Merging upstream version 1.68.2+dfsg1.

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

35 files changed, 1281 insertions, 0 deletions

diff --git a/tests/ui/repr/align-with-extern-c-fn.rs b/tests/ui/repr/align-with-extern-c-fn.rs
new file mode 100644
index 000000000..9e490e27a
--- /dev/null
+++ b/tests/ui/repr/align-with-extern-c-fn.rs
@@ -0,0 +1,18 @@
+// run-pass
+
+#![allow(stable_features)]
+#![allow(unused_variables)]
+
+// #45662
+
+#![feature(repr_align)]
+
+#[repr(align(16))]
+pub struct A(#[allow(unused_tuple_struct_fields)] i64);
+
+#[allow(improper_ctypes_definitions)]
+pub extern "C" fn foo(x: A) {}
+
+fn main() {
+    foo(A(0));
+}
diff --git a/tests/ui/repr/aligned_enum_cast.rs b/tests/ui/repr/aligned_enum_cast.rs
new file mode 100644
index 000000000..1ddf12717
--- /dev/null
+++ b/tests/ui/repr/aligned_enum_cast.rs
@@ -0,0 +1,25 @@
+// run-pass
+// allows aligned custom discriminant enums to cast into other types
+// See the issue #92464 for more info
+#[allow(dead_code)]
+#[repr(align(8))]
+enum Aligned {
+    Zero = 0,
+    One = 1,
+}
+
+fn main() {
+    let aligned = Aligned::Zero;
+    let fo = aligned as u8;
+    println!("foo {}", fo);
+    assert_eq!(fo, 0);
+    println!("{}", tou8(Aligned::Zero));
+    assert_eq!(tou8(Aligned::Zero), 0);
+}
+
+#[inline(never)]
+fn tou8(al: Aligned) -> u8 {
+    // Cast behind a function call so ConstProp does not see it
+    // (so that we can test codegen).
+    al as u8
+}
diff --git a/tests/ui/repr/attr-usage-repr.rs b/tests/ui/repr/attr-usage-repr.rs
new file mode 100644
index 000000000..8965decc3
--- /dev/null
+++ b/tests/ui/repr/attr-usage-repr.rs
@@ -0,0 +1,33 @@
+#![feature(repr_simd)]
+
+#[repr(C)] //~ ERROR: attribute should be applied to a struct, enum, or union
+fn f() {}
+
+#[repr(C)]
+struct SExtern(f64, f64);
+
+#[repr(packed)]
+struct SPacked(f64, f64);
+
+#[repr(simd)]
+struct SSimd(f64, f64);
+
+#[repr(i8)] //~ ERROR: attribute should be applied to an enum
+struct SInt(f64, f64);
+
+#[repr(C)]
+enum EExtern { A, B }
+
+#[repr(align(8))]
+enum EAlign { A, B }
+
+#[repr(packed)] //~ ERROR: attribute should be applied to a struct
+enum EPacked { A, B }
+
+#[repr(simd)] //~ ERROR: attribute should be applied to a struct
+enum ESimd { A, B }
+
+#[repr(i8)]
+enum EInt { A, B }
+
+fn main() {}
diff --git a/tests/ui/repr/attr-usage-repr.stderr b/tests/ui/repr/attr-usage-repr.stderr
new file mode 100644
index 000000000..42f65625a
--- /dev/null
+++ b/tests/ui/repr/attr-usage-repr.stderr
@@ -0,0 +1,35 @@
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/attr-usage-repr.rs:3:8
+   |
+LL | #[repr(C)]
+   |        ^
+LL | fn f() {}
+   | --------- not a struct, enum, or union
+
+error[E0517]: attribute should be applied to an enum
+  --> $DIR/attr-usage-repr.rs:15:8
+   |
+LL | #[repr(i8)]
+   |        ^^
+LL | struct SInt(f64, f64);
+   | ---------------------- not an enum
+
+error[E0517]: attribute should be applied to a struct or union
+  --> $DIR/attr-usage-repr.rs:24:8
+   |
+LL | #[repr(packed)]
+   |        ^^^^^^
+LL | enum EPacked { A, B }
+   | --------------------- not a struct or union
+
+error[E0517]: attribute should be applied to a struct
+  --> $DIR/attr-usage-repr.rs:27:8
+   |
+LL | #[repr(simd)]
+   |        ^^^^
+LL | enum ESimd { A, B }
+   | ------------------- not a struct
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0517`.
