
+
+error[E0658]: rust-cold is experimental and subject to change
+  --> $DIR/feature-gate-rust_cold_cc.rs:6:12
+   |
+LL |     extern "rust-cold" fn mu();
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #97544 <https://github.com/rust-lang/rust/issues/97544> for more information
+   = help: add `#![feature(rust_cold_cc)]` to the crate attributes to enable
+
+error[E0658]: rust-cold is experimental and subject to change
+  --> $DIR/feature-gate-rust_cold_cc.rs:7:12
+   |
+LL |     extern "rust-cold" fn dmu() {}
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #97544 <https://github.com/rust-lang/rust/issues/97544> for more information
+   = help: add `#![feature(rust_cold_cc)]` to the crate attributes to enable
+
+error[E0658]: rust-cold is experimental and subject to change
+  --> $DIR/feature-gate-rust_cold_cc.rs:12:12
+   |
+LL |     extern "rust-cold" fn mu() {}
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #97544 <https://github.com/rust-lang/rust/issues/97544> for more information
+   = help: add `#![feature(rust_cold_cc)]` to the crate attributes to enable
+
+error[E0658]: rust-cold is experimental and subject to change
+  --> $DIR/feature-gate-rust_cold_cc.rs:16:12
+   |
+LL |     extern "rust-cold" fn imu() {}
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #97544 <https://github.com/rust-lang/rust/issues/97544> for more information
+   = help: add `#![feature(rust_cold_cc)]` to the crate attributes to enable
+
+error[E0658]: rust-cold is experimental and subject to change
+  --> $DIR/feature-gate-rust_cold_cc.rs:19:19
+   |
+LL | type TAU = extern "rust-cold" fn();
+   |                   ^^^^^^^^^^^
+   |
+   = note: see issue #97544 <https://github.com/rust-lang/rust/issues/97544> for more information
+   = help: add `#![feature(rust_cold_cc)]` to the crate attributes to enable
+
+error[E0658]: rust-cold is experimental and subject to change
+  --> $DIR/feature-gate-rust_cold_cc.rs:21:8
+   |
+LL | extern "rust-cold" {}
+   |        ^^^^^^^^^^^
+   |
+   = note: see issue #97544 <https://github.com/rust-lang/rust/issues/97544> for more information
+   = help: add `#![feature(rust_cold_cc)]` to the crate attributes to enable
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.rs b/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.rs
new file mode 100644
index 000000000..19d8fa87f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.rs
@@ -0,0 +1,6 @@
+#![allow(unused_macros)]
+
+#[rustc_allow_const_fn_unstable()] //~ ERROR rustc_allow_const_fn_unstable side-steps
+const fn foo() { }
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.stderr b/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.stderr
new file mode 100644
index 000000000..a549cb64e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rustc-allow-const-fn-unstable.stderr
@@ -0,0 +1,12 @@
+error[E0658]: rustc_allow_const_fn_unstable side-steps feature gating and stability checks
+  --> $DIR/feature-gate-rustc-allow-const-fn-unstable.rs:3:1
+   |
+LL | #[rustc_allow_const_fn_unstable()]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #69399 <https://github.com/rust-lang/rust/issues/69399> for more information
+   = help: add `#![feature(rustc_allow_const_fn_unstable)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs
new file mode 100644
index 000000000..667bc9f8d
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs
@@ -0,0 +1,7 @@
+// Test that `#[rustc_*]` attributes are gated by `rustc_attrs` feature gate.
+
+#[rustc_variance] //~ ERROR the `#[rustc_variance]` attribute is just used for rustc unit tests and will never be stable
+#[rustc_error] //~ ERROR the `#[rustc_error]` attribute is just used for rustc unit tests and will never be stable
+#[rustc_nonnull_optimization_guaranteed] //~ ERROR the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable niche optimizations in libcore and libstd and will never be stable
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr
new file mode 100644
index 000000000..45a095903
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr
@@ -0,0 +1,27 @@
+error[E0658]: the `#[rustc_variance]` attribute is just used for rustc unit tests and will never be stable
+  --> $DIR/feature-gate-rustc-attrs-1.rs:3:1
+   |
+LL | #[rustc_variance]
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+
+error[E0658]: the `#[rustc_error]` attribute is just used for rustc unit tests and will never be stable
+  --> $DIR/feature-gate-rustc-attrs-1.rs:4:1
+   |
+LL | #[rustc_error]
+   | ^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+
+error[E0658]: the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable niche optimizations in libcore and libstd and will never be stable
+  --> $DIR/feature-gate-rustc-attrs-1.rs:5:1
+   |
+LL | #[rustc_nonnull_optimization_guaranteed]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-rustc-attrs.rs b/tests/ui/feature-gates/feature-gate-rustc-attrs.rs
new file mode 100644
index 000000000..c985298a3
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rustc-attrs.rs
@@ -0,0 +1,23 @@
+// Test that `#[rustc_*]` attributes are gated by `rustc_attrs` feature gate.
+
+#![feature(decl_macro)]
+
+mod rustc { pub macro unknown() {} }
+mod unknown { pub macro rustc() {} }
+
+#[rustc::unknown]
+//~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
+//~| ERROR expected attribute, found macro `rustc::unknown`
+fn f() {}
+
+#[unknown::rustc]
+//~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
+//~| ERROR expected attribute, found macro `unknown::rustc`
+fn g() {}
+
+#[rustc_dummy]
+//~^ ERROR the `#[rustc_dummy]` attribute is just used for rustc unit tests
+#[rustc_unknown]
+//~^ ERROR attributes starting with `rustc` are reserved for use by the `rustc` compiler
+//~| ERROR cannot find attribute `rustc_unknown` in this scope
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-rustc-attrs.stderr b/tests/ui/feature-gates/feature-gate-rustc-attrs.stderr
new file mode 100644
index 000000000..1517a7a5c
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rustc-attrs.stderr
@@ -0,0 +1,47 @@
+error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
+  --> $DIR/feature-gate-rustc-attrs.rs:8:3
+   |
+LL | #[rustc::unknown]
+   |   ^^^^^
+
+error: expected attribute, found macro `rustc::unknown`
+  --> $DIR/feature-gate-rustc-attrs.rs:8:3
+   |
+LL | #[rustc::unknown]
+   |   ^^^^^^^^^^^^^^ not an attribute
+
+error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
+  --> $DIR/feature-gate-rustc-attrs.rs:13:12
+   |
+LL | #[unknown::rustc]
+   |            ^^^^^
+
+error: expected attribute, found macro `unknown::rustc`
+  --> $DIR/feature-gate-rustc-attrs.rs:13:3
+   |
+LL | #[unknown::rustc]
+   |   ^^^^^^^^^^^^^^ not an attribute
+
+error: attributes starting with `rustc` are reserved for use by the `rustc` compiler
+  --> $DIR/feature-gate-rustc-attrs.rs:20:3
+   |
+LL | #[rustc_unknown]
+   |   ^^^^^^^^^^^^^
+
+error: cannot find attribute `rustc_unknown` in this scope
+  --> $DIR/feature-gate-rustc-attrs.rs:20:3
+   |
+LL | #[rustc_unknown]
+   |   ^^^^^^^^^^^^^
+
+error[E0658]: the `#[rustc_dummy]` attribute is just used for rustc unit tests and will never be stable
+  --> $DIR/feature-gate-rustc-attrs.rs:18:1
+   |
+LL | #[rustc_dummy]
+   | ^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-rustc_const_unstable.rs b/tests/ui/feature-gates/feature-gate-rustc_const_unstable.rs
new file mode 100644
index 000000000..d7daaaaa1
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rustc_const_unstable.rs
@@ -0,0 +1,7 @@
+// Test internal const fn feature gate.
+
+#[rustc_const_unstable(feature="fzzzzzt")] //~ stability attributes may not be used outside
+pub const fn bazinga() {}
+
+fn main() {
+}
diff --git a/tests/ui/feature-gates/feature-gate-rustc_const_unstable.stderr b/tests/ui/feature-gates/feature-gate-rustc_const_unstable.stderr
new file mode 100644
index 000000000..48493b786
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rustc_const_unstable.stderr
@@ -0,0 +1,9 @@
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/feature-gate-rustc_const_unstable.rs:3:1
+   |
+LL | #[rustc_const_unstable(feature="fzzzzzt")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0734`.
diff --git a/tests/ui/feature-gates/feature-gate-rustdoc_internals.rs b/tests/ui/feature-gates/feature-gate-rustdoc_internals.rs
new file mode 100644
index 000000000..58306a4cf
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rustdoc_internals.rs
@@ -0,0 +1,10 @@
+#[doc(keyword = "match")] //~ ERROR: `#[doc(keyword)]` is meant for internal use only
+/// wonderful
+mod foo {}
+
+trait Mine {}
+
+#[doc(fake_variadic)]  //~ ERROR: `#[doc(fake_variadic)]` is meant for internal use only
+impl<T> Mine for (T,) {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-rustdoc_internals.stderr b/tests/ui/feature-gates/feature-gate-rustdoc_internals.stderr
new file mode 100644
index 000000000..c4272a2c0
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-rustdoc_internals.stderr
@@ -0,0 +1,21 @@
+error[E0658]: `#[doc(keyword)]` is meant for internal use only
+  --> $DIR/feature-gate-rustdoc_internals.rs:1:1
+   |
+LL | #[doc(keyword = "match")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #90418 <https://github.com/rust-lang/rust/issues/90418> for more information
+   = help: add `#![feature(rustdoc_internals)]` to the crate attributes to enable
+
+error[E0658]: `#[doc(fake_variadic)]` is meant for internal use only
+  --> $DIR/feature-gate-rustdoc_internals.rs:7:1
+   |
+LL | #[doc(fake_variadic)]
+   | ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #90418 <https://github.com/rust-lang/rust/issues/90418> for more information
+   = help: add `#![feature(rustdoc_internals)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-simd-ffi.rs b/tests/ui/feature-gates/feature-gate-simd-ffi.rs
new file mode 100644
index 000000000..abffa4a10
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-simd-ffi.rs
@@ -0,0 +1,13 @@
+#![feature(repr_simd)]
+#![allow(dead_code)]
+
+#[repr(simd)]
+#[derive(Copy, Clone)]
+struct LocalSimd(u8, u8);
+
+extern "C" {
+    fn baz() -> LocalSimd; //~ ERROR use of SIMD type
+    fn qux(x: LocalSimd); //~ ERROR use of SIMD type
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-simd-ffi.stderr b/tests/ui/feature-gates/feature-gate-simd-ffi.stderr
new file mode 100644
index 000000000..8166b6baa
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-simd-ffi.stderr
@@ -0,0 +1,18 @@
+error: use of SIMD type `LocalSimd` in FFI is highly experimental and may result in invalid code
+  --> $DIR/feature-gate-simd-ffi.rs:9:17
+   |
+LL |     fn baz() -> LocalSimd;
+   |                 ^^^^^^^^^
+   |
+   = help: add `#![feature(simd_ffi)]` to the crate attributes to enable
+
+error: use of SIMD type `LocalSimd` in FFI is highly experimental and may result in invalid code
+  --> $DIR/feature-gate-simd-ffi.rs:10:15
+   |
+LL |     fn qux(x: LocalSimd);
+   |               ^^^^^^^^^
+   |
+   = help: add `#![feature(simd_ffi)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/feature-gates/feature-gate-simd.rs b/tests/ui/feature-gates/feature-gate-simd.rs
new file mode 100644
index 000000000..d01d33de2
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-simd.rs
@@ -0,0 +1,11 @@
+// pretty-expanded FIXME #23616
+
+#[repr(simd)] //~ ERROR SIMD types are experimental
+struct RGBA {
+    r: f32,
+    g: f32,
+    b: f32,
+    a: f32
+}
+
+pub fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-simd.stderr b/tests/ui/feature-gates/feature-gate-simd.stderr
new file mode 100644
index 000000000..6e0e0b270
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-simd.stderr
@@ -0,0 +1,12 @@
+error[E0658]: SIMD types are experimental and possibly buggy
+  --> $DIR/feature-gate-simd.rs:3:1
+   |
+LL | #[repr(simd)]
+   | ^^^^^^^^^^^^^
+   |
+   = note: see issue #27731 <https://github.com/rust-lang/rust/issues/27731> for more information
+   = help: add `#![feature(repr_simd)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-staged_api.rs b/tests/ui/feature-gates/feature-gate-staged_api.rs
new file mode 100644
index 000000000..2571ab5d1
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-staged_api.rs
@@ -0,0 +1,14 @@
+#![stable(feature = "a", since = "b")]
+//~^ ERROR stability attributes may not be used outside of the standard library
+mod inner_private_module {
+    // UnnameableTypeAlias isn't marked as reachable, so no stability annotation is required here
+    pub type UnnameableTypeAlias = u8;
+}
+
+#[stable(feature = "a", since = "b")]
+//~^ ERROR stability attributes may not be used outside of the standard library
+pub fn f() -> inner_private_module::UnnameableTypeAlias {
+    0
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-staged_api.stderr b/tests/ui/feature-gates/feature-gate-staged_api.stderr
new file mode 100644
index 000000000..951bb5a17
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-staged_api.stderr
@@ -0,0 +1,15 @@
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/feature-gate-staged_api.rs:8:1
+   |
+LL | #[stable(feature = "a", since = "b")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/feature-gate-staged_api.rs:1:1
+   |
+LL | #![stable(feature = "a", since = "b")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0734`.
diff --git a/tests/ui/feature-gates/feature-gate-start.rs b/tests/ui/feature-gates/feature-gate-start.rs
new file mode 100644
index 000000000..e617f1c47
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-start.rs
@@ -0,0 +1,3 @@
+#[start]
+fn foo(_: isize, _: *const *const u8) -> isize { 0 }
+//~^ ERROR `#[start]` functions are experimental
diff --git a/tests/ui/feature-gates/feature-gate-start.stderr b/tests/ui/feature-gates/feature-gate-start.stderr
new file mode 100644
index 000000000..eec9d1a29
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-start.stderr
@@ -0,0 +1,12 @@
+error[E0658]: `#[start]` functions are experimental and their signature may change over time
+  --> $DIR/feature-gate-start.rs:2:1
+   |
+LL | fn foo(_: isize, _: *const *const u8) -> isize { 0 }
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #29633 <https://github.com/rust-lang/rust/issues/29633> for more information
+   = help: add `#![feature(start)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-stmt_expr_attributes.rs b/tests/ui/feature-gates/feature-gate-stmt_expr_attributes.rs
new file mode 100644
index 000000000..f213e8933
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-stmt_expr_attributes.rs
@@ -0,0 +1,4 @@
+const X: i32 = #[allow(dead_code)] 8;
+//~^ ERROR attributes on expressions are experimental
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-stmt_expr_attributes.stderr b/tests/ui/feature-gates/feature-gate-stmt_expr_attributes.stderr
new file mode 100644
index 000000000..57ffaed78
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-stmt_expr_attributes.stderr
@@ -0,0 +1,12 @@
+error[E0658]: attributes on expressions are experimental
+  --> $DIR/feature-gate-stmt_expr_attributes.rs:1:16
+   |
+LL | const X: i32 = #[allow(dead_code)] 8;
+   |                ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #15701 <https://github.com/rust-lang/rust/issues/15701> for more information
+   = help: add `#![feature(stmt_expr_attributes)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-strict_provenance.rs b/tests/ui/feature-gates/feature-gate-strict_provenance.rs
new file mode 100644
index 000000000..75d0ee570
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-strict_provenance.rs
@@ -0,0 +1,19 @@
+// check-pass
+
+#![deny(fuzzy_provenance_casts)]
+//~^ WARNING unknown lint: `fuzzy_provenance_casts`
+//~| WARNING unknown lint: `fuzzy_provenance_casts`
+//~| WARNING unknown lint: `fuzzy_provenance_casts`
+#![deny(lossy_provenance_casts)]
+//~^ WARNING unknown lint: `lossy_provenance_casts`
+//~| WARNING unknown lint: `lossy_provenance_casts`
+//~| WARNING unknown lint: `lossy_provenance_casts`
+
+fn main() {
+    // no warnings emitted since the lints are not activated
+
+    let _dangling = 16_usize as *const u8;
+
+    let x: u8 = 37;
+    let _addr: usize = &x as *const u8 as usize;
+}
diff --git a/tests/ui/feature-gates/feature-gate-strict_provenance.stderr b/tests/ui/feature-gates/feature-gate-strict_provenance.stderr
new file mode 100644
index 000000000..751da87cc
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-strict_provenance.stderr
@@ -0,0 +1,63 @@
+warning: unknown lint: `fuzzy_provenance_casts`
+  --> $DIR/feature-gate-strict_provenance.rs:3:1
+   |
+LL | #![deny(fuzzy_provenance_casts)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `fuzzy_provenance_casts` lint is unstable
+   = note: see issue #95228 <https://github.com/rust-lang/rust/issues/95228> for more information
+   = help: add `#![feature(strict_provenance)]` to the crate attributes to enable
+   = note: `#[warn(unknown_lints)]` on by default
+
+warning: unknown lint: `lossy_provenance_casts`
+  --> $DIR/feature-gate-strict_provenance.rs:7:1
+   |
+LL | #![deny(lossy_provenance_casts)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `lossy_provenance_casts` lint is unstable
+   = note: see issue #95228 <https://github.com/rust-lang/rust/issues/95228> for more information
+   = help: add `#![feature(strict_provenance)]` to the crate attributes to enable
+
+warning: unknown lint: `fuzzy_provenance_casts`
+  --> $DIR/feature-gate-strict_provenance.rs:3:1
+   |
+LL | #![deny(fuzzy_provenance_casts)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `fuzzy_provenance_casts` lint is unstable
+   = note: see issue #95228 <https://github.com/rust-lang/rust/issues/95228> for more information
+   = help: add `#![feature(strict_provenance)]` to the crate attributes to enable
+
+warning: unknown lint: `lossy_provenance_casts`
+  --> $DIR/feature-gate-strict_provenance.rs:7:1
+   |
+LL | #![deny(lossy_provenance_casts)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `lossy_provenance_casts` lint is unstable
+   = note: see issue #95228 <https://github.com/rust-lang/rust/issues/95228> for more information
+   = help: add `#![feature(strict_provenance)]` to the crate attributes to enable
+
+warning: unknown lint: `fuzzy_provenance_casts`
+  --> $DIR/feature-gate-strict_provenance.rs:3:1
+   |
+LL | #![deny(fuzzy_provenance_casts)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `fuzzy_provenance_casts` lint is unstable
+   = note: see issue #95228 <https://github.com/rust-lang/rust/issues/95228> for more information
+   = help: add `#![feature(strict_provenance)]` to the crate attributes to enable
+
+warning: unknown lint: `lossy_provenance_casts`
+  --> $DIR/feature-gate-strict_provenance.rs:7:1
+   |
+LL | #![deny(lossy_provenance_casts)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `lossy_provenance_casts` lint is unstable
+   = note: see issue #95228 <https://github.com/rust-lang/rust/issues/95228> for more information
+   = help: add `#![feature(strict_provenance)]` to the crate attributes to enable
+
+warning: 6 warnings emitted
+
diff --git a/tests/ui/feature-gates/feature-gate-test_unstable_lint.rs b/tests/ui/feature-gates/feature-gate-test_unstable_lint.rs
new file mode 100644
index 000000000..c398394cb
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-test_unstable_lint.rs
@@ -0,0 +1,9 @@
+// check-pass
+
+// `test_unstable_lint` is for testing and should never be stabilized.
+#![allow(test_unstable_lint)]
+//~^ WARNING unknown lint: `test_unstable_lint`
+//~| WARNING unknown lint: `test_unstable_lint`
+//~| WARNING unknown lint: `test_unstable_lint`
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-test_unstable_lint.stderr b/tests/ui/feature-gates/feature-gate-test_unstable_lint.stderr
new file mode 100644
index 000000000..b4d6aa658
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-test_unstable_lint.stderr
@@ -0,0 +1,30 @@
+warning: unknown lint: `test_unstable_lint`
+  --> $DIR/feature-gate-test_unstable_lint.rs:4:1
+   |
+LL | #![allow(test_unstable_lint)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `test_unstable_lint` lint is unstable
+   = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
+   = note: `#[warn(unknown_lints)]` on by default
+
+warning: unknown lint: `test_unstable_lint`
+  --> $DIR/feature-gate-test_unstable_lint.rs:4:1
+   |
+LL | #![allow(test_unstable_lint)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `test_unstable_lint` lint is unstable
+   = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
+
+warning: unknown lint: `test_unstable_lint`
+  --> $DIR/feature-gate-test_unstable_lint.rs:4:1
+   |
+LL | #![allow(test_unstable_lint)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: the `test_unstable_lint` lint is unstable
+   = help: add `#![feature(test_unstable_lint)]` to the crate attributes to enable
+
+warning: 3 warnings emitted
+
diff --git a/tests/ui/feature-gates/feature-gate-thread_local.rs b/tests/ui/feature-gates/feature-gate-thread_local.rs
new file mode 100644
index 000000000..0efae1f6b
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-thread_local.rs
@@ -0,0 +1,11 @@
+// Test that `#[thread_local]` attribute is gated by `thread_local`
+// feature gate.
+//
+// (Note that the `thread_local!` macro is explicitly *not* gated; it
+// is given permission to expand into this unstable attribute even
+// when the surrounding context does not have permission to use it.)
+
+#[thread_local] //~ ERROR `#[thread_local]` is an experimental feature
+static FOO: i32 = 3;
+
+pub fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-thread_local.stderr b/tests/ui/feature-gates/feature-gate-thread_local.stderr
new file mode 100644
index 000000000..6352e9087
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-thread_local.stderr
@@ -0,0 +1,12 @@
+error[E0658]: `#[thread_local]` is an experimental feature, and does not currently handle destructors
+  --> $DIR/feature-gate-thread_local.rs:8:1
+   |
+LL | #[thread_local]
+   | ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #29594 <https://github.com/rust-lang/rust/issues/29594> for more information
+   = help: add `#![feature(thread_local)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-trace_macros.rs b/tests/ui/feature-gates/feature-gate-trace_macros.rs
new file mode 100644
index 000000000..07159b7b5
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-trace_macros.rs
@@ -0,0 +1,3 @@
+fn main() {
+    trace_macros!(true); //~ ERROR: `trace_macros` is not stable
+}
diff --git a/tests/ui/feature-gates/feature-gate-trace_macros.stderr b/tests/ui/feature-gates/feature-gate-trace_macros.stderr
new file mode 100644
index 000000000..3978d4111
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-trace_macros.stderr
@@ -0,0 +1,12 @@
+error[E0658]: use of unstable library feature 'trace_macros': `trace_macros` is not stable enough for use and is subject to change
+  --> $DIR/feature-gate-trace_macros.rs:2:5
+   |
+LL |     trace_macros!(true);
+   |     ^^^^^^^^^^^^
+   |
+   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
+   = help: add `#![feature(trace_macros)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-trait-alias.rs b/tests/ui/feature-gates/feature-gate-trait-alias.rs
new file mode 100644
index 000000000..819085add
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-trait-alias.rs
@@ -0,0 +1,4 @@
+trait Foo = Default;
+//~^ ERROR trait aliases are experimental
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-trait-alias.stderr b/tests/ui/feature-gates/feature-gate-trait-alias.stderr
new file mode 100644
index 000000000..41cd6dbd8
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-trait-alias.stderr
@@ -0,0 +1,12 @@
+error[E0658]: trait aliases are experimental
+  --> $DIR/feature-gate-trait-alias.rs:1:1
+   |
+LL | trait Foo = Default;
+   | ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #41517 <https://github.com/rust-lang/rust/issues/41517> for more information
+   = help: add `#![feature(trait_alias)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-trait_upcasting.rs b/tests/ui/feature-gates/feature-gate-trait_upcasting.rs
new file mode 100644
index 000000000..e4102f1cf
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-trait_upcasting.rs
@@ -0,0 +1,13 @@
+trait Foo {}
+
+trait Bar: Foo {}
+
+impl Foo for () {}
+
+impl Bar for () {}
+
+fn main() {
+    let bar: &dyn Bar = &();
+    let foo: &dyn Foo = bar;
+    //~^ ERROR trait upcasting coercion is experimental [E0658]
+}
diff --git a/tests/ui/feature-gates/feature-gate-trait_upcasting.stderr b/tests/ui/feature-gates/feature-gate-trait_upcasting.stderr
new file mode 100644
index 000000000..93afa7845
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-trait_upcasting.stderr
@@ -0,0 +1,13 @@
+error[E0658]: cannot cast `dyn Bar` to `dyn Foo`, trait upcasting coercion is experimental
+  --> $DIR/feature-gate-trait_upcasting.rs:11:25
+   |
+LL |     let foo: &dyn Foo = bar;
+   |                         ^^^
+   |
+   = note: see issue #65991 <https://github.com/rust-lang/rust/issues/65991> for more information
+   = help: add `#![feature(trait_upcasting)]` to the crate attributes to enable
+   = note: required when coercing `&dyn Bar` into `&dyn Foo`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-transparent_unions.rs b/tests/ui/feature-gates/feature-gate-transparent_unions.rs
new file mode 100644
index 000000000..73cac0a49
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-transparent_unions.rs
@@ -0,0 +1,7 @@
+#[repr(transparent)]
+union OkButUnstableUnion { //~ ERROR transparent unions are unstable
+    field: u8,
+    zst: (),
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-transparent_unions.stderr b/tests/ui/feature-gates/feature-gate-transparent_unions.stderr
new file mode 100644
index 000000000..65c8fe052
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-transparent_unions.stderr
@@ -0,0 +1,12 @@
+error[E0658]: transparent unions are unstable
+  --> $DIR/feature-gate-transparent_unions.rs:2:1
+   |
+LL | union OkButUnstableUnion {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #60405 <https://github.com/rust-lang/rust/issues/60405> for more information
+   = help: add `#![feature(transparent_unions)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-trivial_bounds-lint.rs b/tests/ui/feature-gates/feature-gate-trivial_bounds-lint.rs
new file mode 100644
index 000000000..8f68d5d6d
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-trivial_bounds-lint.rs
@@ -0,0 +1,8 @@
+// run-pass
+
+#![allow(unused)]
+#![deny(trivial_bounds)] // Ignored without the trivial_bounds feature flag.
+
+struct A where i32: Copy;
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-trivial_bounds.rs b/tests/ui/feature-gates/feature-gate-trivial_bounds.rs
new file mode 100644
index 000000000..3dbaf5dea
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-trivial_bounds.rs
@@ -0,0 +1,69 @@
+#![allow(unused)]
+#![allow(type_alias_bounds)]
+
+pub trait Foo {
+    fn test(&self);
+}
+
+fn generic_function<X: Foo>(x: X) {}
+
+enum E where i32: Foo { V } //~ ERROR
+
+struct S where i32: Foo; //~ ERROR
+
+trait T where i32: Foo {} //~ ERROR
+
+union U where i32: Foo { f: i32 } //~ ERROR
+
+type Y where i32: Foo = (); // OK - bound is ignored
+
+impl Foo for () where i32: Foo { //~ ERROR
+    fn test(&self) {
+        3i32.test();
+        Foo::test(&4i32);
+        generic_function(5i32);
+    }
+}
+
+fn f() where i32: Foo //~ ERROR
+{
+    let s = S;
+    3i32.test();
+    Foo::test(&4i32);
+    generic_function(5i32);
+}
+
+fn use_op(s: String) -> String where String: ::std::ops::Neg<Output=String> { //~ ERROR
+    -s
+}
+
+fn use_for() where i32: Iterator { //~ ERROR
+    for _ in 2i32 {}
+}
+
+trait A {}
+
+impl A for i32 {}
+
+struct Dst<X: ?Sized> {
+    x: X,
+}
+
+struct TwoStrs(str, str) where str: Sized; //~ ERROR
+
+
+fn unsized_local() where Dst<dyn A>: Sized { //~ ERROR
+    let x: Dst<dyn A> = *(Box::new(Dst { x: 1 }) as Box<Dst<dyn A>>);
+}
+
+fn return_str() -> str where str: Sized { //~ ERROR
+    *"Sized".to_string().into_boxed_str()
+}
+
+// This is currently accepted because the function pointer isn't
+// considered global.
+fn global_hr(x: fn(&())) where fn(&()): Foo { // OK
+    x.test();
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-trivial_bounds.stderr b/tests/ui/feature-gates/feature-gate-trivial_bounds.stderr
new file mode 100644
index 000000000..1b87ebd9f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-trivial_bounds.stderr
@@ -0,0 +1,118 @@
+error[E0277]: the trait bound `i32: Foo` is not satisfied
+  --> $DIR/feature-gate-trivial_bounds.rs:10:14
+   |
+LL | enum E where i32: Foo { V }
+   |              ^^^^^^^^ the trait `Foo` is not implemented for `i32`
+   |
+   = help: the trait `Foo` is implemented for `()`
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error[E0277]: the trait bound `i32: Foo` is not satisfied
+  --> $DIR/feature-gate-trivial_bounds.rs:12:16
+   |
+LL | struct S where i32: Foo;
+   |                ^^^^^^^^ the trait `Foo` is not implemented for `i32`
+   |
+   = help: the trait `Foo` is implemented for `()`
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error[E0277]: the trait bound `i32: Foo` is not satisfied
+  --> $DIR/feature-gate-trivial_bounds.rs:14:15
+   |
+LL | trait T where i32: Foo {}
+   |               ^^^^^^^^ the trait `Foo` is not implemented for `i32`
+   |
+   = help: the trait `Foo` is implemented for `()`
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error[E0277]: the trait bound `i32: Foo` is not satisfied
+  --> $DIR/feature-gate-trivial_bounds.rs:16:15
+   |
+LL | union U where i32: Foo { f: i32 }
+   |               ^^^^^^^^ the trait `Foo` is not implemented for `i32`
+   |
+   = help: the trait `Foo` is implemented for `()`
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error[E0277]: the trait bound `i32: Foo` is not satisfied
+  --> $DIR/feature-gate-trivial_bounds.rs:20:23
+   |
+LL | impl Foo for () where i32: Foo {
+   |                       ^^^^^^^^ the trait `Foo` is not implemented for `i32`
+   |
+   = help: the trait `Foo` is implemented for `()`
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error[E0277]: the trait bound `i32: Foo` is not satisfied
+  --> $DIR/feature-gate-trivial_bounds.rs:28:14
+   |
+LL | fn f() where i32: Foo
+   |              ^^^^^^^^ the trait `Foo` is not implemented for `i32`
+   |
+   = help: the trait `Foo` is implemented for `()`
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error[E0277]: the trait bound `String: Neg` is not satisfied
+  --> $DIR/feature-gate-trivial_bounds.rs:36:38
+   |
+LL | fn use_op(s: String) -> String where String: ::std::ops::Neg<Output=String> {
+   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Neg` is not implemented for `String`
+   |
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error[E0277]: `i32` is not an iterator
+  --> $DIR/feature-gate-trivial_bounds.rs:40:20
+   |
+LL | fn use_for() where i32: Iterator {
+   |                    ^^^^^^^^^^^^^ `i32` is not an iterator
+   |
+   = help: the trait `Iterator` is not implemented for `i32`
+   = note: if you want to iterate between `start` until a value `end`, use the exclusive range syntax `start..end` or the inclusive range syntax `start..=end`
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/feature-gate-trivial_bounds.rs:52:32
+   |
+LL | struct TwoStrs(str, str) where str: Sized;
+   |                                ^^^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error[E0277]: the size for values of type `(dyn A + 'static)` cannot be known at compilation time
+  --> $DIR/feature-gate-trivial_bounds.rs:55:26
+   |
+LL | fn unsized_local() where Dst<dyn A>: Sized {
+   |                          ^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: within `Dst<(dyn A + 'static)>`, the trait `Sized` is not implemented for `(dyn A + 'static)`
+note: required because it appears within the type `Dst<(dyn A + 'static)>`
+  --> $DIR/feature-gate-trivial_bounds.rs:48:8
+   |
+LL | struct Dst<X: ?Sized> {
+   |        ^^^
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/feature-gate-trivial_bounds.rs:59:30
+   |
+LL | fn return_str() -> str where str: Sized {
+   |                              ^^^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `str`
+   = help: see issue #48214
+   = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+
+error: aborting due to 11 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/feature-gates/feature-gate-try_blocks.rs b/tests/ui/feature-gates/feature-gate-try_blocks.rs
new file mode 100644
index 000000000..06cadd82c
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-try_blocks.rs
@@ -0,0 +1,9 @@
+// compile-flags: --edition 2018
+
+pub fn main() {
+    let try_result: Option<_> = try { //~ ERROR `try` expression is experimental
+        let x = 5;
+        x
+    };
+    assert_eq!(try_result, Some(5));
+}
diff --git a/tests/ui/feature-gates/feature-gate-try_blocks.stderr b/tests/ui/feature-gates/feature-gate-try_blocks.stderr
new file mode 100644
index 000000000..022409f95
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-try_blocks.stderr
@@ -0,0 +1,16 @@
+error[E0658]: `try` expression is experimental
+  --> $DIR/feature-gate-try_blocks.rs:4:33
+   |
+LL |       let try_result: Option<_> = try {
+   |  _________________________________^
+LL | |         let x = 5;
+LL | |         x
+LL | |     };
+   | |_____^
+   |
+   = note: see issue #31436 <https://github.com/rust-lang/rust/issues/31436> for more information
+   = help: add `#![feature(try_blocks)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-type_alias_impl_trait.rs b/tests/ui/feature-gates/feature-gate-type_alias_impl_trait.rs
new file mode 100644
index 000000000..6dfd7f684
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-type_alias_impl_trait.rs
@@ -0,0 +1,34 @@
+// ignore-compare-mode-chalk
+// check-pass
+#![feature(type_alias_impl_trait)]
+use std::fmt::Debug;
+
+type Foo = impl Debug;
+
+struct Bar(Foo);
+fn define() -> Bar {
+    Bar(42)
+}
+
+type Foo2 = impl Debug;
+
+fn define2() {
+    let x = || -> Foo2 { 42 };
+}
+
+type Foo3 = impl Debug;
+
+fn define3(x: Foo3) {
+    let y: i32 = x;
+}
+fn define3_1() {
+    define3(42)
+}
+
+type Foo4 = impl Debug;
+
+fn define4() {
+    let y: Foo4 = 42;
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-type_ascription.rs b/tests/ui/feature-gates/feature-gate-type_ascription.rs
new file mode 100644
index 000000000..7a5971573
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-type_ascription.rs
@@ -0,0 +1,5 @@
+// Type ascription is unstable
+
+fn main() {
+    let a = 10: u8; //~ ERROR type ascription is experimental
+}
diff --git a/tests/ui/feature-gates/feature-gate-type_ascription.stderr b/tests/ui/feature-gates/feature-gate-type_ascription.stderr
new file mode 100644
index 000000000..615d5b9a1
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-type_ascription.stderr
@@ -0,0 +1,12 @@
+error[E0658]: type ascription is experimental
+  --> $DIR/feature-gate-type_ascription.rs:4:13
+   |
+LL |     let a = 10: u8;
+   |             ^^^^^^
+   |
+   = note: see issue #23416 <https://github.com/rust-lang/rust/issues/23416> for more information
+   = help: add `#![feature(type_ascription)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.rs b/tests/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.rs
new file mode 100644
index 000000000..eecf2046c
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.rs
@@ -0,0 +1,37 @@
+// Test that manual impls of the `Fn` traits are not possible without
+// a feature gate. In fact, the specialized check for these cases
+// never triggers (yet), because they encounter other problems around
+// angle bracket vs parentheses notation.
+
+#![feature(fn_traits)]
+
+struct Foo;
+impl Fn<()> for Foo {
+//~^ ERROR the precise format of `Fn`-family traits' type parameters is subject to change
+//~| ERROR manual implementations of `Fn` are experimental
+    extern "rust-call" fn call(self, args: ()) -> () {}
+    //~^ ERROR rust-call ABI is subject to change
+}
+struct Foo1;
+impl FnOnce() for Foo1 {
+//~^ ERROR associated type bindings are not allowed here
+//~| ERROR manual implementations of `FnOnce` are experimental
+    extern "rust-call" fn call_once(self, args: ()) -> () {}
+    //~^ ERROR rust-call ABI is subject to change
+}
+struct Bar;
+impl FnMut<()> for Bar {
+//~^ ERROR the precise format of `Fn`-family traits' type parameters is subject to change
+//~| ERROR manual implementations of `FnMut` are experimental
+    extern "rust-call" fn call_mut(&self, args: ()) -> () {}
+    //~^ ERROR rust-call ABI is subject to change
+}
+struct Baz;
+impl FnOnce<()> for Baz {
+//~^ ERROR the precise format of `Fn`-family traits' type parameters is subject to change
+//~| ERROR manual implementations of `FnOnce` are experimental
+    extern "rust-call" fn call_once(&self, args: ()) -> () {}
+    //~^ ERROR rust-call ABI is subject to change
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr b/tests/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr
new file mode 100644
index 000000000..f647380ef
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unboxed-closures-manual-impls.stderr
@@ -0,0 +1,105 @@
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:12:12
+   |
+LL |     extern "rust-call" fn call(self, args: ()) -> () {}
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:19:12
+   |
+LL |     extern "rust-call" fn call_once(self, args: ()) -> () {}
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:26:12
+   |
+LL |     extern "rust-call" fn call_mut(&self, args: ()) -> () {}
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:33:12
+   |
+LL |     extern "rust-call" fn call_once(&self, args: ()) -> () {}
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: the precise format of `Fn`-family traits' type parameters is subject to change
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:9:6
+   |
+LL | impl Fn<()> for Foo {
+   |      ^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0183]: manual implementations of `Fn` are experimental
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:9:6
+   |
+LL | impl Fn<()> for Foo {
+   |      ^^^^^^ manual implementations of `Fn` are experimental
+   |
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0183]: manual implementations of `FnOnce` are experimental
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:16:6
+   |
+LL | impl FnOnce() for Foo1 {
+   |      ^^^^^^^^ manual implementations of `FnOnce` are experimental
+   |
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0229]: associated type bindings are not allowed here
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:16:6
+   |
+LL | impl FnOnce() for Foo1 {
+   |      ^^^^^^^^ associated type not allowed here
+
+error[E0658]: the precise format of `Fn`-family traits' type parameters is subject to change
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:23:6
+   |
+LL | impl FnMut<()> for Bar {
+   |      ^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0183]: manual implementations of `FnMut` are experimental
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:23:6
+   |
+LL | impl FnMut<()> for Bar {
+   |      ^^^^^^^^^ manual implementations of `FnMut` are experimental
+   |
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: the precise format of `Fn`-family traits' type parameters is subject to change
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:30:6
+   |
+LL | impl FnOnce<()> for Baz {
+   |      ^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0183]: manual implementations of `FnOnce` are experimental
+  --> $DIR/feature-gate-unboxed-closures-manual-impls.rs:30:6
+   |
+LL | impl FnOnce<()> for Baz {
+   |      ^^^^^^^^^^ manual implementations of `FnOnce` are experimental
+   |
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error: aborting due to 12 previous errors
+
+Some errors have detailed explanations: E0183, E0229, E0658.