diff --git a/tests/ui/repr/auxiliary/repr-transparent-non-exhaustive.rs b/tests/ui/repr/auxiliary/repr-transparent-non-exhaustive.rs
new file mode 100644
index 000000000..4bf6b54fe
--- /dev/null
+++ b/tests/ui/repr/auxiliary/repr-transparent-non-exhaustive.rs
@@ -0,0 +1,18 @@
+#![crate_type = "lib"]
+
+pub struct Private { _priv: () }
+
+#[non_exhaustive]
+pub struct NonExhaustive {}
+
+#[non_exhaustive]
+pub enum NonExhaustiveEnum {}
+
+pub enum NonExhaustiveVariant {
+    #[non_exhaustive]
+    A,
+}
+
+pub struct ExternalIndirection<T> {
+    pub x: T,
+}
diff --git a/tests/ui/repr/invalid_repr_list_help.rs b/tests/ui/repr/invalid_repr_list_help.rs
new file mode 100644
index 000000000..c32098453
--- /dev/null
+++ b/tests/ui/repr/invalid_repr_list_help.rs
@@ -0,0 +1,17 @@
+#![crate_type = "lib"]
+
+#[repr(uwu)] //~ERROR: unrecognized representation hint
+pub struct OwO;
+
+#[repr(uwu = "a")] //~ERROR: unrecognized representation hint
+pub struct OwO2(i32);
+
+#[repr(uwu(4))] //~ERROR: unrecognized representation hint
+pub struct OwO3 {
+    x: i32,
+}
+
+#[repr(uwu, u8)] //~ERROR: unrecognized representation hint
+pub enum OwO4 {
+    UwU = 1,
+}
diff --git a/tests/ui/repr/invalid_repr_list_help.stderr b/tests/ui/repr/invalid_repr_list_help.stderr
new file mode 100644
index 000000000..2acd56d9a
--- /dev/null
+++ b/tests/ui/repr/invalid_repr_list_help.stderr
@@ -0,0 +1,35 @@
+error[E0552]: unrecognized representation hint
+  --> $DIR/invalid_repr_list_help.rs:3:8
+   |
+LL | #[repr(uwu)]
+   |        ^^^
+   |
+   = help: valid reprs are `C`, `align`, `packed`, `transparent`, `simd`, `i8`, `u8`, `i16`, `u16`, `i32`, `u32`, `i64`, `u64`, `i128`, `u128`, `isize`, `usize`
+
+error[E0552]: unrecognized representation hint
+  --> $DIR/invalid_repr_list_help.rs:6:8
+   |
+LL | #[repr(uwu = "a")]
+   |        ^^^^^^^^^
+   |
+   = help: valid reprs are `C`, `align`, `packed`, `transparent`, `simd`, `i8`, `u8`, `i16`, `u16`, `i32`, `u32`, `i64`, `u64`, `i128`, `u128`, `isize`, `usize`
+
+error[E0552]: unrecognized representation hint
+  --> $DIR/invalid_repr_list_help.rs:9:8
+   |
+LL | #[repr(uwu(4))]
+   |        ^^^^^^
+   |
+   = help: valid reprs are `C`, `align`, `packed`, `transparent`, `simd`, `i8`, `u8`, `i16`, `u16`, `i32`, `u32`, `i64`, `u64`, `i128`, `u128`, `isize`, `usize`
+
+error[E0552]: unrecognized representation hint
+  --> $DIR/invalid_repr_list_help.rs:14:8
+   |
+LL | #[repr(uwu, u8)]
+   |        ^^^
+   |
+   = help: valid reprs are `C`, `align`, `packed`, `transparent`, `simd`, `i8`, `u8`, `i16`, `u16`, `i32`, `u32`, `i64`, `u64`, `i128`, `u128`, `isize`, `usize`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0552`.
diff --git a/tests/ui/repr/issue-83505-repr-simd.rs b/tests/ui/repr/issue-83505-repr-simd.rs
new file mode 100644
index 000000000..280b771d0
--- /dev/null
+++ b/tests/ui/repr/issue-83505-repr-simd.rs
@@ -0,0 +1,10 @@
+// Regression test for the ICE described in #83505.