+For more information about an error, try `rustc --explain E0183`.
diff --git a/tests/ui/feature-gates/feature-gate-unboxed-closures-method-calls.rs b/tests/ui/feature-gates/feature-gate-unboxed-closures-method-calls.rs
new file mode 100644
index 000000000..42f7c5f0f
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unboxed-closures-method-calls.rs
@@ -0,0 +1,9 @@
+#![allow(dead_code)]
+
+fn foo<F: Fn()>(mut f: F) {
+    f.call(()); //~ ERROR use of unstable library feature 'fn_traits'
+    f.call_mut(()); //~ ERROR use of unstable library feature 'fn_traits'
+    f.call_once(()); //~ ERROR use of unstable library feature 'fn_traits'
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-unboxed-closures-method-calls.stderr b/tests/ui/feature-gates/feature-gate-unboxed-closures-method-calls.stderr
new file mode 100644
index 000000000..c61382c64
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unboxed-closures-method-calls.stderr
@@ -0,0 +1,30 @@
+error[E0658]: use of unstable library feature 'fn_traits'
+  --> $DIR/feature-gate-unboxed-closures-method-calls.rs:4:7
+   |
+LL |     f.call(());
+   |       ^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(fn_traits)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'fn_traits'
+  --> $DIR/feature-gate-unboxed-closures-method-calls.rs:5:7
+   |
+LL |     f.call_mut(());
+   |       ^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(fn_traits)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'fn_traits'
+  --> $DIR/feature-gate-unboxed-closures-method-calls.rs:6:7
+   |
+LL |     f.call_once(());
+   |       ^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(fn_traits)]` to the crate attributes to enable
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-unboxed-closures-ufcs-calls.rs b/tests/ui/feature-gates/feature-gate-unboxed-closures-ufcs-calls.rs
new file mode 100644
index 000000000..25c90492e
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unboxed-closures-ufcs-calls.rs
@@ -0,0 +1,9 @@
+#![allow(dead_code)]
+
+fn foo<F: Fn()>(mut f: F) {
+    Fn::call(&f, ()); //~ ERROR use of unstable library feature 'fn_traits'
+    FnMut::call_mut(&mut f, ()); //~ ERROR use of unstable library feature 'fn_traits'
+    FnOnce::call_once(f, ()); //~ ERROR use of unstable library feature 'fn_traits'
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-unboxed-closures-ufcs-calls.stderr b/tests/ui/feature-gates/feature-gate-unboxed-closures-ufcs-calls.stderr
new file mode 100644
index 000000000..50eaeecde
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unboxed-closures-ufcs-calls.stderr
@@ -0,0 +1,30 @@
+error[E0658]: use of unstable library feature 'fn_traits'
+  --> $DIR/feature-gate-unboxed-closures-ufcs-calls.rs:4:5
+   |
+LL |     Fn::call(&f, ());
+   |     ^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(fn_traits)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'fn_traits'
+  --> $DIR/feature-gate-unboxed-closures-ufcs-calls.rs:5:5
+   |
+LL |     FnMut::call_mut(&mut f, ());
+   |     ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(fn_traits)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'fn_traits'
+  --> $DIR/feature-gate-unboxed-closures-ufcs-calls.rs:6:5
+   |
+LL |     FnOnce::call_once(f, ());
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(fn_traits)]` to the crate attributes to enable
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-unboxed-closures.rs b/tests/ui/feature-gates/feature-gate-unboxed-closures.rs
new file mode 100644
index 000000000..ebc5a2536
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unboxed-closures.rs
@@ -0,0 +1,18 @@
+#![feature(fn_traits)]
+
+struct Test;
+
+impl FnOnce<(u32, u32)> for Test {
+//~^ ERROR the precise format of `Fn`-family traits' type parameters is subject to change
+//~| ERROR manual implementations of `FnOnce` are experimental
+    type Output = u32;
+
+    extern "rust-call" fn call_once(self, (a, b): (u32, u32)) -> u32 {
+        a + b
+    }
+    //~^^^ ERROR rust-call ABI is subject to change
+}
+
+fn main() {
+    assert_eq!(Test(1u32, 2u32), 3u32);
+}
diff --git a/tests/ui/feature-gates/feature-gate-unboxed-closures.stderr b/tests/ui/feature-gates/feature-gate-unboxed-closures.stderr
new file mode 100644
index 000000000..a763c28de
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unboxed-closures.stderr
@@ -0,0 +1,30 @@
+error[E0658]: rust-call ABI is subject to change
+  --> $DIR/feature-gate-unboxed-closures.rs:10:12
+   |
+LL |     extern "rust-call" fn call_once(self, (a, b): (u32, u32)) -> u32 {
+   |            ^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0658]: the precise format of `Fn`-family traits' type parameters is subject to change
+  --> $DIR/feature-gate-unboxed-closures.rs:5:6
+   |
+LL | impl FnOnce<(u32, u32)> for Test {
+   |      ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error[E0183]: manual implementations of `FnOnce` are experimental
+  --> $DIR/feature-gate-unboxed-closures.rs:5:6
+   |
+LL | impl FnOnce<(u32, u32)> for Test {
+   |      ^^^^^^^^^^^^^^^^^^ manual implementations of `FnOnce` are experimental
+   |
+   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0183, E0658.
+For more information about an error, try `rustc --explain E0183`.
diff --git a/tests/ui/feature-gates/feature-gate-unix_sigpipe.rs b/tests/ui/feature-gates/feature-gate-unix_sigpipe.rs
new file mode 100644
index 000000000..46dc3f6cc
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unix_sigpipe.rs
@@ -0,0 +1,4 @@
+#![crate_type = "bin"]
+
+#[unix_sigpipe = "inherit"] //~ the `#[unix_sigpipe]` attribute is an experimental feature
+fn main () {}
diff --git a/tests/ui/feature-gates/feature-gate-unix_sigpipe.stderr b/tests/ui/feature-gates/feature-gate-unix_sigpipe.stderr
new file mode 100644
index 000000000..cf3284467
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unix_sigpipe.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[unix_sigpipe]` attribute is an experimental feature
+  --> $DIR/feature-gate-unix_sigpipe.rs:3:1
+   |
+LL | #[unix_sigpipe = "inherit"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #97889 <https://github.com/rust-lang/rust/issues/97889> for more information
+   = help: add `#![feature(unix_sigpipe)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-unsafe_pin_internals.rs b/tests/ui/feature-gates/feature-gate-unsafe_pin_internals.rs
new file mode 100644
index 000000000..0680d2344
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unsafe_pin_internals.rs
@@ -0,0 +1,17 @@
+// edition:2018
+#![forbid(incomplete_features, unsafe_code)]
+#![feature(unsafe_pin_internals)]
+//~^ ERROR the feature `unsafe_pin_internals` is incomplete and may not be safe to use
+
+use core::{marker::PhantomPinned, pin::Pin};
+
+/// The `unsafe_pin_internals` is indeed unsound.
+fn non_unsafe_pin_new_unchecked<T>(pointer: &mut T) -> Pin<&mut T> {
+    Pin { pointer }
+}
+
+fn main() {
+    let mut self_referential = PhantomPinned;
+    let _: Pin<&mut PhantomPinned> = non_unsafe_pin_new_unchecked(&mut self_referential);
+    core::mem::forget(self_referential); // move and disable drop glue!
+}
diff --git a/tests/ui/feature-gates/feature-gate-unsafe_pin_internals.stderr b/tests/ui/feature-gates/feature-gate-unsafe_pin_internals.stderr
new file mode 100644
index 000000000..4d0c931b4
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unsafe_pin_internals.stderr
@@ -0,0 +1,14 @@
+error: the feature `unsafe_pin_internals` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/feature-gate-unsafe_pin_internals.rs:3:12
+   |
+LL | #![feature(unsafe_pin_internals)]
+   |            ^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/feature-gate-unsafe_pin_internals.rs:2:11
+   |
+LL | #![forbid(incomplete_features, unsafe_code)]
+   |           ^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/tests/ui/feature-gates/feature-gate-unsized_fn_params.rs b/tests/ui/feature-gates/feature-gate-unsized_fn_params.rs
new file mode 100644
index 000000000..c04e57843
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unsized_fn_params.rs
@@ -0,0 +1,30 @@
+#![allow(unused, bare_trait_objects)]
+#[repr(align(256))]
+struct A {
+    v: u8,
+}
+
+trait Foo {
+    fn foo(&self);
+}
+
+impl Foo for A {
+    fn foo(&self) {
+        assert_eq!(self as *const A as usize % 256, 0);
+    }
+}
+
+fn foo(x: dyn Foo) { //~ ERROR [E0277]
+    x.foo()
+}
+
+fn bar(x: Foo) { //~ ERROR [E0277]
+    x.foo()
+}
+
+fn qux(_: [()]) {} //~ ERROR [E0277]
+
+fn main() {
+    let x: Box<dyn Foo> = Box::new(A { v: 22 });
+    foo(*x); //~ ERROR [E0277]
+}
diff --git a/tests/ui/feature-gates/feature-gate-unsized_fn_params.stderr b/tests/ui/feature-gates/feature-gate-unsized_fn_params.stderr
new file mode 100644
index 000000000..92c713926
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unsized_fn_params.stderr
@@ -0,0 +1,60 @@
+error[E0277]: the size for values of type `(dyn Foo + 'static)` cannot be known at compilation time
+  --> $DIR/feature-gate-unsized_fn_params.rs:17:8
+   |
+LL | fn foo(x: dyn Foo) {
+   |        ^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `(dyn Foo + 'static)`
+   = help: unsized fn params are gated as an unstable feature
+help: you can use `impl Trait` as the argument type
+   |
+LL | fn foo(x: impl Foo) {
+   |           ~~~~
+help: function arguments must have a statically known size, borrowed types always have a known size
+   |
+LL | fn foo(x: &dyn Foo) {
+   |           +
+
+error[E0277]: the size for values of type `(dyn Foo + 'static)` cannot be known at compilation time
+  --> $DIR/feature-gate-unsized_fn_params.rs:21:8
+   |
+LL | fn bar(x: Foo) {
+   |        ^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `(dyn Foo + 'static)`
+   = help: unsized fn params are gated as an unstable feature
+help: you can use `impl Trait` as the argument type
+   |
+LL | fn bar(x: impl Foo) {
+   |           ++++
+help: function arguments must have a statically known size, borrowed types always have a known size
+   |
+LL | fn bar(x: &Foo) {
+   |           +
+
+error[E0277]: the size for values of type `[()]` cannot be known at compilation time
+  --> $DIR/feature-gate-unsized_fn_params.rs:25:8
+   |
+LL | fn qux(_: [()]) {}
+   |        ^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `[()]`
+   = help: unsized fn params are gated as an unstable feature
+help: function arguments must have a statically known size, borrowed types always have a known size
+   |
+LL | fn qux(_: &[()]) {}
+   |           +
+
+error[E0277]: the size for values of type `(dyn Foo + 'static)` cannot be known at compilation time
+  --> $DIR/feature-gate-unsized_fn_params.rs:29:9
+   |
+LL |     foo(*x);
+   |         ^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `(dyn Foo + 'static)`
+   = note: all function arguments must have a statically known size
+   = help: unsized fn params are gated as an unstable feature
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/feature-gates/feature-gate-unsized_locals.rs b/tests/ui/feature-gates/feature-gate-unsized_locals.rs
new file mode 100644
index 000000000..3686e7b37
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unsized_locals.rs
@@ -0,0 +1,5 @@
+fn f(f: dyn FnOnce()) {}
+//~^ ERROR E0277
+
+fn main() {
+}
diff --git a/tests/ui/feature-gates/feature-gate-unsized_locals.stderr b/tests/ui/feature-gates/feature-gate-unsized_locals.stderr
new file mode 100644
index 000000000..9aeeb88cf
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unsized_locals.stderr
@@ -0,0 +1,20 @@
+error[E0277]: the size for values of type `(dyn FnOnce() + 'static)` cannot be known at compilation time
+  --> $DIR/feature-gate-unsized_locals.rs:1:6
+   |
+LL | fn f(f: dyn FnOnce()) {}
+   |      ^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `(dyn FnOnce() + 'static)`
+   = help: unsized fn params are gated as an unstable feature
+help: you can use `impl Trait` as the argument type
+   |
+LL | fn f(f: impl FnOnce()) {}
+   |         ~~~~
+help: function arguments must have a statically known size, borrowed types always have a known size
+   |
+LL | fn f(f: &dyn FnOnce()) {}
+   |         +
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/feature-gates/feature-gate-unsized_tuple_coercion.rs b/tests/ui/feature-gates/feature-gate-unsized_tuple_coercion.rs
new file mode 100644
index 000000000..c3d62a231
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unsized_tuple_coercion.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let _ : &(dyn Send,) = &((),);
+    //~^ ERROR unsized tuple coercion is not stable enough
+}
diff --git a/tests/ui/feature-gates/feature-gate-unsized_tuple_coercion.stderr b/tests/ui/feature-gates/feature-gate-unsized_tuple_coercion.stderr
new file mode 100644
index 000000000..bea6cee0a
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-unsized_tuple_coercion.stderr
@@ -0,0 +1,12 @@
+error[E0658]: unsized tuple coercion is not stable enough for use and is subject to change
+  --> $DIR/feature-gate-unsized_tuple_coercion.rs:2:28
+   |
+LL |     let _ : &(dyn Send,) = &((),);
+   |                            ^^^^^^
+   |
+   = note: see issue #42877 <https://github.com/rust-lang/rust/issues/42877> for more information
+   = help: add `#![feature(unsized_tuple_coercion)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-used_with_arg.rs b/tests/ui/feature-gates/feature-gate-used_with_arg.rs
new file mode 100644
index 000000000..1c8f01bde
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-used_with_arg.rs
@@ -0,0 +1,7 @@
+#[used(linker)] //~ ERROR `#[used(linker)]` is currently unstable
+static mut USED_LINKER: [usize; 1] = [0];
+
+#[used(compiler)] //~ ERROR `#[used(compiler)]` is currently unstable
+static mut USED_COMPILER: [usize; 1] = [0];
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-used_with_arg.stderr b/tests/ui/feature-gates/feature-gate-used_with_arg.stderr
new file mode 100644
index 000000000..d115bf4e3
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-used_with_arg.stderr
@@ -0,0 +1,21 @@
+error[E0658]: `#[used(linker)]` is currently unstable
+  --> $DIR/feature-gate-used_with_arg.rs:1:1
+   |
+LL | #[used(linker)]
+   | ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #93798 <https://github.com/rust-lang/rust/issues/93798> for more information
+   = help: add `#![feature(used_with_arg)]` to the crate attributes to enable
+
+error[E0658]: `#[used(compiler)]` is currently unstable
+  --> $DIR/feature-gate-used_with_arg.rs:4:1
+   |
+LL | #[used(compiler)]
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #93798 <https://github.com/rust-lang/rust/issues/93798> for more information
+   = help: add `#![feature(used_with_arg)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-vectorcall.rs b/tests/ui/feature-gates/feature-gate-vectorcall.rs
new file mode 100644
index 000000000..5a6c6d288
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-vectorcall.rs
@@ -0,0 +1,31 @@
+// gate-test-abi_vectorcall
+// needs-llvm-components: x86
+// compile-flags: --target=i686-pc-windows-msvc --crate-type=rlib
+#![no_core]
+#![feature(no_core, lang_items)]
+#[lang="sized"]
+trait Sized { }
+
+// Test that the "vectorcall-unwind" ABI is feature-gated, and cannot be used when
+// the `c_unwind` feature gate is not used.
+
+extern "vectorcall" fn f() {} //~ ERROR vectorcall is experimental
+
+trait T {
+    extern "vectorcall" fn m(); //~ ERROR vectorcall is experimental
+
+    extern "vectorcall" fn dm() {} //~ ERROR vectorcall is experimental
+}
+
+struct S;
+impl T for S {
+    extern "vectorcall" fn m() {} //~ ERROR vectorcall is experimental
+}
+
+impl S {
+    extern "vectorcall" fn im() {} //~ ERROR vectorcall is experimental
+}
+
+type TA = extern "vectorcall" fn(); //~ ERROR vectorcall is experimental
+
+extern "vectorcall" {} //~ ERROR vectorcall is experimental
diff --git a/tests/ui/feature-gates/feature-gate-vectorcall.stderr b/tests/ui/feature-gates/feature-gate-vectorcall.stderr
new file mode 100644
index 000000000..55ee76ec3
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-vectorcall.stderr
@@ -0,0 +1,59 @@
+error[E0658]: vectorcall is experimental and subject to change
+  --> $DIR/feature-gate-vectorcall.rs:12:8
+   |
+LL | extern "vectorcall" fn f() {}
+   |        ^^^^^^^^^^^^
+   |
+   = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
+
+error[E0658]: vectorcall is experimental and subject to change
+  --> $DIR/feature-gate-vectorcall.rs:15:12
+   |
+LL |     extern "vectorcall" fn m();
+   |            ^^^^^^^^^^^^
+   |
+   = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
+
+error[E0658]: vectorcall is experimental and subject to change
+  --> $DIR/feature-gate-vectorcall.rs:17:12
+   |
+LL |     extern "vectorcall" fn dm() {}
+   |            ^^^^^^^^^^^^
+   |
+   = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
+
+error[E0658]: vectorcall is experimental and subject to change
+  --> $DIR/feature-gate-vectorcall.rs:22:12
+   |
+LL |     extern "vectorcall" fn m() {}
+   |            ^^^^^^^^^^^^
+   |
+   = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
+
+error[E0658]: vectorcall is experimental and subject to change
+  --> $DIR/feature-gate-vectorcall.rs:26:12
+   |
+LL |     extern "vectorcall" fn im() {}
+   |            ^^^^^^^^^^^^
+   |
+   = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
+
+error[E0658]: vectorcall is experimental and subject to change
+  --> $DIR/feature-gate-vectorcall.rs:29:18
+   |
+LL | type TA = extern "vectorcall" fn();
+   |                  ^^^^^^^^^^^^
+   |
+   = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
+
+error[E0658]: vectorcall is experimental and subject to change
+  --> $DIR/feature-gate-vectorcall.rs:31:8
+   |
+LL | extern "vectorcall" {}
+   |        ^^^^^^^^^^^^
+   |
+   = help: add `#![feature(abi_vectorcall)]` to the crate attributes to enable
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-wasm_abi.rs b/tests/ui/feature-gates/feature-gate-wasm_abi.rs
new file mode 100644
index 000000000..222c88daf
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-wasm_abi.rs
@@ -0,0 +1,26 @@
+// needs-llvm-components: webassembly
+// compile-flags: --target=wasm32-unknown-unknown --crate-type=rlib
+#![no_core]
+#![feature(no_core, lang_items)]
+#[lang="sized"]
+trait Sized { }
+
+extern "wasm" fn fu() {} //~ ERROR wasm ABI is experimental
+
+trait T {
+    extern "wasm" fn mu(); //~ ERROR wasm ABI is experimental
+    extern "wasm" fn dmu() {} //~ ERROR wasm ABI is experimental
+}
+
+struct S;
+impl T for S {
+    extern "wasm" fn mu() {} //~ ERROR wasm ABI is experimental
+}
+
+impl S {
+    extern "wasm" fn imu() {} //~ ERROR wasm ABI is experimental
+}
+
+type TAU = extern "wasm" fn(); //~ ERROR wasm ABI is experimental
+
+extern "wasm" {} //~ ERROR wasm ABI is experimental
diff --git a/tests/ui/feature-gates/feature-gate-wasm_abi.stderr b/tests/ui/feature-gates/feature-gate-wasm_abi.stderr
new file mode 100644
index 000000000..0140002e3
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-wasm_abi.stderr
@@ -0,0 +1,66 @@
+error[E0658]: wasm ABI is experimental and subject to change
+  --> $DIR/feature-gate-wasm_abi.rs:8:8
+   |
+LL | extern "wasm" fn fu() {}
+   |        ^^^^^^
+   |
+   = note: see issue #83788 <https://github.com/rust-lang/rust/issues/83788> for more information
+   = help: add `#![feature(wasm_abi)]` to the crate attributes to enable
+
+error[E0658]: wasm ABI is experimental and subject to change
+  --> $DIR/feature-gate-wasm_abi.rs:11:12
+   |
+LL |     extern "wasm" fn mu();
+   |            ^^^^^^
+   |
+   = note: see issue #83788 <https://github.com/rust-lang/rust/issues/83788> for more information
+   = help: add `#![feature(wasm_abi)]` to the crate attributes to enable
+
+error[E0658]: wasm ABI is experimental and subject to change
+  --> $DIR/feature-gate-wasm_abi.rs:12:12
+   |
+LL |     extern "wasm" fn dmu() {}
+   |            ^^^^^^
+   |
+   = note: see issue #83788 <https://github.com/rust-lang/rust/issues/83788> for more information
+   = help: add `#![feature(wasm_abi)]` to the crate attributes to enable
+
+error[E0658]: wasm ABI is experimental and subject to change
+  --> $DIR/feature-gate-wasm_abi.rs:17:12
+   |
+LL |     extern "wasm" fn mu() {}
+   |            ^^^^^^
+   |
+   = note: see issue #83788 <https://github.com/rust-lang/rust/issues/83788> for more information
+   = help: add `#![feature(wasm_abi)]` to the crate attributes to enable
+
+error[E0658]: wasm ABI is experimental and subject to change
+  --> $DIR/feature-gate-wasm_abi.rs:21:12
+   |
+LL |     extern "wasm" fn imu() {}
+   |            ^^^^^^
+   |
+   = note: see issue #83788 <https://github.com/rust-lang/rust/issues/83788> for more information
+   = help: add `#![feature(wasm_abi)]` to the crate attributes to enable
+
+error[E0658]: wasm ABI is experimental and subject to change
+  --> $DIR/feature-gate-wasm_abi.rs:24:19
+   |
+LL | type TAU = extern "wasm" fn();
+   |                   ^^^^^^
+   |
+   = note: see issue #83788 <https://github.com/rust-lang/rust/issues/83788> for more information
+   = help: add `#![feature(wasm_abi)]` to the crate attributes to enable
+
+error[E0658]: wasm ABI is experimental and subject to change
+  --> $DIR/feature-gate-wasm_abi.rs:26:8
+   |
+LL | extern "wasm" {}
+   |        ^^^^^^
+   |
+   = note: see issue #83788 <https://github.com/rust-lang/rust/issues/83788> for more information
+   = help: add `#![feature(wasm_abi)]` to the crate attributes to enable
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-with_negative_coherence.rs b/tests/ui/feature-gates/feature-gate-with_negative_coherence.rs
new file mode 100644
index 000000000..d1d0a6a90
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-with_negative_coherence.rs
@@ -0,0 +1,8 @@
+trait Foo { }
+
+impl<T: std::ops::DerefMut> Foo for T { }
+
+impl<T> Foo for &T { }
+//~^ ERROR conflicting implementations of trait `Foo` for type `&_` [E0119]
+
+fn main() { }
diff --git a/tests/ui/feature-gates/feature-gate-with_negative_coherence.stderr b/tests/ui/feature-gates/feature-gate-with_negative_coherence.stderr
new file mode 100644
index 000000000..d4c201b5d
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-with_negative_coherence.stderr
@@ -0,0 +1,12 @@
+error[E0119]: conflicting implementations of trait `Foo` for type `&_`
+  --> $DIR/feature-gate-with_negative_coherence.rs:5:1
+   |
+LL | impl<T: std::ops::DerefMut> Foo for T { }
+   | ------------------------------------- first implementation here
+LL |
+LL | impl<T> Foo for &T { }
+   | ^^^^^^^^^^^^^^^^^^ conflicting implementation for `&_`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0119`.
diff --git a/tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.rs b/tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.rs
new file mode 100644
index 000000000..a33bd3450
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.rs
@@ -0,0 +1,19 @@
+// compile-flags: --edition 2021
+
+pub fn demo() -> Option<i32> {
+    #[cfg(nope)]
+    {
+        do yeet //~ ERROR `do yeet` expression is experimental
+    }
+
+    Some(1)
+}
+
+#[cfg(nope)]
+pub fn alternative() -> Result<(), String> {
+    do yeet "hello"; //~ ERROR `do yeet` expression is experimental
+}
+
+fn main() {
+    demo();
+}
diff --git a/tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.stderr b/tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.stderr
new file mode 100644
index 000000000..f90c379bd
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.stderr
@@ -0,0 +1,21 @@
+error[E0658]: `do yeet` expression is experimental
+  --> $DIR/feature-gate-yeet_expr-in-cfg.rs:6:9
+   |
+LL |         do yeet
+   |         ^^^^^^^
+   |
+   = note: see issue #96373 <https://github.com/rust-lang/rust/issues/96373> for more information
+   = help: add `#![feature(yeet_expr)]` to the crate attributes to enable
+
+error[E0658]: `do yeet` expression is experimental
+  --> $DIR/feature-gate-yeet_expr-in-cfg.rs:14:5
+   |
+LL |     do yeet "hello";
+   |     ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #96373 <https://github.com/rust-lang/rust/issues/96373> for more information
+   = help: add `#![feature(yeet_expr)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gate-yeet_expr.rs b/tests/ui/feature-gates/feature-gate-yeet_expr.rs
new file mode 100644
index 000000000..978a84cf6
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-yeet_expr.rs
@@ -0,0 +1,9 @@
+// compile-flags: --edition 2018
+
+pub fn demo() -> Option<i32> {
+    do yeet //~ ERROR `do yeet` expression is experimental
+}
+
+pub fn main() -> Result<(), String> {
+    do yeet "hello"; //~ ERROR `do yeet` expression is experimental
+}
diff --git a/tests/ui/feature-gates/feature-gate-yeet_expr.stderr b/tests/ui/feature-gates/feature-gate-yeet_expr.stderr
new file mode 100644
index 000000000..8d1b92370
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-yeet_expr.stderr
@@ -0,0 +1,21 @@
+error[E0658]: `do yeet` expression is experimental
+  --> $DIR/feature-gate-yeet_expr.rs:4:5
+   |
+LL |     do yeet
+   |     ^^^^^^^
+   |
+   = note: see issue #96373 <https://github.com/rust-lang/rust/issues/96373> for more information
+   = help: add `#![feature(yeet_expr)]` to the crate attributes to enable
+
+error[E0658]: `do yeet` expression is experimental
+  --> $DIR/feature-gate-yeet_expr.rs:8:5
+   |
+LL |     do yeet "hello";
+   |     ^^^^^^^^^^^^^^^
+   |
+   = note: see issue #96373 <https://github.com/rust-lang/rust/issues/96373> for more information
+   = help: add `#![feature(yeet_expr)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/feature-gated-feature-in-macro-arg.rs b/tests/ui/feature-gates/feature-gated-feature-in-macro-arg.rs
new file mode 100644
index 000000000..1285cca6b
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gated-feature-in-macro-arg.rs
@@ -0,0 +1,14 @@
+// tests that input to a macro is checked for use of gated features. If this
+// test succeeds due to the acceptance of a feature, pick a new feature to
+// test. Not ideal, but oh well :(
+
+fn main() {
+    let a = &[1, 2, 3];
+    println!("{}", {
+        extern "rust-intrinsic" { //~ ERROR intrinsics are subject to change
+            fn atomic_fence();
+        }
+        atomic_fence();
+        42
+    });
+}
diff --git a/tests/ui/feature-gates/feature-gated-feature-in-macro-arg.stderr b/tests/ui/feature-gates/feature-gated-feature-in-macro-arg.stderr
new file mode 100644
index 000000000..218e02927
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gated-feature-in-macro-arg.stderr
@@ -0,0 +1,11 @@
+error[E0658]: intrinsics are subject to change
+  --> $DIR/feature-gated-feature-in-macro-arg.rs:8:16
+   |
+LL |         extern "rust-intrinsic" {
+   |                ^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(intrinsics)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/gated-bad-feature.rs b/tests/ui/feature-gates/gated-bad-feature.rs
new file mode 100644
index 000000000..51f2db555
--- /dev/null
+++ b/tests/ui/feature-gates/gated-bad-feature.rs
@@ -0,0 +1,10 @@
+#![feature(foo_bar_baz, foo(bar), foo = "baz", foo)]
+//~^ ERROR malformed `feature`
+//~| ERROR malformed `feature`
+//~| ERROR unknown feature `foo`
+//~| ERROR unknown feature `foo_bar_baz`
+#![feature] //~ ERROR malformed `feature` attribute
+#![feature = "foo"] //~ ERROR malformed `feature` attribute
+#![feature(test_removed_feature)] //~ ERROR: feature has been removed
+
+fn main() {}
diff --git a/tests/ui/feature-gates/gated-bad-feature.stderr b/tests/ui/feature-gates/gated-bad-feature.stderr
new file mode 100644
index 000000000..2d01bdf3c
--- /dev/null
+++ b/tests/ui/feature-gates/gated-bad-feature.stderr
@@ -0,0 +1,46 @@
+error[E0556]: malformed `feature` attribute input
+  --> $DIR/gated-bad-feature.rs:1:25
+   |
+LL | #![feature(foo_bar_baz, foo(bar), foo = "baz", foo)]
+   |                         ^^^^^^^^ help: expected just one word: `foo`
+
+error[E0556]: malformed `feature` attribute input
+  --> $DIR/gated-bad-feature.rs:1:35
+   |
+LL | #![feature(foo_bar_baz, foo(bar), foo = "baz", foo)]
+   |                                   ^^^^^^^^^^^ help: expected just one word: `foo`
+
+error[E0557]: feature has been removed
+  --> $DIR/gated-bad-feature.rs:8:12
+   |
+LL | #![feature(test_removed_feature)]
+   |            ^^^^^^^^^^^^^^^^^^^^ feature has been removed
+
+error: malformed `feature` attribute input
+  --> $DIR/gated-bad-feature.rs:6:1
+   |
+LL | #![feature]
+   | ^^^^^^^^^^^ help: must be of the form: `#![feature(name1, name2, ...)]`
+
+error: malformed `feature` attribute input
+  --> $DIR/gated-bad-feature.rs:7:1
+   |
+LL | #![feature = "foo"]
+   | ^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#![feature(name1, name2, ...)]`
+
+error[E0635]: unknown feature `foo_bar_baz`
+  --> $DIR/gated-bad-feature.rs:1:12
+   |
+LL | #![feature(foo_bar_baz, foo(bar), foo = "baz", foo)]
+   |            ^^^^^^^^^^^
+
+error[E0635]: unknown feature `foo`
+  --> $DIR/gated-bad-feature.rs:1:48
+   |
+LL | #![feature(foo_bar_baz, foo(bar), foo = "baz", foo)]
+   |                                                ^^^
+
+error: aborting due to 7 previous errors
+
+Some errors have detailed explanations: E0556, E0557, E0635.
+For more information about an error, try `rustc --explain E0556`.
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-bench.rs b/tests/ui/feature-gates/issue-43106-gating-of-bench.rs
new file mode 100644
index 000000000..796325b79
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-bench.rs
@@ -0,0 +1,10 @@
+// The non-crate level cases are in issue-43106-gating-of-builtin-attrs.rs.
+// See issue-12997-1.rs and issue-12997-2.rs to see how `#[bench]` is
+// handled in "weird places" when `--test` is passed.
+
+#![feature(custom_inner_attributes)]
+
+#![bench                   = "4100"]
+//~^ ERROR cannot determine resolution for the attribute macro `bench`
+//~^^ ERROR `bench` attribute cannot be used at crate level
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-bench.stderr b/tests/ui/feature-gates/issue-43106-gating-of-bench.stderr
new file mode 100644
index 000000000..6b3322119
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-bench.stderr
@@ -0,0 +1,21 @@
+error: cannot determine resolution for the attribute macro `bench`
+  --> $DIR/issue-43106-gating-of-bench.rs:7:4
+   |
+LL | #![bench                   = "4100"]
+   |    ^^^^^
+   |
+   = note: import resolution is stuck, try simplifying macro imports
+
+error: `bench` attribute cannot be used at crate level
+  --> $DIR/issue-43106-gating-of-bench.rs:7:1
+   |
+LL | #![bench                   = "4100"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[bench                   = "4100"]
+   |
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.rs b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.rs
new file mode 100644
index 000000000..1fe133ac2
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.rs
@@ -0,0 +1,160 @@
+//~ NOTE: not an `extern crate` item
+//~^ NOTE: not a free function, impl method or static
+//~^^ NOTE: not a function or closure
+// This is testing whether various builtin attributes signals an
+// error or warning when put in "weird" places.
+//
+// (This file sits on its own because it actually signals an error,
+// which would mess up the treatment of other cases in
+// issue-43106-gating-of-builtin-attrs.rs)
+
+
+#![macro_export]
+//~^ ERROR: `macro_export` attribute cannot be used at crate level
+#![rustc_main] //~ ERROR: the `#[rustc_main]` attribute is used internally to specify
+//~^ ERROR: `rustc_main` attribute cannot be used at crate level
+#![start]
+//~^ ERROR: `start` attribute cannot be used at crate level
+#![repr()]
+//~^ ERROR: `repr` attribute cannot be used at crate level
+#![path = "3800"]
+//~^ ERROR: `path` attribute cannot be used at crate level
+#![automatically_derived]
+//~^ ERROR: `automatically_derived` attribute cannot be used at crate level
+#![no_mangle]
+#![no_link]
+//~^ ERROR: attribute should be applied to an `extern crate` item
+#![export_name = "2200"]
+//~^ ERROR: attribute should be applied to a free function, impl method or static
+#![inline]
+//~^ ERROR: attribute should be applied to function or closure
+#[inline]
+//~^ ERROR attribute should be applied to function or closure
+mod inline {
+    //~^ NOTE not a function or closure
+
+    mod inner { #![inline] }
+    //~^ ERROR attribute should be applied to function or closure
+    //~| NOTE not a function or closure
+
+    #[inline = "2100"] fn f() { }
+    //~^ ERROR attribute must be of the form
+    //~| WARN this was previously accepted
+    //~| NOTE #[deny(ill_formed_attribute_input)]` on by default
+    //~| NOTE for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>
+
+    #[inline] struct S;
+    //~^ ERROR attribute should be applied to function or closure
+    //~| NOTE not a function or closure
+
+    #[inline] type T = S;
+    //~^ ERROR attribute should be applied to function or closure
+    //~| NOTE not a function or closure
+
+    #[inline] impl S { }
+    //~^ ERROR attribute should be applied to function or closure
+    //~| NOTE not a function or closure
+}
+
+#[no_link]
+//~^ ERROR attribute should be applied to an `extern crate` item
+mod no_link {
+    //~^ NOTE not an `extern crate` item
+
+    mod inner { #![no_link] }
+    //~^ ERROR attribute should be applied to an `extern crate` item
+    //~| NOTE not an `extern crate` item
+
+    #[no_link] fn f() { }
+    //~^ ERROR attribute should be applied to an `extern crate` item
+    //~| NOTE not an `extern crate` item
+
+    #[no_link] struct S;
+    //~^ ERROR attribute should be applied to an `extern crate` item
+    //~| NOTE not an `extern crate` item
+
+    #[no_link]type T = S;
+    //~^ ERROR attribute should be applied to an `extern crate` item
+    //~| NOTE not an `extern crate` item
+
+    #[no_link] impl S { }
+    //~^ ERROR attribute should be applied to an `extern crate` item
+    //~| NOTE not an `extern crate` item
+}
+
+#[export_name = "2200"]
+//~^ ERROR attribute should be applied to a free function, impl method or static
+mod export_name {
+    //~^ NOTE not a free function, impl method or static
+
+    mod inner { #![export_name="2200"] }
+    //~^ ERROR attribute should be applied to a free function, impl method or static
+    //~| NOTE not a free function, impl method or static
+
+    #[export_name = "2200"] fn f() { }
+
+    #[export_name = "2200"] struct S;
+    //~^ ERROR attribute should be applied to a free function, impl method or static
+    //~| NOTE not a free function, impl method or static
+
+    #[export_name = "2200"] type T = S;
+    //~^ ERROR attribute should be applied to a free function, impl method or static
+    //~| NOTE not a free function, impl method or static
+
+    #[export_name = "2200"] impl S { }
+    //~^ ERROR attribute should be applied to a free function, impl method or static
+    //~| NOTE not a free function, impl method or static
+
+    trait Tr {
+        #[export_name = "2200"] fn foo();
+        //~^ ERROR attribute should be applied to a free function, impl method or static
+        //~| NOTE not a free function, impl method or static
+
+        #[export_name = "2200"] fn bar() {}
+        //~^ ERROR attribute should be applied to a free function, impl method or static
+        //~| NOTE not a free function, impl method or static
+    }
+}
+
+#[start]
+//~^ ERROR: `start` attribute can only be used on functions
+mod start {
+    mod inner { #![start] }
+    //~^ ERROR: `start` attribute can only be used on functions
+
+    // for `fn f()` case, see feature-gate-start.rs
+
+    #[start] struct S;
+    //~^ ERROR: `start` attribute can only be used on functions
+
+    #[start] type T = S;
+    //~^ ERROR: `start` attribute can only be used on functions
+
+    #[start] impl S { }
+    //~^ ERROR: `start` attribute can only be used on functions
+}
+
+#[repr(C)]
+//~^ ERROR: attribute should be applied to a struct, enum, or union
+mod repr {
+//~^ NOTE not a struct, enum, or union
+    mod inner { #![repr(C)] }
+    //~^ ERROR: attribute should be applied to a struct, enum, or union
+    //~| NOTE not a struct, enum, or union
+
+    #[repr(C)] fn f() { }
+    //~^ ERROR: attribute should be applied to a struct, enum, or union
+    //~| NOTE not a struct, enum, or union
+
+    struct S;
+
+    #[repr(C)] type T = S;
+    //~^ ERROR: attribute should be applied to a struct, enum, or union
+    //~| NOTE not a struct, enum, or union
+
+    #[repr(C)] impl S { }
+    //~^ ERROR: attribute should be applied to a struct, enum, or union
+    //~| NOTE not a struct, enum, or union
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr
new file mode 100644
index 000000000..787670404
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr
@@ -0,0 +1,310 @@
+error[E0658]: the `#[rustc_main]` attribute is used internally to specify test entry point function
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:14:1
+   |
+LL | #![rustc_main]
+   | ^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+
+error: attribute must be of the form `#[inline]` or `#[inline(always|never)]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:40:5
+   |
+LL |     #[inline = "2100"] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #57571 <https://github.com/rust-lang/rust/issues/57571>
+   = note: `#[deny(ill_formed_attribute_input)]` on by default
+
+error: `start` attribute can only be used on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:119:1
+   |
+LL | #[start]
+   | ^^^^^^^^
+
+error: `start` attribute can only be used on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:122:17
+   |
+LL |     mod inner { #![start] }
+   |                 ^^^^^^^^^
+
+error: `start` attribute can only be used on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:127:5
+   |
+LL |     #[start] struct S;
+   |     ^^^^^^^^
+
+error: `start` attribute can only be used on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:130:5
+   |
+LL |     #[start] type T = S;
+   |     ^^^^^^^^
+
+error: `start` attribute can only be used on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:133:5
+   |
+LL |     #[start] impl S { }
+   |     ^^^^^^^^
+
+error[E0518]: attribute should be applied to function or closure
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:31:1
+   |
+LL |   #[inline]
+   |   ^^^^^^^^^
+LL |
+LL | / mod inline {
+LL | |
+LL | |
+LL | |     mod inner { #![inline] }
+...  |
+LL | |
+LL | | }
+   | |_- not a function or closure
+
+error: attribute should be applied to an `extern crate` item
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:59:1
+   |
+LL |   #[no_link]
+   |   ^^^^^^^^^^
+LL |
+LL | / mod no_link {
+LL | |
+LL | |
+LL | |     mod inner { #![no_link] }
+...  |
+LL | |
+LL | | }
+   | |_- not an `extern crate` item
+
+error: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:85:1
+   |
+LL |   #[export_name = "2200"]
+   |   ^^^^^^^^^^^^^^^^^^^^^^^
+LL |
+LL | / mod export_name {
+LL | |
+LL | |
+LL | |     mod inner { #![export_name="2200"] }
+...  |
+LL | |     }
+LL | | }
+   | |_- not a free function, impl method or static
+
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:137:8
+   |
+LL |   #[repr(C)]
+   |          ^
+LL |
+LL | / mod repr {
+LL | |
+LL | |     mod inner { #![repr(C)] }
+LL | |
+...  |
+LL | |
+LL | | }
+   | |_- not a struct, enum, or union
+
+error: attribute should be applied to an `extern crate` item
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:25:1
+   |
+LL | #![no_link]
+   | ^^^^^^^^^^^ not an `extern crate` item
+
+error: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:27:1
+   |
+LL | #![export_name = "2200"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^ not a free function, impl method or static
+
+error[E0518]: attribute should be applied to function or closure
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:29:1
+   |
+LL | #![inline]
+   | ^^^^^^^^^^ not a function or closure
+
+error: `macro_export` attribute cannot be used at crate level
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:12:1
+   |
+LL | #![macro_export]
+   | ^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[macro_export]
+   |
+
+error: `rustc_main` attribute cannot be used at crate level
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:14:1
+   |
+LL | #![rustc_main]
+   | ^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[rustc_main]
+   | ~~~~~~~~~~~~~
+
+error: `start` attribute cannot be used at crate level
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:16:1
+   |
+LL | #![start]
+   | ^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[start]
+   |
+
+error: `repr` attribute cannot be used at crate level
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:18:1
+   |
+LL | #![repr()]
+   | ^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[repr()]
+   |
+
+error: `path` attribute cannot be used at crate level
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:20:1
+   |
+LL | #![path = "3800"]
+   | ^^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[path = "3800"]
+   |
+
+error: `automatically_derived` attribute cannot be used at crate level
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:22:1
+   |
+LL | #![automatically_derived]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[automatically_derived]
+   |
+
+error[E0518]: attribute should be applied to function or closure
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:36:17
+   |
+LL |     mod inner { #![inline] }
+   |     ------------^^^^^^^^^^-- not a function or closure
+
+error[E0518]: attribute should be applied to function or closure
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:46:5
+   |
+LL |     #[inline] struct S;
+   |     ^^^^^^^^^ --------- not a function or closure
+
+error[E0518]: attribute should be applied to function or closure
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:50:5
+   |
+LL |     #[inline] type T = S;
+   |     ^^^^^^^^^ ----------- not a function or closure
+
+error[E0518]: attribute should be applied to function or closure
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:54:5
+   |
+LL |     #[inline] impl S { }
+   |     ^^^^^^^^^ ---------- not a function or closure
+
+error: attribute should be applied to an `extern crate` item
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:64:17
+   |
+LL |     mod inner { #![no_link] }
+   |     ------------^^^^^^^^^^^-- not an `extern crate` item
+
+error: attribute should be applied to an `extern crate` item
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:68:5
+   |
+LL |     #[no_link] fn f() { }
+   |     ^^^^^^^^^^ ---------- not an `extern crate` item
+
+error: attribute should be applied to an `extern crate` item
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:72:5
+   |
+LL |     #[no_link] struct S;
+   |     ^^^^^^^^^^ --------- not an `extern crate` item
+
+error: attribute should be applied to an `extern crate` item
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:76:5
+   |
+LL |     #[no_link]type T = S;
+   |     ^^^^^^^^^^----------- not an `extern crate` item
+
+error: attribute should be applied to an `extern crate` item
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:80:5
+   |
+LL |     #[no_link] impl S { }
+   |     ^^^^^^^^^^ ---------- not an `extern crate` item
+
+error: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:90:17
+   |
+LL |     mod inner { #![export_name="2200"] }
+   |     ------------^^^^^^^^^^^^^^^^^^^^^^-- not a free function, impl method or static
+
+error: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:96:5
+   |
+LL |     #[export_name = "2200"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^ --------- not a free function, impl method or static
+
+error: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:100:5
+   |
+LL |     #[export_name = "2200"] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^ ----------- not a free function, impl method or static
+
+error: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:104:5
+   |
+LL |     #[export_name = "2200"] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^ ---------- not a free function, impl method or static
+
+error: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:109:9
+   |
+LL |         #[export_name = "2200"] fn foo();
+   |         ^^^^^^^^^^^^^^^^^^^^^^^ --------- not a free function, impl method or static
+
+error: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:113:9
+   |
+LL |         #[export_name = "2200"] fn bar() {}
+   |         ^^^^^^^^^^^^^^^^^^^^^^^ ----------- not a free function, impl method or static
+
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:141:25
+   |
+LL |     mod inner { #![repr(C)] }
+   |     --------------------^---- not a struct, enum, or union
+
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:145:12
+   |
+LL |     #[repr(C)] fn f() { }
+   |            ^   ---------- not a struct, enum, or union
+
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:151:12
+   |
+LL |     #[repr(C)] type T = S;
+   |            ^   ----------- not a struct, enum, or union
+
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:155:12
+   |
+LL |     #[repr(C)] impl S { }
+   |            ^   ---------- not a struct, enum, or union
+
+error: aborting due to 39 previous errors
+
+Some errors have detailed explanations: E0517, E0518, E0658.