+
+#![crate_type="lib"]
+
+#[repr(simd)]
+//~^ ERROR: attribute should be applied to a struct [E0517]
+//~| ERROR: unsupported representation for zero-variant enum [E0084]
+enum Es {}
+static CLs: Es;
+//~^ ERROR: free static item without body
diff --git a/tests/ui/repr/issue-83505-repr-simd.stderr b/tests/ui/repr/issue-83505-repr-simd.stderr
new file mode 100644
index 000000000..df99baaf5
--- /dev/null
+++ b/tests/ui/repr/issue-83505-repr-simd.stderr
@@ -0,0 +1,30 @@
+error: free static item without body
+  --> $DIR/issue-83505-repr-simd.rs:9:1
+   |
+LL | static CLs: Es;
+   | ^^^^^^^^^^^^^^-
+   |               |
+   |               help: provide a definition for the static: `= <expr>;`
+
+error[E0517]: attribute should be applied to a struct
+  --> $DIR/issue-83505-repr-simd.rs:5:8
+   |
+LL | #[repr(simd)]
+   |        ^^^^
+...
+LL | enum Es {}
+   | ---------- not a struct
+
+error[E0084]: unsupported representation for zero-variant enum
+  --> $DIR/issue-83505-repr-simd.rs:5:1
+   |
+LL | #[repr(simd)]
+   | ^^^^^^^^^^^^^
+...
+LL | enum Es {}
+   | ------- zero-variant enum
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0084, E0517.
+For more information about an error, try `rustc --explain E0084`.
diff --git a/tests/ui/repr/issue-83921-ice.rs b/tests/ui/repr/issue-83921-ice.rs
new file mode 100644
index 000000000..70583eb9b
--- /dev/null
+++ b/tests/ui/repr/issue-83921-ice.rs
@@ -0,0 +1,34 @@
+// Regression test for various ICEs inspired by
+// https://github.com/rust-lang/rust/issues/83921#issuecomment-814640734
+
+// compile-flags: -Zdeduplicate-diagnostics=yes
+
+#[repr(packed())]
+//~^ ERROR: incorrect `repr(packed)` attribute format
+struct S1;
+
+#[repr(align)]
+//~^ ERROR: invalid `repr(align)` attribute
+struct S2;
+
+#[repr(align(2, 4))]
+//~^ ERROR: incorrect `repr(align)` attribute format
+struct S3;
+
+#[repr(align())]
+//~^ ERROR: incorrect `repr(align)` attribute format
+struct S4;
+
+#[repr(i8())]
+//~^ ERROR: invalid representation hint
+enum E1 { A, B }
+
+#[repr(u32(42))]
+//~^ ERROR: invalid representation hint
+enum E2 { A, B }
+
+#[repr(i64 = 2)]
+//~^ ERROR: invalid representation hint
+enum E3 { A, B }
+
+fn main() {}
diff --git a/tests/ui/repr/issue-83921-ice.stderr b/tests/ui/repr/issue-83921-ice.stderr
new file mode 100644
index 000000000..32c450410
--- /dev/null
+++ b/tests/ui/repr/issue-83921-ice.stderr
@@ -0,0 +1,46 @@
+error[E0552]: incorrect `repr(packed)` attribute format: `packed` takes exactly one parenthesized argument, or no parentheses at all
+  --> $DIR/issue-83921-ice.rs:6:8
+   |
+LL | #[repr(packed())]
+   |        ^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: `align` needs an argument
+  --> $DIR/issue-83921-ice.rs:10:8
+   |
+LL | #[repr(align)]
+   |        ^^^^^ help: supply an argument here: `align(...)`
+
+error[E0693]: incorrect `repr(align)` attribute format: `align` takes exactly one argument in parentheses
+  --> $DIR/issue-83921-ice.rs:14:8
+   |
+LL | #[repr(align(2, 4))]
+   |        ^^^^^^^^^^^
+