+For more information about an error, try `rustc --explain E0517`.
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.rs b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.rs
new file mode 100644
index 000000000..1fa315f3d
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.rs
@@ -0,0 +1,772 @@
+//~ NOTE not a function
+//~| NOTE not a foreign function or static
+//~| NOTE cannot be applied to crates
+//~| NOTE not an `extern` block
+// This test enumerates as many compiler-builtin ungated attributes as
+// possible (that is, all the mutually compatible ones), and checks
+// that we get "expected" (*) warnings for each in the various weird
+// places that users might put them in the syntax.
+//
+// (*): The word "expected" is in quotes above because the cases where
+// warnings are and are not emitted might not match a user's intuition
+// nor the rustc developers' intent. I am really just trying to
+// capture today's behavior in a test, not so that it become enshrined
+// as the absolute behavior going forward, but rather so that we do
+// not change the behavior in the future without even being *aware* of
+// the change when it happens.
+//
+// At the time of authoring, the attributes here are listed in the
+// order that they occur in `librustc_feature`.
+//
+// Any builtin attributes that:
+//
+//  - are not stable, or
+//
+//  - could not be included here covering the same cases as the other
+//    attributes without raising an *error* from rustc (note though
+//    that warnings are of course expected)
+//
+// have their own test case referenced by filename in an inline
+// comment.
+//
+// The test feeds numeric inputs to each attribute that accepts them
+// without error. We do this for two reasons: (1.) to exercise how
+// inputs are handled by each, and (2.) to ease searching for related
+// occurrences in the source text.
+
+// check-pass
+
+#![feature(test)]
+#![warn(unused_attributes, unknown_lints)]
+//~^ NOTE the lint level is defined here
+//~| NOTE the lint level is defined here
+
+// UNGATED WHITE-LISTED BUILT-IN ATTRIBUTES
+
+#![warn(x5400)] //~ WARN unknown lint: `x5400`
+#![allow(x5300)] //~ WARN unknown lint: `x5300`
+#![forbid(x5200)] //~ WARN unknown lint: `x5200`
+#![deny(x5100)] //~ WARN unknown lint: `x5100`
+#![macro_use] // (allowed if no argument; see issue-43160-gating-of-macro_use.rs)
+// skipping testing of cfg
+// skipping testing of cfg_attr
+#![should_panic] //~ WARN `#[should_panic]` only has an effect
+#![ignore] //~ WARN `#[ignore]` only has an effect on functions
+#![no_implicit_prelude]
+#![reexport_test_harness_main = "2900"]
+// see gated-link-args.rs
+// see issue-43106-gating-of-macro_escape.rs for crate-level; but non crate-level is below at "2700"
+// (cannot easily test gating of crate-level #[no_std]; but non crate-level is below at "2600")
+#![proc_macro_derive()] //~ WARN `#[proc_macro_derive]` only has an effect
+#![doc = "2400"]
+#![cold] //~ WARN attribute should be applied to a function
+//~^ WARN this was previously accepted
+#![link()] //~ WARN attribute should be applied to an `extern` block
+//~^ WARN this was previously accepted
+#![link_name = "1900"]
+//~^ WARN attribute should be applied to a foreign function
+//~^^ WARN this was previously accepted by the compiler
+#![link_section = "1800"]
+//~^ WARN attribute should be applied to a function or static
+//~^^ WARN this was previously accepted by the compiler
+#![must_use]
+//~^ WARN `#[must_use]` has no effect
+// see issue-43106-gating-of-stable.rs
+// see issue-43106-gating-of-unstable.rs
+// see issue-43106-gating-of-deprecated.rs
+#![windows_subsystem = "windows"]
+
+// UNGATED CRATE-LEVEL BUILT-IN ATTRIBUTES
+
+#![crate_name = "0900"]
+#![crate_type = "bin"] // cannot pass "0800" here
+
+#![crate_id = "10"]
+//~^ WARN use of deprecated attribute
+//~| HELP remove this attribute
+//~| NOTE `#[warn(deprecated)]` on by default
+
+// FIXME(#44232) we should warn that this isn't used.
+#![feature(rust1)]
+//~^ WARN no longer requires an attribute to enable
+//~| NOTE `#[warn(stable_features)]` on by default
+
+#![no_start]
+//~^ WARN use of deprecated attribute
+//~| HELP remove this attribute
+
+// (cannot easily gating state of crate-level #[no_main]; but non crate-level is below at "0400")
+#![no_builtins]
+#![recursion_limit = "0200"]
+#![type_length_limit = "0100"]
+
+// USES OF BUILT-IN ATTRIBUTES IN OTHER ("UNUSUAL") PLACES
+
+#[warn(x5400)]
+//~^ WARN unknown lint: `x5400`
+mod warn {
+    mod inner { #![warn(x5400)] }
+    //~^ WARN unknown lint: `x5400`
+
+    #[warn(x5400)] fn f() { }
+    //~^ WARN unknown lint: `x5400`
+
+    #[warn(x5400)] struct S;
+    //~^ WARN unknown lint: `x5400`
+
+    #[warn(x5400)] type T = S;
+    //~^ WARN unknown lint: `x5400`
+
+    #[warn(x5400)] impl S { }
+    //~^ WARN unknown lint: `x5400`
+}
+
+#[allow(x5300)]
+//~^ WARN unknown lint: `x5300`
+mod allow {
+    mod inner { #![allow(x5300)] }
+    //~^ WARN unknown lint: `x5300`
+
+    #[allow(x5300)] fn f() { }
+    //~^ WARN unknown lint: `x5300`
+
+    #[allow(x5300)] struct S;
+    //~^ WARN unknown lint: `x5300`
+
+    #[allow(x5300)] type T = S;
+    //~^ WARN unknown lint: `x5300`
+
+    #[allow(x5300)] impl S { }
+    //~^ WARN unknown lint: `x5300`
+}
+
+#[forbid(x5200)]
+//~^ WARN unknown lint: `x5200`
+mod forbid {
+    mod inner { #![forbid(x5200)] }
+    //~^ WARN unknown lint: `x5200`
+
+    #[forbid(x5200)] fn f() { }
+    //~^ WARN unknown lint: `x5200`
+
+    #[forbid(x5200)] struct S;
+    //~^ WARN unknown lint: `x5200`
+
+    #[forbid(x5200)] type T = S;
+    //~^ WARN unknown lint: `x5200`
+
+    #[forbid(x5200)] impl S { }
+    //~^ WARN unknown lint: `x5200`
+}
+
+#[deny(x5100)]
+//~^ WARN unknown lint: `x5100`
+mod deny {
+    mod inner { #![deny(x5100)] }
+    //~^ WARN unknown lint: `x5100`
+
+    #[deny(x5100)] fn f() { }
+    //~^ WARN unknown lint: `x5100`
+
+    #[deny(x5100)] struct S;
+    //~^ WARN unknown lint: `x5100`
+
+    #[deny(x5100)] type T = S;
+    //~^ WARN unknown lint: `x5100`
+
+    #[deny(x5100)] impl S { }
+    //~^ WARN unknown lint: `x5100`
+}
+
+#[macro_use]
+mod macro_use {
+    mod inner { #![macro_use] }
+
+    #[macro_use] fn f() { }
+    //~^ `#[macro_use]` only has an effect
+
+    #[macro_use] struct S;
+    //~^ `#[macro_use]` only has an effect
+
+    #[macro_use] type T = S;
+    //~^ `#[macro_use]` only has an effect
+
+    #[macro_use] impl S { }
+    //~^ `#[macro_use]` only has an effect
+}
+
+#[macro_export]
+//~^ WARN `#[macro_export]` only has an effect on macro definitions
+mod macro_export {
+    mod inner { #![macro_export] }
+    //~^ WARN `#[macro_export]` only has an effect on macro definitions
+
+    #[macro_export] fn f() { }
+    //~^ WARN `#[macro_export]` only has an effect on macro definitions
+
+    #[macro_export] struct S;
+    //~^ WARN `#[macro_export]` only has an effect on macro definitions
+
+    #[macro_export] type T = S;
+    //~^ WARN `#[macro_export]` only has an effect on macro definitions
+
+    #[macro_export] impl S { }
+    //~^ WARN `#[macro_export]` only has an effect on macro definitions
+}
+
+// At time of unit test authorship, if compiling without `--test` then
+// non-crate-level #[test] attributes seem to be ignored.
+
+#[test]
+mod test { mod inner { #![test] }
+
+    fn f() { }
+
+    struct S;
+
+    type T = S;
+
+    impl S { }
+}
+
+// At time of unit test authorship, if compiling without `--test` then
+// non-crate-level #[bench] attributes seem to be ignored.
+
+#[bench]
+mod bench {
+    mod inner { #![bench] }
+
+    #[bench]
+    struct S;
+
+    #[bench]
+    type T = S;
+
+    #[bench]
+    impl S { }
+}
+
+#[path = "3800"]
+mod path {
+    mod inner { #![path="3800"] }
+
+    #[path = "3800"] fn f() { }
+    //~^ WARN `#[path]` only has an effect
+
+    #[path = "3800"]  struct S;
+    //~^ WARN `#[path]` only has an effect
+
+    #[path = "3800"] type T = S;
+    //~^ WARN `#[path]` only has an effect
+
+    #[path = "3800"] impl S { }
+    //~^ WARN `#[path]` only has an effect
+}
+
+#[automatically_derived]
+//~^ WARN `#[automatically_derived]` only has an effect
+mod automatically_derived {
+    mod inner { #![automatically_derived] }
+    //~^ WARN `#[automatically_derived]
+
+    #[automatically_derived] fn f() { }
+    //~^ WARN `#[automatically_derived]
+
+    #[automatically_derived] struct S;
+    //~^ WARN `#[automatically_derived]
+
+    #[automatically_derived] type T = S;
+    //~^ WARN `#[automatically_derived]
+
+    #[automatically_derived] impl S { }
+}
+
+#[no_mangle]
+//~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+mod no_mangle {
+    //~^ NOTE not a free function, impl method or static
+    mod inner { #![no_mangle] }
+    //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a free function, impl method or static
+
+    #[no_mangle] fn f() { }
+
+    #[no_mangle] struct S;
+    //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a free function, impl method or static
+
+    #[no_mangle] type T = S;
+    //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a free function, impl method or static
+
+    #[no_mangle] impl S { }
+    //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a free function, impl method or static
+
+    trait Tr {
+        #[no_mangle] fn foo();
+        //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
+        //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+        //~| NOTE not a free function, impl method or static
+
+        #[no_mangle] fn bar() {}
+        //~^ WARN attribute should be applied to a free function, impl method or static [unused_attributes]
+        //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+        //~| NOTE not a free function, impl method or static
+    }
+}
+
+#[should_panic]
+//~^ WARN `#[should_panic]` only has an effect on
+mod should_panic {
+    mod inner { #![should_panic] }
+    //~^ WARN `#[should_panic]` only has an effect on
+
+    #[should_panic] fn f() { }
+
+    #[should_panic] struct S;
+    //~^ WARN `#[should_panic]` only has an effect on
+
+    #[should_panic] type T = S;
+    //~^ WARN `#[should_panic]` only has an effect on
+
+    #[should_panic] impl S { }
+    //~^ WARN `#[should_panic]` only has an effect on
+}
+
+#[ignore]
+//~^ WARN `#[ignore]` only has an effect on functions
+mod ignore {
+    mod inner { #![ignore] }
+    //~^ WARN `#[ignore]` only has an effect on functions
+
+    #[ignore] fn f() { }
+
+    #[ignore] struct S;
+    //~^ WARN `#[ignore]` only has an effect on functions
+
+    #[ignore] type T = S;
+    //~^ WARN `#[ignore]` only has an effect on functions
+
+    #[ignore] impl S { }
+    //~^ WARN `#[ignore]` only has an effect on functions
+}
+
+#[no_implicit_prelude]
+mod no_implicit_prelude {
+    mod inner { #![no_implicit_prelude] }
+
+    #[no_implicit_prelude] fn f() { }
+    //~^ WARN `#[no_implicit_prelude]` only has an effect
+
+    #[no_implicit_prelude] struct S;
+    //~^ WARN `#[no_implicit_prelude]` only has an effect
+
+    #[no_implicit_prelude] type T = S;
+    //~^ WARN `#[no_implicit_prelude]` only has an effect
+
+    #[no_implicit_prelude] impl S { }
+    //~^ WARN `#[no_implicit_prelude]` only has an effect
+}
+
+#[reexport_test_harness_main = "2900"]
+//~^ WARN crate-level attribute should be
+mod reexport_test_harness_main {
+    mod inner { #![reexport_test_harness_main="2900"] }
+    //~^ WARN crate-level attribute should be
+
+    #[reexport_test_harness_main = "2900"] fn f() { }
+    //~^ WARN crate-level attribute should be
+
+    #[reexport_test_harness_main = "2900"] struct S;
+    //~^ WARN crate-level attribute should be
+
+    #[reexport_test_harness_main = "2900"] type T = S;
+    //~^ WARN crate-level attribute should be
+
+    #[reexport_test_harness_main = "2900"] impl S { }
+    //~^ WARN crate-level attribute should be
+}
+
+// Cannot feed "2700" to `#[macro_escape]` without signaling an error.
+#[macro_escape]
+//~^ WARN `#[macro_escape]` is a deprecated synonym for `#[macro_use]`
+mod macro_escape {
+    mod inner { #![macro_escape] }
+    //~^ WARN `#[macro_escape]` is a deprecated synonym for `#[macro_use]`
+    //~| HELP try an outer attribute: `#[macro_use]`
+
+    #[macro_escape] fn f() { }
+    //~^ WARN `#[macro_escape]` only has an effect
+
+    #[macro_escape] struct S;
+    //~^ WARN `#[macro_escape]` only has an effect
+
+    #[macro_escape] type T = S;
+    //~^ WARN `#[macro_escape]` only has an effect
+
+    #[macro_escape] impl S { }
+    //~^ WARN `#[macro_escape]` only has an effect
+}
+
+#[no_std]
+//~^ WARN crate-level attribute should be an inner attribute
+mod no_std {
+    mod inner { #![no_std] }
+//~^ WARN crate-level attribute should be in the root module
+
+    #[no_std] fn f() { }
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[no_std] struct S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[no_std] type T = S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[no_std] impl S { }
+    //~^ WARN crate-level attribute should be an inner attribute
+}
+
+// At time of authorship, #[proc_macro_derive = "2500"] signals error
+// when it occurs on a mod (apart from crate-level). Therefore it goes
+// into its own file; see issue-43106-gating-of-proc_macro_derive.rs
+
+#[doc = "2400"]
+mod doc {
+    mod inner { #![doc="2400"] }
+
+    #[doc = "2400"] fn f() { }
+
+    #[doc = "2400"] struct S;
+
+    #[doc = "2400"] type T = S;
+
+    #[doc = "2400"] impl S { }
+}
+
+#[cold]
+//~^ WARN attribute should be applied to a function
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+mod cold {
+    //~^ NOTE not a function
+
+    mod inner { #![cold] }
+    //~^ WARN attribute should be applied to a function
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function
+
+    #[cold] fn f() { }
+
+    #[cold] struct S;
+    //~^ WARN attribute should be applied to a function
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function
+
+    #[cold] type T = S;
+    //~^ WARN attribute should be applied to a function
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function
+
+    #[cold] impl S { }
+    //~^ WARN attribute should be applied to a function
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function
+}
+
+#[link_name = "1900"]
+//~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+mod link_name {
+    //~^ NOTE not a foreign function or static
+
+    #[link_name = "1900"]
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| HELP try `#[link(name = "1900")]` instead
+    extern "C" { }
+    //~^ NOTE not a foreign function or static
+
+    mod inner { #![link_name="1900"] }
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a foreign function or static
+
+    #[link_name = "1900"] fn f() { }
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a foreign function or static
+
+    #[link_name = "1900"] struct S;
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a foreign function or static
+
+    #[link_name = "1900"] type T = S;
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a foreign function or static
+
+    #[link_name = "1900"] impl S { }
+    //~^ WARN attribute should be applied to a foreign function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a foreign function or static
+}
+
+#[link_section = "1800"]
+//~^ WARN attribute should be applied to a function or static [unused_attributes]
+//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+mod link_section {
+    //~^ NOTE not a function or static
+
+    mod inner { #![link_section="1800"] }
+    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function or static
+
+    #[link_section = "1800"] fn f() { }
+
+    #[link_section = "1800"] struct S;
+    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function or static
+
+    #[link_section = "1800"] type T = S;
+    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function or static
+
+    #[link_section = "1800"] impl S { }
+    //~^ WARN attribute should be applied to a function or static [unused_attributes]
+    //~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    //~| NOTE not a function or static
+}
+
+
+// Note that this is a `check-pass` test, so it will never invoke the linker.
+
+#[link()]
+//~^ WARN attribute should be applied to an `extern` block
+//~| WARN this was previously accepted
+mod link {
+    //~^ NOTE not an `extern` block
+
+    mod inner { #![link()] }
+    //~^ WARN attribute should be applied to an `extern` block
+    //~| WARN this was previously accepted
+    //~| NOTE not an `extern` block
+
+    #[link()] fn f() { }
+    //~^ WARN attribute should be applied to an `extern` block
+    //~| WARN this was previously accepted
+    //~| NOTE not an `extern` block
+
+    #[link()] struct S;
+    //~^ WARN attribute should be applied to an `extern` block
+    //~| WARN this was previously accepted
+    //~| NOTE not an `extern` block
+
+    #[link()] type T = S;
+    //~^ WARN attribute should be applied to an `extern` block
+    //~| WARN this was previously accepted
+    //~| NOTE not an `extern` block
+
+    #[link()] impl S { }
+    //~^ WARN attribute should be applied to an `extern` block
+    //~| WARN this was previously accepted
+    //~| NOTE not an `extern` block
+
+    #[link()] extern "Rust" {}
+    //~^ WARN attribute should be applied to an `extern` block
+    //~| WARN this was previously accepted
+}
+
+struct StructForDeprecated;
+
+#[deprecated]
+mod deprecated {
+    mod inner { #![deprecated] }
+
+    #[deprecated] fn f() { }
+
+    #[deprecated] struct S1;
+
+    #[deprecated] type T = super::StructForDeprecated;
+
+    #[deprecated] impl super::StructForDeprecated { }
+}
+
+#[must_use] //~ WARN `#[must_use]` has no effect
+mod must_use {
+    mod inner { #![must_use] } //~ WARN `#[must_use]` has no effect
+
+    #[must_use] fn f() { }
+
+    #[must_use] struct S;
+
+    #[must_use] type T = S; //~ WARN `#[must_use]` has no effect
+
+    #[must_use] impl S { } //~ WARN `#[must_use]` has no effect
+}
+
+#[windows_subsystem = "windows"]
+//~^ WARN crate-level attribute should be an inner attribute
+mod windows_subsystem {
+    mod inner { #![windows_subsystem="windows"] }
+    //~^ WARN crate-level attribute should be in the root module
+
+    #[windows_subsystem = "windows"] fn f() { }
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[windows_subsystem = "windows"] struct S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[windows_subsystem = "windows"] type T = S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[windows_subsystem = "windows"] impl S { }
+    //~^ WARN crate-level attribute should be an inner attribute
+}
+
+// BROKEN USES OF CRATE-LEVEL BUILT-IN ATTRIBUTES
+
+#[crate_name = "0900"]
+//~^ WARN crate-level attribute should be an inner attribute
+mod crate_name {
+    mod inner { #![crate_name="0900"] }
+//~^ WARN crate-level attribute should be in the root module
+
+    #[crate_name = "0900"] fn f() { }
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[crate_name = "0900"] struct S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[crate_name = "0900"] type T = S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[crate_name = "0900"] impl S { }
+    //~^ WARN crate-level attribute should be an inner attribute
+}
+
+#[crate_type = "0800"]
+//~^ WARN crate-level attribute should be an inner attribute
+mod crate_type {
+    mod inner { #![crate_type="0800"] }
+//~^ WARN crate-level attribute should be in the root module
+
+    #[crate_type = "0800"] fn f() { }
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[crate_type = "0800"] struct S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[crate_type = "0800"] type T = S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[crate_type = "0800"] impl S { }
+    //~^ WARN crate-level attribute should be an inner attribute
+}
+
+#[feature(x0600)]
+//~^ WARN crate-level attribute should be an inner attribute
+mod feature {
+    mod inner { #![feature(x0600)] }
+//~^ WARN crate-level attribute should be in the root module
+
+    #[feature(x0600)] fn f() { }
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[feature(x0600)] struct S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[feature(x0600)] type T = S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[feature(x0600)] impl S { }
+    //~^ WARN crate-level attribute should be an inner attribute
+}
+
+
+#[no_main]
+//~^ WARN crate-level attribute should be an inner attribute
+mod no_main_1 {
+    mod inner { #![no_main] }
+//~^ WARN crate-level attribute should be in the root module
+
+    #[no_main] fn f() { }
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[no_main] struct S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[no_main] type T = S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[no_main] impl S { }
+    //~^ WARN crate-level attribute should be an inner attribute
+}
+
+#[no_builtins]
+//~^ WARN crate-level attribute should be an inner attribute
+mod no_builtins {
+    mod inner { #![no_builtins] }
+    //~^ WARN crate-level attribute should be in the root module
+
+    #[no_builtins] fn f() { }
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[no_builtins] struct S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[no_builtins] type T = S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[no_builtins] impl S { }
+    //~^ WARN crate-level attribute should be an inner attribute
+}
+
+#[recursion_limit="0200"]
+//~^ WARN crate-level attribute should be an inner attribute
+mod recursion_limit {
+    mod inner { #![recursion_limit="0200"] }
+//~^ WARN crate-level attribute should be in the root module
+
+    #[recursion_limit="0200"] fn f() { }
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[recursion_limit="0200"] struct S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[recursion_limit="0200"] type T = S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[recursion_limit="0200"] impl S { }
+    //~^ WARN crate-level attribute should be an inner attribute
+}
+
+#[type_length_limit="0100"]
+//~^ WARN crate-level attribute should be an inner attribute
+mod type_length_limit {
+    mod inner { #![type_length_limit="0100"] }
+//~^ WARN crate-level attribute should be in the root module
+
+    #[type_length_limit="0100"] fn f() { }
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[type_length_limit="0100"] struct S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[type_length_limit="0100"] type T = S;
+    //~^ WARN crate-level attribute should be an inner attribute
+
+    #[type_length_limit="0100"] impl S { }
+    //~^ WARN crate-level attribute should be an inner attribute
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.stderr b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.stderr
new file mode 100644
index 000000000..300392679
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-builtin-attrs.stderr
@@ -0,0 +1,1181 @@
+warning: `#[macro_escape]` is a deprecated synonym for `#[macro_use]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:400:17
+   |
+LL |     mod inner { #![macro_escape] }
+   |                 ^^^^^^^^^^^^^^^^
+   |
+   = help: try an outer attribute: `#[macro_use]`
+
+warning: `#[macro_escape]` is a deprecated synonym for `#[macro_use]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:397:1
+   |
+LL | #[macro_escape]
+   | ^^^^^^^^^^^^^^^
+
+warning: unknown lint: `x5400`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:46:9
+   |
+LL | #![warn(x5400)]
+   |         ^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:40:28
+   |
+LL | #![warn(unused_attributes, unknown_lints)]
+   |                            ^^^^^^^^^^^^^
+
+warning: unknown lint: `x5300`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:47:10
+   |
+LL | #![allow(x5300)]
+   |          ^^^^^
+
+warning: unknown lint: `x5200`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:48:11
+   |
+LL | #![forbid(x5200)]
+   |           ^^^^^
+
+warning: unknown lint: `x5100`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:49:9
+   |
+LL | #![deny(x5100)]
+   |         ^^^^^
+
+warning: unknown lint: `x5400`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:105:8
+   |
+LL | #[warn(x5400)]
+   |        ^^^^^
+
+warning: unknown lint: `x5400`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:108:25
+   |
+LL |     mod inner { #![warn(x5400)] }
+   |                         ^^^^^
+
+warning: unknown lint: `x5400`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:111:12
+   |
+LL |     #[warn(x5400)] fn f() { }
+   |            ^^^^^
+
+warning: unknown lint: `x5400`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:114:12
+   |
+LL |     #[warn(x5400)] struct S;
+   |            ^^^^^
+
+warning: unknown lint: `x5400`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:117:12
+   |
+LL |     #[warn(x5400)] type T = S;
+   |            ^^^^^
+
+warning: unknown lint: `x5400`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:120:12
+   |
+LL |     #[warn(x5400)] impl S { }
+   |            ^^^^^
+
+warning: unknown lint: `x5300`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:124:9
+   |
+LL | #[allow(x5300)]
+   |         ^^^^^
+
+warning: unknown lint: `x5300`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:127:26
+   |
+LL |     mod inner { #![allow(x5300)] }
+   |                          ^^^^^
+
+warning: unknown lint: `x5300`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:130:13
+   |
+LL |     #[allow(x5300)] fn f() { }
+   |             ^^^^^
+
+warning: unknown lint: `x5300`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:133:13
+   |
+LL |     #[allow(x5300)] struct S;
+   |             ^^^^^
+
+warning: unknown lint: `x5300`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:136:13
+   |
+LL |     #[allow(x5300)] type T = S;
+   |             ^^^^^
+
+warning: unknown lint: `x5300`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:139:13
+   |
+LL |     #[allow(x5300)] impl S { }
+   |             ^^^^^
+
+warning: unknown lint: `x5200`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:143:10
+   |
+LL | #[forbid(x5200)]
+   |          ^^^^^
+
+warning: unknown lint: `x5200`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:146:27
+   |
+LL |     mod inner { #![forbid(x5200)] }
+   |                           ^^^^^
+
+warning: unknown lint: `x5200`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:149:14
+   |
+LL |     #[forbid(x5200)] fn f() { }
+   |              ^^^^^
+
+warning: unknown lint: `x5200`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:152:14
+   |
+LL |     #[forbid(x5200)] struct S;
+   |              ^^^^^
+
+warning: unknown lint: `x5200`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:155:14
+   |
+LL |     #[forbid(x5200)] type T = S;
+   |              ^^^^^
+
+warning: unknown lint: `x5200`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:158:14
+   |
+LL |     #[forbid(x5200)] impl S { }
+   |              ^^^^^
+
+warning: unknown lint: `x5100`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:162:8
+   |
+LL | #[deny(x5100)]
+   |        ^^^^^
+
+warning: unknown lint: `x5100`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:165:25
+   |
+LL |     mod inner { #![deny(x5100)] }
+   |                         ^^^^^
+
+warning: unknown lint: `x5100`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:168:12
+   |
+LL |     #[deny(x5100)] fn f() { }
+   |            ^^^^^
+
+warning: unknown lint: `x5100`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:171:12
+   |
+LL |     #[deny(x5100)] struct S;
+   |            ^^^^^
+
+warning: unknown lint: `x5100`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:174:12
+   |
+LL |     #[deny(x5100)] type T = S;
+   |            ^^^^^
+
+warning: unknown lint: `x5100`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:177:12
+   |
+LL |     #[deny(x5100)] impl S { }
+   |            ^^^^^
+
+warning: use of deprecated attribute `crate_id`: no longer used.
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:84:1
+   |
+LL | #![crate_id = "10"]
+   | ^^^^^^^^^^^^^^^^^^^ help: remove this attribute
+   |
+   = note: `#[warn(deprecated)]` on by default
+
+warning: use of deprecated attribute `no_start`: no longer used.
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:94:1
+   |
+LL | #![no_start]
+   | ^^^^^^^^^^^^ help: remove this attribute
+
+warning: `#[macro_export]` only has an effect on macro definitions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:198:1
+   |
+LL | #[macro_export]
+   | ^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:40:9
+   |
+LL | #![warn(unused_attributes, unknown_lints)]
+   |         ^^^^^^^^^^^^^^^^^
+
+warning: `#[automatically_derived]` only has an effect on implementation blocks
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:266:1
+   |
+LL | #[automatically_derived]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:284:1
+   |
+LL |   #[no_mangle]
+   |   ^^^^^^^^^^^^
+...
+LL | / mod no_mangle {
+LL | |
+LL | |     mod inner { #![no_mangle] }
+LL | |
+...  |
+LL | |     }
+LL | | }
+   | |_- not a free function, impl method or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: `#[should_panic]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:324:1
+   |
+LL | #[should_panic]
+   | ^^^^^^^^^^^^^^^
+
+warning: `#[ignore]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:342:1
+   |
+LL | #[ignore]
+   | ^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:377:1
+   |
+LL | #[reexport_test_harness_main = "2900"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:417:1
+   |
+LL | #[no_std]
+   | ^^^^^^^^^
+
+warning: attribute should be applied to a function definition
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:453:1
+   |
+LL |   #[cold]
+   |   ^^^^^^^
+...
+LL | / mod cold {
+LL | |
+LL | |
+LL | |     mod inner { #![cold] }
+...  |
+LL | |
+LL | | }
+   | |_- not a function definition
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a foreign function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:482:1
+   |
+LL |   #[link_name = "1900"]
+   |   ^^^^^^^^^^^^^^^^^^^^^
+...
+LL | / mod link_name {
+LL | |
+LL | |
+LL | |     #[link_name = "1900"]
+...  |
+LL | |
+LL | | }
+   | |_- not a foreign function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:521:1
+   |
+LL |   #[link_section = "1800"]
+   |   ^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | / mod link_section {
+LL | |
+LL | |
+LL | |     mod inner { #![link_section="1800"] }
+...  |
+LL | |
+LL | | }
+   | |_- not a function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to an `extern` block with non-Rust ABI
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:553:1
+   |
+LL |   #[link()]
+   |   ^^^^^^^^^
+...
+LL | / mod link {
+LL | |
+LL | |
+LL | |     mod inner { #![link()] }
+...  |
+LL | |
+LL | | }
+   | |_- not an `extern` block
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: `#[must_use]` has no effect when applied to a module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:604:1
+   |
+LL | #[must_use]
+   | ^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:617:1
+   |
+LL | #[windows_subsystem = "windows"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:638:1
+   |
+LL | #[crate_name = "0900"]
+   | ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:657:1
+   |
+LL | #[crate_type = "0800"]
+   | ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:676:1
+   |
+LL | #[feature(x0600)]
+   | ^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:696:1
+   |
+LL | #[no_main]
+   | ^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:715:1
+   |
+LL | #[no_builtins]
+   | ^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:734:1
+   |
+LL | #[recursion_limit="0200"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:753:1
+   |
+LL | #[type_length_limit="0100"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[should_panic]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:53:1
+   |
+LL | #![should_panic]
+   | ^^^^^^^^^^^^^^^^
+
+warning: `#[ignore]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:54:1
+   |
+LL | #![ignore]
+   | ^^^^^^^^^^
+
+warning: `#[proc_macro_derive]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:60:1
+   |
+LL | #![proc_macro_derive()]
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: attribute should be applied to a function definition
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:62:1
+   |
+LL | #![cold]
+   | ^^^^^^^^ cannot be applied to crates
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to an `extern` block with non-Rust ABI
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:64:1
+   |
+LL | #![link()]
+   | ^^^^^^^^^^ not an `extern` block
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a foreign function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:66:1
+   |
+LL | #![link_name = "1900"]
+   | ^^^^^^^^^^^^^^^^^^^^^^ not a foreign function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:69:1
+   |
+LL | #![link_section = "1800"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^ not a function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: `#[must_use]` has no effect when applied to a module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:72:1
+   |
+LL | #![must_use]
+   | ^^^^^^^^^^^^
+
+warning: `#[macro_use]` only has an effect on `extern crate` and modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:185:5
+   |
+LL |     #[macro_use] fn f() { }
+   |     ^^^^^^^^^^^^
+
+warning: `#[macro_use]` only has an effect on `extern crate` and modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:188:5
+   |
+LL |     #[macro_use] struct S;
+   |     ^^^^^^^^^^^^
+
+warning: `#[macro_use]` only has an effect on `extern crate` and modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:191:5
+   |
+LL |     #[macro_use] type T = S;
+   |     ^^^^^^^^^^^^
+
+warning: `#[macro_use]` only has an effect on `extern crate` and modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:194:5
+   |
+LL |     #[macro_use] impl S { }
+   |     ^^^^^^^^^^^^
+
+warning: `#[macro_export]` only has an effect on macro definitions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:201:17
+   |
+LL |     mod inner { #![macro_export] }
+   |                 ^^^^^^^^^^^^^^^^
+
+warning: `#[macro_export]` only has an effect on macro definitions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:204:5
+   |
+LL |     #[macro_export] fn f() { }
+   |     ^^^^^^^^^^^^^^^
+
+warning: `#[macro_export]` only has an effect on macro definitions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:207:5
+   |
+LL |     #[macro_export] struct S;
+   |     ^^^^^^^^^^^^^^^
+
+warning: `#[macro_export]` only has an effect on macro definitions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:210:5
+   |
+LL |     #[macro_export] type T = S;
+   |     ^^^^^^^^^^^^^^^
+
+warning: `#[macro_export]` only has an effect on macro definitions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:213:5
+   |
+LL |     #[macro_export] impl S { }
+   |     ^^^^^^^^^^^^^^^
+
+warning: `#[path]` only has an effect on modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:253:5
+   |
+LL |     #[path = "3800"] fn f() { }
+   |     ^^^^^^^^^^^^^^^^
+
+warning: `#[path]` only has an effect on modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:256:5
+   |
+LL |     #[path = "3800"]  struct S;
+   |     ^^^^^^^^^^^^^^^^
+
+warning: `#[path]` only has an effect on modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:259:5
+   |
+LL |     #[path = "3800"] type T = S;
+   |     ^^^^^^^^^^^^^^^^
+
+warning: `#[path]` only has an effect on modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:262:5
+   |
+LL |     #[path = "3800"] impl S { }
+   |     ^^^^^^^^^^^^^^^^
+
+warning: `#[automatically_derived]` only has an effect on implementation blocks
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:269:17
+   |
+LL |     mod inner { #![automatically_derived] }
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[automatically_derived]` only has an effect on implementation blocks
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:272:5
+   |
+LL |     #[automatically_derived] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[automatically_derived]` only has an effect on implementation blocks
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:275:5
+   |
+LL |     #[automatically_derived] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[automatically_derived]` only has an effect on implementation blocks
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:278:5
+   |
+LL |     #[automatically_derived] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:289:17
+   |
+LL |     mod inner { #![no_mangle] }
+   |     ------------^^^^^^^^^^^^^-- not a free function, impl method or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:296:5
+   |
+LL |     #[no_mangle] struct S;
+   |     ^^^^^^^^^^^^ --------- not a free function, impl method or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:301:5
+   |
+LL |     #[no_mangle] type T = S;
+   |     ^^^^^^^^^^^^ ----------- not a free function, impl method or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:306:5
+   |
+LL |     #[no_mangle] impl S { }
+   |     ^^^^^^^^^^^^ ---------- not a free function, impl method or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:312:9
+   |
+LL |         #[no_mangle] fn foo();
+   |         ^^^^^^^^^^^^ --------- not a free function, impl method or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a free function, impl method or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:317:9
+   |
+LL |         #[no_mangle] fn bar() {}
+   |         ^^^^^^^^^^^^ ----------- not a free function, impl method or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: `#[should_panic]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:327:17
+   |
+LL |     mod inner { #![should_panic] }
+   |                 ^^^^^^^^^^^^^^^^
+
+warning: `#[should_panic]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:332:5
+   |
+LL |     #[should_panic] struct S;
+   |     ^^^^^^^^^^^^^^^
+
+warning: `#[should_panic]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:335:5
+   |
+LL |     #[should_panic] type T = S;
+   |     ^^^^^^^^^^^^^^^
+
+warning: `#[should_panic]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:338:5
+   |
+LL |     #[should_panic] impl S { }
+   |     ^^^^^^^^^^^^^^^
+
+warning: `#[ignore]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:345:17
+   |
+LL |     mod inner { #![ignore] }
+   |                 ^^^^^^^^^^
+
+warning: `#[ignore]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:350:5
+   |
+LL |     #[ignore] struct S;
+   |     ^^^^^^^^^
+
+warning: `#[ignore]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:353:5
+   |
+LL |     #[ignore] type T = S;
+   |     ^^^^^^^^^
+
+warning: `#[ignore]` only has an effect on functions
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:356:5
+   |
+LL |     #[ignore] impl S { }
+   |     ^^^^^^^^^
+
+warning: `#[no_implicit_prelude]` only has an effect on modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:364:5
+   |
+LL |     #[no_implicit_prelude] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[no_implicit_prelude]` only has an effect on modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:367:5
+   |
+LL |     #[no_implicit_prelude] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[no_implicit_prelude]` only has an effect on modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:370:5
+   |
+LL |     #[no_implicit_prelude] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[no_implicit_prelude]` only has an effect on modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:373:5
+   |
+LL |     #[no_implicit_prelude] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be in the root module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:380:17
+   |
+LL |     mod inner { #![reexport_test_harness_main="2900"] }
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:383:5
+   |
+LL |     #[reexport_test_harness_main = "2900"] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:386:5
+   |
+LL |     #[reexport_test_harness_main = "2900"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:389:5
+   |
+LL |     #[reexport_test_harness_main = "2900"] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:392:5
+   |
+LL |     #[reexport_test_harness_main = "2900"] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: `#[macro_escape]` only has an effect on `extern crate` and modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:404:5
+   |
+LL |     #[macro_escape] fn f() { }
+   |     ^^^^^^^^^^^^^^^
+
+warning: `#[macro_escape]` only has an effect on `extern crate` and modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:407:5
+   |
+LL |     #[macro_escape] struct S;
+   |     ^^^^^^^^^^^^^^^
+
+warning: `#[macro_escape]` only has an effect on `extern crate` and modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:410:5
+   |
+LL |     #[macro_escape] type T = S;
+   |     ^^^^^^^^^^^^^^^
+
+warning: `#[macro_escape]` only has an effect on `extern crate` and modules
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:413:5
+   |
+LL |     #[macro_escape] impl S { }
+   |     ^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be in the root module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:420:17
+   |
+LL |     mod inner { #![no_std] }
+   |                 ^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:423:5
+   |
+LL |     #[no_std] fn f() { }
+   |     ^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:426:5
+   |
+LL |     #[no_std] struct S;
+   |     ^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:429:5
+   |
+LL |     #[no_std] type T = S;
+   |     ^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:432:5
+   |
+LL |     #[no_std] impl S { }
+   |     ^^^^^^^^^
+
+warning: attribute should be applied to a function definition
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:459:17
+   |
+LL |     mod inner { #![cold] }
+   |     ------------^^^^^^^^-- not a function definition
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a function definition
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:466:5
+   |
+LL |     #[cold] struct S;
+   |     ^^^^^^^ --------- not a function definition
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a function definition
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:471:5
+   |
+LL |     #[cold] type T = S;
+   |     ^^^^^^^ ----------- not a function definition
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a function definition
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:476:5
+   |
+LL |     #[cold] impl S { }
+   |     ^^^^^^^ ---------- not a function definition
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a foreign function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:488:5
+   |
+LL |     #[link_name = "1900"]
+   |     ^^^^^^^^^^^^^^^^^^^^^
+...