+error[E0693]: incorrect `repr(align)` attribute format: `align` takes exactly one argument in parentheses
+  --> $DIR/issue-83921-ice.rs:18:8
+   |
+LL | #[repr(align())]
+   |        ^^^^^^^
+
+error[E0552]: invalid representation hint: `i8` does not take a parenthesized argument list
+  --> $DIR/issue-83921-ice.rs:22:8
+   |
+LL | #[repr(i8())]
+   |        ^^^^
+
+error[E0552]: invalid representation hint: `u32` does not take a parenthesized argument list
+  --> $DIR/issue-83921-ice.rs:26:8
+   |
+LL | #[repr(u32(42))]
+   |        ^^^^^^^
+
+error[E0552]: invalid representation hint: `i64` does not take a value
+  --> $DIR/issue-83921-ice.rs:30:8
+   |
+LL | #[repr(i64 = 2)]
+   |        ^^^^^^^
+
+error: aborting due to 7 previous errors
+
+Some errors have detailed explanations: E0552, E0589, E0693.
+For more information about an error, try `rustc --explain E0552`.
diff --git a/tests/ui/repr/repr-align-assign.fixed b/tests/ui/repr/repr-align-assign.fixed
new file mode 100644
index 000000000..59ca22e97
--- /dev/null
+++ b/tests/ui/repr/repr-align-assign.fixed
@@ -0,0 +1,13 @@
+// run-rustfix
+
+#![allow(dead_code)]
+
+#[repr(align(8))] //~ ERROR incorrect `repr(align)` attribute format
+                 //~| ERROR incorrect `repr(align)` attribute format
+struct A(u64);
+
+#[repr(align(8))] //~ ERROR incorrect `repr(align)` attribute format
+                   //~| ERROR incorrect `repr(align)` attribute format
+struct B(u64);
+
+fn main() {}
diff --git a/tests/ui/repr/repr-align-assign.rs b/tests/ui/repr/repr-align-assign.rs
new file mode 100644
index 000000000..6b7799297
--- /dev/null
+++ b/tests/ui/repr/repr-align-assign.rs
@@ -0,0 +1,13 @@
+// run-rustfix
+
+#![allow(dead_code)]
+
+#[repr(align=8)] //~ ERROR incorrect `repr(align)` attribute format
+                 //~| ERROR incorrect `repr(align)` attribute format
+struct A(u64);
+
+#[repr(align="8")] //~ ERROR incorrect `repr(align)` attribute format
+                   //~| ERROR incorrect `repr(align)` attribute format
+struct B(u64);
+
+fn main() {}
diff --git a/tests/ui/repr/repr-align-assign.stderr b/tests/ui/repr/repr-align-assign.stderr
new file mode 100644
index 000000000..b878ae0d1
--- /dev/null
+++ b/tests/ui/repr/repr-align-assign.stderr
@@ -0,0 +1,27 @@
+error[E0693]: incorrect `repr(align)` attribute format
+  --> $DIR/repr-align-assign.rs:5:8
+   |
+LL | #[repr(align=8)]
+   |        ^^^^^^^ help: use parentheses instead: `align(8)`
+
+error[E0693]: incorrect `repr(align)` attribute format
+  --> $DIR/repr-align-assign.rs:9:8
+   |
+LL | #[repr(align="8")]
+   |        ^^^^^^^^^ help: use parentheses instead: `align(8)`
+
+error[E0693]: incorrect `repr(align)` attribute format
+  --> $DIR/repr-align-assign.rs:5:8
+   |
+LL | #[repr(align=8)]
+   |        ^^^^^^^ help: use parentheses instead: `align(8)`
+
+error[E0693]: incorrect `repr(align)` attribute format
+  --> $DIR/repr-align-assign.rs:9:8
+   |
+LL | #[repr(align="8")]
+   |        ^^^^^^^^^ help: use parentheses instead: `align(8)`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0693`.