+LL |     extern "C" { }
+   |     -------------- not a foreign function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+help: try `#[link(name = "1900")]` instead
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:488:5
+   |
+LL |     #[link_name = "1900"]
+   |     ^^^^^^^^^^^^^^^^^^^^^
+
+warning: attribute should be applied to a foreign function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:495:17
+   |
+LL |     mod inner { #![link_name="1900"] }
+   |     ------------^^^^^^^^^^^^^^^^^^^^-- not a foreign function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a foreign function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:500:5
+   |
+LL |     #[link_name = "1900"] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^ ---------- not a foreign function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a foreign function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:505:5
+   |
+LL |     #[link_name = "1900"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^ --------- not a foreign function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a foreign function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:510:5
+   |
+LL |     #[link_name = "1900"] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^ ----------- not a foreign function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a foreign function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:515:5
+   |
+LL |     #[link_name = "1900"] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^ ---------- not a foreign function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:527:17
+   |
+LL |     mod inner { #![link_section="1800"] }
+   |     ------------^^^^^^^^^^^^^^^^^^^^^^^-- not a function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:534:5
+   |
+LL |     #[link_section = "1800"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^ --------- not a function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:539:5
+   |
+LL |     #[link_section = "1800"] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^ ----------- not a function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to a function or static
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:544:5
+   |
+LL |     #[link_section = "1800"] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^ ---------- not a function or static
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to an `extern` block with non-Rust ABI
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:559:17
+   |
+LL |     mod inner { #![link()] }
+   |     ------------^^^^^^^^^^-- not an `extern` block
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to an `extern` block with non-Rust ABI
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:564:5
+   |
+LL |     #[link()] fn f() { }
+   |     ^^^^^^^^^ ---------- not an `extern` block
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to an `extern` block with non-Rust ABI
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:569:5
+   |
+LL |     #[link()] struct S;
+   |     ^^^^^^^^^ --------- not an `extern` block
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to an `extern` block with non-Rust ABI
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:574:5
+   |
+LL |     #[link()] type T = S;
+   |     ^^^^^^^^^ ----------- not an `extern` block
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to an `extern` block with non-Rust ABI
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:579:5
+   |
+LL |     #[link()] impl S { }
+   |     ^^^^^^^^^ ---------- not an `extern` block
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: attribute should be applied to an `extern` block with non-Rust ABI
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:584:5
+   |
+LL |     #[link()] extern "Rust" {}
+   |     ^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+warning: `#[must_use]` has no effect when applied to a module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:606:17
+   |
+LL |     mod inner { #![must_use] }
+   |                 ^^^^^^^^^^^^
+
+warning: `#[must_use]` has no effect when applied to a type alias
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:612:5
+   |
+LL |     #[must_use] type T = S;
+   |     ^^^^^^^^^^^
+
+warning: `#[must_use]` has no effect when applied to an implementation block
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:614:5
+   |
+LL |     #[must_use] impl S { }
+   |     ^^^^^^^^^^^
+
+warning: crate-level attribute should be in the root module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:620:17
+   |
+LL |     mod inner { #![windows_subsystem="windows"] }
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:623:5
+   |
+LL |     #[windows_subsystem = "windows"] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:626:5
+   |
+LL |     #[windows_subsystem = "windows"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:629:5
+   |
+LL |     #[windows_subsystem = "windows"] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:632:5
+   |
+LL |     #[windows_subsystem = "windows"] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be in the root module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:641:17
+   |
+LL |     mod inner { #![crate_name="0900"] }
+   |                 ^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:644:5
+   |
+LL |     #[crate_name = "0900"] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:647:5
+   |
+LL |     #[crate_name = "0900"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:650:5
+   |
+LL |     #[crate_name = "0900"] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:653:5
+   |
+LL |     #[crate_name = "0900"] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be in the root module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:660:17
+   |
+LL |     mod inner { #![crate_type="0800"] }
+   |                 ^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:663:5
+   |
+LL |     #[crate_type = "0800"] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:666:5
+   |
+LL |     #[crate_type = "0800"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:669:5
+   |
+LL |     #[crate_type = "0800"] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:672:5
+   |
+LL |     #[crate_type = "0800"] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be in the root module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:679:17
+   |
+LL |     mod inner { #![feature(x0600)] }
+   |                 ^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:682:5
+   |
+LL |     #[feature(x0600)] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:685:5
+   |
+LL |     #[feature(x0600)] struct S;
+   |     ^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:688:5
+   |
+LL |     #[feature(x0600)] type T = S;
+   |     ^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:691:5
+   |
+LL |     #[feature(x0600)] impl S { }
+   |     ^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be in the root module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:699:17
+   |
+LL |     mod inner { #![no_main] }
+   |                 ^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:702:5
+   |
+LL |     #[no_main] fn f() { }
+   |     ^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:705:5
+   |
+LL |     #[no_main] struct S;
+   |     ^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:708:5
+   |
+LL |     #[no_main] type T = S;
+   |     ^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:711:5
+   |
+LL |     #[no_main] impl S { }
+   |     ^^^^^^^^^^
+
+warning: crate-level attribute should be in the root module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:718:17
+   |
+LL |     mod inner { #![no_builtins] }
+   |                 ^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:721:5
+   |
+LL |     #[no_builtins] fn f() { }
+   |     ^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:724:5
+   |
+LL |     #[no_builtins] struct S;
+   |     ^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:727:5
+   |
+LL |     #[no_builtins] type T = S;
+   |     ^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:730:5
+   |
+LL |     #[no_builtins] impl S { }
+   |     ^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be in the root module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:737:17
+   |
+LL |     mod inner { #![recursion_limit="0200"] }
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:740:5
+   |
+LL |     #[recursion_limit="0200"] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:743:5
+   |
+LL |     #[recursion_limit="0200"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:746:5
+   |
+LL |     #[recursion_limit="0200"] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:749:5
+   |
+LL |     #[recursion_limit="0200"] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be in the root module
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:756:17
+   |
+LL |     mod inner { #![type_length_limit="0100"] }
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:759:5
+   |
+LL |     #[type_length_limit="0100"] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:762:5
+   |
+LL |     #[type_length_limit="0100"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:765:5
+   |
+LL |     #[type_length_limit="0100"] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:768:5
+   |
+LL |     #[type_length_limit="0100"] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: the feature `rust1` has been stable since 1.0.0 and no longer requires an attribute to enable
+  --> $DIR/issue-43106-gating-of-builtin-attrs.rs:90:12
+   |
+LL | #![feature(rust1)]
+   |            ^^^^^
+   |
+   = note: `#[warn(stable_features)]` on by default
+
+warning: 173 warnings emitted
+
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-deprecated.rs b/tests/ui/feature-gates/issue-43106-gating-of-deprecated.rs
new file mode 100644
index 000000000..5e1d08dd9
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-deprecated.rs
@@ -0,0 +1,12 @@
+// This test just shows that a crate-level `#![deprecated]` does not
+// signal a warning or error. (This file sits on its own because a
+// crate-level `#![deprecated]` causes all that crate's item
+// definitions to be deprecated, which is a pain to work with.)
+//
+// (For non-crate-level cases, see issue-43106-gating-of-builtin-attrs.rs)
+
+// check-pass
+
+#![deprecated]
+
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-derive-2.rs b/tests/ui/feature-gates/issue-43106-gating-of-derive-2.rs
new file mode 100644
index 000000000..3276309f7
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-derive-2.rs
@@ -0,0 +1,20 @@
+// This test checks cases where the derive-macro does not exist.
+
+mod derive {
+    #[derive(x3300)]
+    //~^ ERROR cannot find derive macro `x3300` in this scope
+    //~| ERROR cannot find derive macro `x3300` in this scope
+    union U { f: i32 }
+
+    #[derive(x3300)]
+    //~^ ERROR cannot find derive macro `x3300` in this scope
+    //~| ERROR cannot find derive macro `x3300` in this scope
+    enum E { }
+
+    #[derive(x3300)]
+    //~^ ERROR cannot find derive macro `x3300` in this scope
+    //~| ERROR cannot find derive macro `x3300` in this scope
+    struct S;
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-derive-2.stderr b/tests/ui/feature-gates/issue-43106-gating-of-derive-2.stderr
new file mode 100644
index 000000000..ab1659173
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-derive-2.stderr
@@ -0,0 +1,38 @@
+error: cannot find derive macro `x3300` in this scope
+  --> $DIR/issue-43106-gating-of-derive-2.rs:14:14
+   |
+LL |     #[derive(x3300)]
+   |              ^^^^^
+
+error: cannot find derive macro `x3300` in this scope
+  --> $DIR/issue-43106-gating-of-derive-2.rs:14:14
+   |
+LL |     #[derive(x3300)]
+   |              ^^^^^
+
+error: cannot find derive macro `x3300` in this scope
+  --> $DIR/issue-43106-gating-of-derive-2.rs:9:14
+   |
+LL |     #[derive(x3300)]
+   |              ^^^^^
+
+error: cannot find derive macro `x3300` in this scope
+  --> $DIR/issue-43106-gating-of-derive-2.rs:9:14
+   |
+LL |     #[derive(x3300)]
+   |              ^^^^^
+
+error: cannot find derive macro `x3300` in this scope
+  --> $DIR/issue-43106-gating-of-derive-2.rs:4:14
+   |
+LL |     #[derive(x3300)]
+   |              ^^^^^
+
+error: cannot find derive macro `x3300` in this scope
+  --> $DIR/issue-43106-gating-of-derive-2.rs:4:14
+   |
+LL |     #[derive(x3300)]
+   |              ^^^^^
+
+error: aborting due to 6 previous errors
+
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-derive.rs b/tests/ui/feature-gates/issue-43106-gating-of-derive.rs
new file mode 100644
index 000000000..86a352251
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-derive.rs
@@ -0,0 +1,33 @@
+// `#![derive]` raises errors when it occurs at contexts other than ADT
+// definitions.
+
+#[derive(Debug)]
+//~^ ERROR `derive` may only be applied to `struct`s, `enum`s and `union`s
+mod derive {
+    mod inner { #![derive(Debug)] }
+    //~^ ERROR `derive` may only be applied to `struct`s, `enum`s and `union`s
+    //~| ERROR inner macro attributes are unstable
+
+    #[derive(Debug)]
+    //~^ ERROR `derive` may only be applied to `struct`s, `enum`s and `union`s
+    fn derive() { }
+
+    #[derive(Copy, Clone)] // (can't derive Debug for unions)
+    union U { f: i32 }
+
+    #[derive(Debug)]
+    struct S;
+
+    #[derive(Debug)]
+    enum E { }
+
+    #[derive(Debug)]
+    //~^ ERROR `derive` may only be applied to `struct`s, `enum`s and `union`s
+    type T = S;
+
+    #[derive(Debug)]
+    //~^ ERROR `derive` may only be applied to `struct`s, `enum`s and `union`s
+    impl S { }
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-derive.stderr b/tests/ui/feature-gates/issue-43106-gating-of-derive.stderr
new file mode 100644
index 000000000..bb8651ffb
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-derive.stderr
@@ -0,0 +1,64 @@
+error[E0774]: `derive` may only be applied to `struct`s, `enum`s and `union`s
+  --> $DIR/issue-43106-gating-of-derive.rs:4:1
+   |
+LL |   #[derive(Debug)]
+   |   ^^^^^^^^^^^^^^^^ not applicable here
+LL |
+LL | / mod derive {
+LL | |     mod inner { #![derive(Debug)] }
+LL | |
+LL | |
+...  |
+LL | |     impl S { }
+LL | | }
+   | |_- not a `struct`, `enum` or `union`
+
+error[E0658]: inner macro attributes are unstable
+  --> $DIR/issue-43106-gating-of-derive.rs:7:20
+   |
+LL |     mod inner { #![derive(Debug)] }
+   |                    ^^^^^^
+   |
+   = note: see issue #54726 <https://github.com/rust-lang/rust/issues/54726> for more information
+   = help: add `#![feature(custom_inner_attributes)]` to the crate attributes to enable
+
+error[E0774]: `derive` may only be applied to `struct`s, `enum`s and `union`s
+  --> $DIR/issue-43106-gating-of-derive.rs:7:17
+   |
+LL |     mod inner { #![derive(Debug)] }
+   |     ------------^^^^^^^^^^^^^^^^^--
+   |     |           |
+   |     |           not applicable here
+   |     not a `struct`, `enum` or `union`
+
+error[E0774]: `derive` may only be applied to `struct`s, `enum`s and `union`s
+  --> $DIR/issue-43106-gating-of-derive.rs:11:5
+   |
+LL |     #[derive(Debug)]
+   |     ^^^^^^^^^^^^^^^^ not applicable here
+LL |
+LL |     fn derive() { }
+   |     --------------- not a `struct`, `enum` or `union`
+
+error[E0774]: `derive` may only be applied to `struct`s, `enum`s and `union`s
+  --> $DIR/issue-43106-gating-of-derive.rs:24:5
+   |
+LL |     #[derive(Debug)]
+   |     ^^^^^^^^^^^^^^^^ not applicable here
+LL |
+LL |     type T = S;
+   |     ----------- not a `struct`, `enum` or `union`
+
+error[E0774]: `derive` may only be applied to `struct`s, `enum`s and `union`s
+  --> $DIR/issue-43106-gating-of-derive.rs:28:5
+   |
+LL |     #[derive(Debug)]
+   |     ^^^^^^^^^^^^^^^^ not applicable here
+LL |
+LL |     impl S { }
+   |     ---------- not a `struct`, `enum` or `union`
+
+error: aborting due to 6 previous errors
+
+Some errors have detailed explanations: E0658, E0774.
+For more information about an error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-macro_escape.rs b/tests/ui/feature-gates/issue-43106-gating-of-macro_escape.rs
new file mode 100644
index 000000000..de00bc4cb
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-macro_escape.rs
@@ -0,0 +1,11 @@
+// Testing that crate-level `#![macro_escape]` is not gated beyond a
+// depecation warning.  This file sits on its own, because crate-level
+// `#![macro_escape]` is incompatible with crate-level `#![macro_use]`
+// already present in issue-43106-gating-of-builtin-attrs.
+
+// check-pass
+
+#![macro_escape]
+//~^ WARN `#[macro_escape]` is a deprecated synonym for `#[macro_use]`
+
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-macro_escape.stderr b/tests/ui/feature-gates/issue-43106-gating-of-macro_escape.stderr
new file mode 100644
index 000000000..0eaec5202
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-macro_escape.stderr
@@ -0,0 +1,10 @@
+warning: `#[macro_escape]` is a deprecated synonym for `#[macro_use]`
+  --> $DIR/issue-43106-gating-of-macro_escape.rs:8:1
+   |
+LL | #![macro_escape]
+   | ^^^^^^^^^^^^^^^^
+   |
+   = help: try an outer attribute: `#[macro_use]`
+
+warning: 1 warning emitted
+
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-macro_use.rs b/tests/ui/feature-gates/issue-43106-gating-of-macro_use.rs
new file mode 100644
index 000000000..6a7ef7939
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-macro_use.rs
@@ -0,0 +1,25 @@
+// This is just a check-list of the cases where feeding arguments to
+// `#[macro_use]` is rejected. (The cases where no error is emitted
+// corresponds to cases where the attribute is currently unused, so we
+// get that warning; see issue-43106-gating-of-builtin-attrs.rs
+
+#![macro_use(my_macro)]
+//~^ ERROR arguments to `macro_use` are not allowed here
+
+#[macro_use(my_macro)]
+//~^ ERROR arguments to `macro_use` are not allowed here
+mod macro_escape {
+    mod inner { #![macro_use(my_macro)] }
+    //~^ ERROR arguments to `macro_use` are not allowed here
+
+    #[macro_use = "2700"] struct S;
+    //~^ ERROR malformed `macro_use` attribute
+
+    #[macro_use] fn f() { }
+
+    #[macro_use] type T = S;
+
+    #[macro_use] impl S { }
+}
+
+fn main() { }
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-macro_use.stderr b/tests/ui/feature-gates/issue-43106-gating-of-macro_use.stderr
new file mode 100644
index 000000000..9a12851f2
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-macro_use.stderr
@@ -0,0 +1,33 @@
+error: arguments to `macro_use` are not allowed here
+  --> $DIR/issue-43106-gating-of-macro_use.rs:12:17
+   |
+LL |     mod inner { #![macro_use(my_macro)] }
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: arguments to `macro_use` are not allowed here
+  --> $DIR/issue-43106-gating-of-macro_use.rs:9:1
+   |
+LL | #[macro_use(my_macro)]
+   | ^^^^^^^^^^^^^^^^^^^^^^
+
+error: arguments to `macro_use` are not allowed here
+  --> $DIR/issue-43106-gating-of-macro_use.rs:6:1
+   |
+LL | #![macro_use(my_macro)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: malformed `macro_use` attribute input
+  --> $DIR/issue-43106-gating-of-macro_use.rs:15:5
+   |
+LL |     #[macro_use = "2700"] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^
+   |
+help: the following are the possible correct uses
+   |
+LL |     #[macro_use(name1, name2, ...)] struct S;
+   |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+LL |     #[macro_use] struct S;
+   |     ~~~~~~~~~~~~
+
+error: aborting due to 4 previous errors
+
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-proc_macro_derive.rs b/tests/ui/feature-gates/issue-43106-gating-of-proc_macro_derive.rs
new file mode 100644
index 000000000..a94ffd602
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-proc_macro_derive.rs
@@ -0,0 +1,34 @@
+// At time of authorship, #[proc_macro_derive = "2500"] will emit an
+// error when it occurs on a mod (apart from crate-level), but will
+// not descend further into the mod for other occurrences of the same
+// error.
+//
+// This file sits on its own because the "weird" occurrences here
+// signal errors, making it incompatible with the "warnings only"
+// nature of issue-43106-gating-of-builtin-attrs.rs
+
+#[proc_macro_derive()]
+//~^ ERROR the `#[proc_macro_derive]` attribute may only be used on bare functions
+mod proc_macro_derive1 {
+    mod inner { #![proc_macro_derive()] }
+    // (no error issued here if there was one on outer module)
+}
+
+mod proc_macro_derive2 {
+    mod inner { #![proc_macro_derive()] }
+    //~^ ERROR the `#[proc_macro_derive]` attribute may only be used on bare functions
+
+    #[proc_macro_derive()] fn f() { }
+    //~^ ERROR the `#[proc_macro_derive]` attribute is only usable with crates of the `proc-macro`
+
+    #[proc_macro_derive()] struct S;
+    //~^ ERROR the `#[proc_macro_derive]` attribute may only be used on bare functions
+
+    #[proc_macro_derive()] type T = S;
+    //~^ ERROR the `#[proc_macro_derive]` attribute may only be used on bare functions
+
+    #[proc_macro_derive()] impl S { }
+    //~^ ERROR the `#[proc_macro_derive]` attribute may only be used on bare functions
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-proc_macro_derive.stderr b/tests/ui/feature-gates/issue-43106-gating-of-proc_macro_derive.stderr
new file mode 100644
index 000000000..e202b472d
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-proc_macro_derive.stderr
@@ -0,0 +1,38 @@
+error: the `#[proc_macro_derive]` attribute may only be used on bare functions
+  --> $DIR/issue-43106-gating-of-proc_macro_derive.rs:10:1
+   |
+LL | #[proc_macro_derive()]
+   | ^^^^^^^^^^^^^^^^^^^^^^
+
+error: the `#[proc_macro_derive]` attribute may only be used on bare functions
+  --> $DIR/issue-43106-gating-of-proc_macro_derive.rs:18:17
+   |
+LL |     mod inner { #![proc_macro_derive()] }
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: the `#[proc_macro_derive]` attribute is only usable with crates of the `proc-macro` crate type
+  --> $DIR/issue-43106-gating-of-proc_macro_derive.rs:21:5
+   |
+LL |     #[proc_macro_derive()] fn f() { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+error: the `#[proc_macro_derive]` attribute may only be used on bare functions
+  --> $DIR/issue-43106-gating-of-proc_macro_derive.rs:24:5
+   |
+LL |     #[proc_macro_derive()] struct S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+error: the `#[proc_macro_derive]` attribute may only be used on bare functions
+  --> $DIR/issue-43106-gating-of-proc_macro_derive.rs:27:5
+   |
+LL |     #[proc_macro_derive()] type T = S;
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+error: the `#[proc_macro_derive]` attribute may only be used on bare functions
+  --> $DIR/issue-43106-gating-of-proc_macro_derive.rs:30:5
+   |
+LL |     #[proc_macro_derive()] impl S { }
+   |     ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 6 previous errors
+
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-stable.rs b/tests/ui/feature-gates/issue-43106-gating-of-stable.rs
new file mode 100644
index 000000000..621ec01bb
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-stable.rs
@@ -0,0 +1,35 @@
+// Testing gating of `#[stable]` in "weird" places.
+//
+// This file sits on its own because these signal errors, making
+// this test incompatible with the "warnings only" nature of
+// issue-43106-gating-of-builtin-attrs.rs
+
+#![stable()]
+//~^ ERROR stability attributes may not be used outside of the standard library
+
+#[stable()]
+//~^ ERROR stability attributes may not be used outside of the standard library
+mod stable {
+    mod inner {
+        #![stable()]
+        //~^ ERROR stability attributes may not be used outside of the standard library
+    }
+
+    #[stable()]
+    //~^ ERROR stability attributes may not be used outside of the standard library
+    fn f() {}
+
+    #[stable()]
+    //~^ ERROR stability attributes may not be used outside of the standard library
+    struct S;
+
+    #[stable()]
+    //~^ ERROR stability attributes may not be used outside of the standard library
+    type T = S;
+
+    #[stable()]
+    //~^ ERROR stability attributes may not be used outside of the standard library
+    impl S {}
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-stable.stderr b/tests/ui/feature-gates/issue-43106-gating-of-stable.stderr
new file mode 100644
index 000000000..677fef3a9
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-stable.stderr
@@ -0,0 +1,45 @@
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-stable.rs:14:9
+   |
+LL |         #![stable()]
+   |         ^^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-stable.rs:18:5
+   |
+LL |     #[stable()]
+   |     ^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-stable.rs:22:5
+   |
+LL |     #[stable()]
+   |     ^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-stable.rs:26:5
+   |
+LL |     #[stable()]
+   |     ^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-stable.rs:30:5
+   |
+LL |     #[stable()]
+   |     ^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-stable.rs:10:1
+   |
+LL | #[stable()]
+   | ^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-stable.rs:7:1
+   |
+LL | #![stable()]
+   | ^^^^^^^^^^^^
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0734`.
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-test.rs b/tests/ui/feature-gates/issue-43106-gating-of-test.rs
new file mode 100644
index 000000000..39835c926
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-test.rs
@@ -0,0 +1,7 @@
+// The non-crate level cases are in issue-43106-gating-of-builtin-attrs.rs.
+
+#![allow(soft_unstable)]
+#![test                    = "4200"]
+//~^ ERROR cannot determine resolution for the attribute macro `test`
+//~^^ ERROR `test` attribute cannot be used at crate level
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-test.stderr b/tests/ui/feature-gates/issue-43106-gating-of-test.stderr
new file mode 100644
index 000000000..300a9966d
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-test.stderr
@@ -0,0 +1,21 @@
+error: cannot determine resolution for the attribute macro `test`
+  --> $DIR/issue-43106-gating-of-test.rs:4:4
+   |
+LL | #![test                    = "4200"]
+   |    ^^^^
+   |
+   = note: import resolution is stuck, try simplifying macro imports
+
+error: `test` attribute cannot be used at crate level
+  --> $DIR/issue-43106-gating-of-test.rs:4:1
+   |
+LL | #![test                    = "4200"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[test                    = "4200"]
+   |
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-unstable.rs b/tests/ui/feature-gates/issue-43106-gating-of-unstable.rs
new file mode 100644
index 000000000..d507bcd8f
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-unstable.rs
@@ -0,0 +1,35 @@
+// Testing gating of `#[unstable]` in "weird" places.
+//
+// This file sits on its own because these signal errors, making
+// this test incompatible with the "warnings only" nature of
+// issue-43106-gating-of-builtin-attrs.rs
+
+#![unstable()]
+//~^ ERROR stability attributes may not be used outside of the standard library
+
+#[unstable()]
+//~^ ERROR stability attributes may not be used outside of the standard library
+mod unstable {
+    mod inner {
+        #![unstable()]
+        //~^ ERROR stability attributes may not be used outside of the standard library
+    }
+
+    #[unstable()]
+    //~^ ERROR stability attributes may not be used outside of the standard library
+    fn f() {}
+
+    #[unstable()]
+    //~^ ERROR stability attributes may not be used outside of the standard library
+    struct S;
+
+    #[unstable()]
+    //~^ ERROR stability attributes may not be used outside of the standard library
+    type T = S;
+
+    #[unstable()]
+    //~^ ERROR stability attributes may not be used outside of the standard library
+    impl S {}
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-43106-gating-of-unstable.stderr b/tests/ui/feature-gates/issue-43106-gating-of-unstable.stderr
new file mode 100644
index 000000000..a2f361878
--- /dev/null
+++ b/tests/ui/feature-gates/issue-43106-gating-of-unstable.stderr
@@ -0,0 +1,45 @@
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-unstable.rs:14:9
+   |
+LL |         #![unstable()]
+   |         ^^^^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-unstable.rs:18:5
+   |
+LL |     #[unstable()]
+   |     ^^^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-unstable.rs:22:5
+   |
+LL |     #[unstable()]
+   |     ^^^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-unstable.rs:26:5
+   |
+LL |     #[unstable()]
+   |     ^^^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-unstable.rs:30:5
+   |
+LL |     #[unstable()]
+   |     ^^^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-unstable.rs:10:1
+   |
+LL | #[unstable()]
+   | ^^^^^^^^^^^^^
+
+error[E0734]: stability attributes may not be used outside of the standard library
+  --> $DIR/issue-43106-gating-of-unstable.rs:7:1
+   |
+LL | #![unstable()]
+   | ^^^^^^^^^^^^^^
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0734`.
diff --git a/tests/ui/feature-gates/issue-49983-see-issue-0.rs b/tests/ui/feature-gates/issue-49983-see-issue-0.rs
new file mode 100644
index 000000000..eeb80d014
--- /dev/null
+++ b/tests/ui/feature-gates/issue-49983-see-issue-0.rs
@@ -0,0 +1,6 @@
+extern crate core;
+
+// error should not say "(see issue #0)"
+#[allow(unused_imports)] use core::ptr::Unique; //~ ERROR use of unstable library feature
+
+fn main() {}
diff --git a/tests/ui/feature-gates/issue-49983-see-issue-0.stderr b/tests/ui/feature-gates/issue-49983-see-issue-0.stderr
new file mode 100644
index 000000000..314238a34
--- /dev/null
+++ b/tests/ui/feature-gates/issue-49983-see-issue-0.stderr
@@ -0,0 +1,11 @@
+error[E0658]: use of unstable library feature 'ptr_internals': use `NonNull` instead and consider `PhantomData<T>` (if you also use `#[may_dangle]`), `Send`, and/or `Sync`
+  --> $DIR/issue-49983-see-issue-0.rs:4:30
+   |
+LL | #[allow(unused_imports)] use core::ptr::Unique;
+   |                              ^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(ptr_internals)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/rustc-private.rs b/tests/ui/feature-gates/rustc-private.rs
new file mode 100644
index 000000000..7b8944bb0
--- /dev/null
+++ b/tests/ui/feature-gates/rustc-private.rs
@@ -0,0 +1,5 @@
+// gate-test-rustc_private
+
+extern crate libc; //~ ERROR  use of unstable library feature 'rustc_private'
+
+fn main() {}
diff --git a/tests/ui/feature-gates/rustc-private.stderr b/tests/ui/feature-gates/rustc-private.stderr
new file mode 100644
index 000000000..1a8536d37
--- /dev/null
+++ b/tests/ui/feature-gates/rustc-private.stderr
@@ -0,0 +1,12 @@
+error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead?
+  --> $DIR/rustc-private.rs:3:1
+   |
+LL | extern crate libc;
+   | ^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #27812 <https://github.com/rust-lang/rust/issues/27812> for more information
+   = help: add `#![feature(rustc_private)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/soft-syntax-gates-with-errors.rs b/tests/ui/feature-gates/soft-syntax-gates-with-errors.rs
new file mode 100644
index 000000000..49f1cba71
--- /dev/null
+++ b/tests/ui/feature-gates/soft-syntax-gates-with-errors.rs
@@ -0,0 +1,30 @@
+// check-fail
+// This file is used to test the behavior of the early-pass syntax warnings.
+// If macro syntax is stabilized, replace with a different unstable syntax.
+
+macro a() {}
+//~^ ERROR: `macro` is experimental
+
+#[cfg(FALSE)]
+macro b() {}
+
+macro_rules! identity {
+    ($($x:tt)*) => ($($x)*);
+}
+
+identity! {
+    macro c() {}
+    //~^ ERROR: `macro` is experimental
+}
+
+#[cfg(FALSE)]
+identity! {
+    macro d() {} // No error
+}
+
+identity! {
+    #[cfg(FALSE)]
+    macro e() {}
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/soft-syntax-gates-with-errors.stderr b/tests/ui/feature-gates/soft-syntax-gates-with-errors.stderr
new file mode 100644
index 000000000..49550d811
--- /dev/null
+++ b/tests/ui/feature-gates/soft-syntax-gates-with-errors.stderr
@@ -0,0 +1,21 @@
+error[E0658]: `macro` is experimental
+  --> $DIR/soft-syntax-gates-with-errors.rs:5:1
+   |
+LL | macro a() {}
+   | ^^^^^^^^^^^^
+   |
+   = note: see issue #39412 <https://github.com/rust-lang/rust/issues/39412> for more information
+   = help: add `#![feature(decl_macro)]` to the crate attributes to enable
+
+error[E0658]: `macro` is experimental
+  --> $DIR/soft-syntax-gates-with-errors.rs:16:5
+   |
+LL |     macro c() {}
+   |     ^^^^^^^^^^^^
+   |
+   = note: see issue #39412 <https://github.com/rust-lang/rust/issues/39412> for more information
+   = help: add `#![feature(decl_macro)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/soft-syntax-gates-without-errors.rs b/tests/ui/feature-gates/soft-syntax-gates-without-errors.rs
new file mode 100644
index 000000000..ca4ad2320
--- /dev/null
+++ b/tests/ui/feature-gates/soft-syntax-gates-without-errors.rs
@@ -0,0 +1,26 @@
+// check-pass
+// This file is used to test the behavior of the early-pass syntax warnings.
+// If macro syntax is stabilized, replace with a different unstable syntax.
+
+#[cfg(FALSE)]
+macro b() {}
+//~^ WARN: `macro` is experimental
+//~| WARN: unstable syntax
+
+macro_rules! identity {
+    ($($x:tt)*) => ($($x)*);
+}
+
+#[cfg(FALSE)]
+identity! {
+    macro d() {} // No error
+}
+
+identity! {
+    #[cfg(FALSE)]
+    macro e() {}
+    //~^ WARN: `macro` is experimental
+    //~| WARN: unstable syntax
+}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/soft-syntax-gates-without-errors.stderr b/tests/ui/feature-gates/soft-syntax-gates-without-errors.stderr
new file mode 100644
index 000000000..3d9c22e54
--- /dev/null
+++ b/tests/ui/feature-gates/soft-syntax-gates-without-errors.stderr
@@ -0,0 +1,24 @@
+warning: `macro` is experimental
+  --> $DIR/soft-syntax-gates-without-errors.rs:6:1
+   |
+LL | macro b() {}
+   | ^^^^^^^^^^^^
+   |
+   = note: see issue #39412 <https://github.com/rust-lang/rust/issues/39412> for more information
+   = help: add `#![feature(decl_macro)]` to the crate attributes to enable
+   = warning: unstable syntax can change at any point in the future, causing a hard error!
+   = note: for more information, see issue #65860 <https://github.com/rust-lang/rust/issues/65860>
+
+warning: `macro` is experimental
+  --> $DIR/soft-syntax-gates-without-errors.rs:21:5
+   |
+LL |     macro e() {}
+   |     ^^^^^^^^^^^^
+   |
+   = note: see issue #39412 <https://github.com/rust-lang/rust/issues/39412> for more information
+   = help: add `#![feature(decl_macro)]` to the crate attributes to enable
+   = warning: unstable syntax can change at any point in the future, causing a hard error!
+   = note: for more information, see issue #65860 <https://github.com/rust-lang/rust/issues/65860>
+
+warning: 2 warnings emitted
+
diff --git a/tests/ui/feature-gates/stability-attribute-consistency.rs b/tests/ui/feature-gates/stability-attribute-consistency.rs
new file mode 100644
index 000000000..6ee7003c3
--- /dev/null
+++ b/tests/ui/feature-gates/stability-attribute-consistency.rs
@@ -0,0 +1,16 @@
+#![stable(feature = "stable_test_feature", since = "1.0.0")]
+
+#![feature(staged_api)]
+
+#[stable(feature = "foo", since = "1.0.0")]
+fn foo_stable_1_0_0() {}
+
+#[stable(feature = "foo", since = "1.29.0")]
+//~^ ERROR feature `foo` is declared stable since 1.29.0
+fn foo_stable_1_29_0() {}
+
+#[unstable(feature = "foo", issue = "none")]
+//~^ ERROR feature `foo` is declared unstable
+fn foo_unstable() {}
+
+fn main() {}
diff --git a/tests/ui/feature-gates/stability-attribute-consistency.stderr b/tests/ui/feature-gates/stability-attribute-consistency.stderr
new file mode 100644
index 000000000..1b93d3c96
--- /dev/null
+++ b/tests/ui/feature-gates/stability-attribute-consistency.stderr
@@ -0,0 +1,15 @@
+error[E0711]: feature `foo` is declared stable since 1.29.0, but was previously declared stable since 1.0.0
+  --> $DIR/stability-attribute-consistency.rs:8:1
+   |
+LL | #[stable(feature = "foo", since = "1.29.0")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0711]: feature `foo` is declared unstable, but was previously declared stable
+  --> $DIR/stability-attribute-consistency.rs:12:1
+   |
+LL | #[unstable(feature = "foo", issue = "none")]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0711`.
diff --git a/tests/ui/feature-gates/stable-features.rs b/tests/ui/feature-gates/stable-features.rs
new file mode 100644
index 000000000..ed7f0899d
--- /dev/null
+++ b/tests/ui/feature-gates/stable-features.rs
@@ -0,0 +1,14 @@
+// Testing that the stable_features lint catches use of stable
+// language and lib features.
+
+#![deny(stable_features)]
+
+#![feature(test_accepted_feature)]
+//~^ ERROR the feature `test_accepted_feature` has been stable since 1.0.0
+
+#![feature(rust1)]
+//~^ ERROR the feature `rust1` has been stable since 1.0.0
+
+fn main() {
+    let _foo: Vec<()> = Vec::new();
+}
diff --git a/tests/ui/feature-gates/stable-features.stderr b/tests/ui/feature-gates/stable-features.stderr
new file mode 100644
index 000000000..831b40b86
--- /dev/null
+++ b/tests/ui/feature-gates/stable-features.stderr
@@ -0,0 +1,20 @@
+error: the feature `test_accepted_feature` has been stable since 1.0.0 and no longer requires an attribute to enable
+  --> $DIR/stable-features.rs:6:12
+   |
+LL | #![feature(test_accepted_feature)]
+   |            ^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/stable-features.rs:4:9
+   |
+LL | #![deny(stable_features)]
+   |         ^^^^^^^^^^^^^^^
+
+error: the feature `rust1` has been stable since 1.0.0 and no longer requires an attribute to enable
+  --> $DIR/stable-features.rs:9:12
+   |
+LL | #![feature(rust1)]
+   |            ^^^^^
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/feature-gates/trace_macros-gate.rs b/tests/ui/feature-gates/trace_macros-gate.rs
new file mode 100644
index 000000000..c9af04741
--- /dev/null
+++ b/tests/ui/feature-gates/trace_macros-gate.rs
@@ -0,0 +1,14 @@
+// Test that the trace_macros feature gate is on.
+
+fn main() {
+    trace_macros!(); //~ ERROR `trace_macros` is not stable
+                     //~| ERROR trace_macros! accepts only `true` or `false`
+    trace_macros!(true); //~ ERROR `trace_macros` is not stable
+    trace_macros!(false); //~ ERROR `trace_macros` is not stable
+
+    macro_rules! expando {
+        ($x: ident) => { trace_macros!($x) } //~ ERROR `trace_macros` is not stable
+    }
+
+    expando!(true);
+}
diff --git a/tests/ui/feature-gates/trace_macros-gate.stderr b/tests/ui/feature-gates/trace_macros-gate.stderr
new file mode 100644
index 000000000..1ca10aeec
--- /dev/null
+++ b/tests/ui/feature-gates/trace_macros-gate.stderr
@@ -0,0 +1,49 @@
+error[E0658]: use of unstable library feature 'trace_macros': `trace_macros` is not stable enough for use and is subject to change
+  --> $DIR/trace_macros-gate.rs:4:5
+   |
+LL |     trace_macros!();
+   |     ^^^^^^^^^^^^
+   |
+   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
+   = help: add `#![feature(trace_macros)]` to the crate attributes to enable
+
+error: trace_macros! accepts only `true` or `false`
+  --> $DIR/trace_macros-gate.rs:4:5
+   |
+LL |     trace_macros!();
+   |     ^^^^^^^^^^^^^^^
+
+error[E0658]: use of unstable library feature 'trace_macros': `trace_macros` is not stable enough for use and is subject to change
+  --> $DIR/trace_macros-gate.rs:6:5
+   |
+LL |     trace_macros!(true);
+   |     ^^^^^^^^^^^^
+   |
+   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
+   = help: add `#![feature(trace_macros)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'trace_macros': `trace_macros` is not stable enough for use and is subject to change
+  --> $DIR/trace_macros-gate.rs:7:5
+   |
+LL |     trace_macros!(false);
+   |     ^^^^^^^^^^^^
+   |
+   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
+   = help: add `#![feature(trace_macros)]` to the crate attributes to enable
+
+error[E0658]: use of unstable library feature 'trace_macros': `trace_macros` is not stable enough for use and is subject to change
+  --> $DIR/trace_macros-gate.rs:10:26
+   |
+LL |         ($x: ident) => { trace_macros!($x) }
+   |                          ^^^^^^^^^^^^
+...
+LL |     expando!(true);
+   |     -------------- in this macro invocation
+   |
+   = note: see issue #29598 <https://github.com/rust-lang/rust/issues/29598> for more information
+   = help: add `#![feature(trace_macros)]` to the crate attributes to enable
+   = note: this error originates in the macro `expando` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/feature-gates/unknown-feature.rs b/tests/ui/feature-gates/unknown-feature.rs
new file mode 100644
index 000000000..20fd932d4
--- /dev/null
+++ b/tests/ui/feature-gates/unknown-feature.rs
@@ -0,0 +1,3 @@
+#![feature(unknown_rust_feature)] //~ ERROR unknown feature
+
+fn main() {}
diff --git a/tests/ui/feature-gates/unknown-feature.stderr b/tests/ui/feature-gates/unknown-feature.stderr
new file mode 100644
index 000000000..e5c05872d
--- /dev/null
+++ b/tests/ui/feature-gates/unknown-feature.stderr
@@ -0,0 +1,9 @@
+error[E0635]: unknown feature `unknown_rust_feature`
+  --> $DIR/unknown-feature.rs:1:12
+   |
+LL | #![feature(unknown_rust_feature)]
+   |            ^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0635`.
diff --git a/tests/ui/feature-gates/unstable-attribute-allow-issue-0.rs b/tests/ui/feature-gates/unstable-attribute-allow-issue-0.rs
new file mode 100644
index 000000000..bffe43262
--- /dev/null
+++ b/tests/ui/feature-gates/unstable-attribute-allow-issue-0.rs
@@ -0,0 +1,13 @@
+// Check that an issue value can be explicitly set to "0" instead of "none"
+#![crate_type = "lib"]
+#![feature(staged_api)]
+#![stable(feature = "stable_test_feature", since = "1.0.0")]
+
+#[unstable(feature = "unstable_test_feature", issue = "0")]
+fn unstable_issue_0() {} //~^ ERROR `issue` must be a non-zero numeric string or "none"
+
+#[unstable(feature = "unstable_test_feature", issue = "none")]
+fn unstable_issue_none() {}
+
+#[unstable(feature = "unstable_test_feature", issue = "something")]
+fn unstable_issue_not_allowed() {} //~^ ERROR `issue` must be a non-zero numeric string or "none"
diff --git a/tests/ui/feature-gates/unstable-attribute-allow-issue-0.stderr b/tests/ui/feature-gates/unstable-attribute-allow-issue-0.stderr
new file mode 100644
index 000000000..4ed42101a
--- /dev/null
+++ b/tests/ui/feature-gates/unstable-attribute-allow-issue-0.stderr
@@ -0,0 +1,19 @@
+error[E0545]: `issue` must be a non-zero numeric string or "none"
+  --> $DIR/unstable-attribute-allow-issue-0.rs:6:47
+   |
+LL | #[unstable(feature = "unstable_test_feature", issue = "0")]
+   |                                               ^^^^^^^^---
+   |                                                       |
+   |                                                       `issue` must not be "0", use "none" instead
+
+error[E0545]: `issue` must be a non-zero numeric string or "none"
+  --> $DIR/unstable-attribute-allow-issue-0.rs:12:47
+   |
+LL | #[unstable(feature = "unstable_test_feature", issue = "something")]
+   |                                               ^^^^^^^^-----------
+   |                                                       |
+   |                                                       invalid digit found in string
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0545`.