diff --git a/tests/ui/repr/repr-align.rs b/tests/ui/repr/repr-align.rs
new file mode 100644
index 000000000..58ecf9a51
--- /dev/null
+++ b/tests/ui/repr/repr-align.rs
@@ -0,0 +1,33 @@
+#![allow(dead_code)]
+
+#[repr(align(16.0))] //~ ERROR: invalid `repr(align)` attribute: not an unsuffixed integer
+                     //~| ERROR: invalid `repr(align)` attribute: not an unsuffixed integer
+struct S0(i32);
+
+#[repr(align(15))] //~ ERROR: invalid `repr(align)` attribute: not a power of two
+                   //~| ERROR: invalid `repr(align)` attribute: not a power of two
+struct S1(i32);
+
+#[repr(align(4294967296))] //~ ERROR: invalid `repr(align)` attribute: larger than 2^29
+                           //~| ERROR: invalid `repr(align)` attribute: larger than 2^29
+struct S2(i32);
+
+#[repr(align(536870912))] // ok: this is the largest accepted alignment
+struct S3(i32);
+
+#[repr(align(16.0))] //~ ERROR: invalid `repr(align)` attribute: not an unsuffixed integer
+                     //~| ERROR: invalid `repr(align)` attribute: not an unsuffixed integer
+enum E0 { A, B }
+
+#[repr(align(15))] //~ ERROR: invalid `repr(align)` attribute: not a power of two
+                   //~| ERROR: invalid `repr(align)` attribute: not a power of two
+enum E1 { A, B }
+
+#[repr(align(4294967296))] //~ ERROR: invalid `repr(align)` attribute: larger than 2^29
+                           //~| ERROR: invalid `repr(align)` attribute: larger than 2^29
+enum E2 { A, B }
+
+#[repr(align(536870912))] // ok: this is the largest accepted alignment
+enum E3 { A, B }
+
+fn main() {}
diff --git a/tests/ui/repr/repr-align.stderr b/tests/ui/repr/repr-align.stderr
new file mode 100644
index 000000000..900a811bb
--- /dev/null
+++ b/tests/ui/repr/repr-align.stderr
@@ -0,0 +1,75 @@
+error[E0589]: invalid `repr(align)` attribute: not an unsuffixed integer
+  --> $DIR/repr-align.rs:3:8
+   |
+LL | #[repr(align(16.0))]
+   |        ^^^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: not a power of two
+  --> $DIR/repr-align.rs:7:8
+   |
+LL | #[repr(align(15))]
+   |        ^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: larger than 2^29
+  --> $DIR/repr-align.rs:11:8
+   |
+LL | #[repr(align(4294967296))]
+   |        ^^^^^^^^^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: not an unsuffixed integer
+  --> $DIR/repr-align.rs:18:8
+   |
+LL | #[repr(align(16.0))]
+   |        ^^^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: not a power of two
+  --> $DIR/repr-align.rs:22:8
+   |
+LL | #[repr(align(15))]
+   |        ^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: larger than 2^29
+  --> $DIR/repr-align.rs:26:8
+   |
+LL | #[repr(align(4294967296))]
+   |        ^^^^^^^^^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: not an unsuffixed integer
+  --> $DIR/repr-align.rs:3:8
+   |
+LL | #[repr(align(16.0))]
+   |        ^^^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: not a power of two
+  --> $DIR/repr-align.rs:7:8
+   |
+LL | #[repr(align(15))]
+   |        ^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: larger than 2^29
+  --> $DIR/repr-align.rs:11:8
+   |
+LL | #[repr(align(4294967296))]
+   |        ^^^^^^^^^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: not an unsuffixed integer
+  --> $DIR/repr-align.rs:18:8
+   |
+LL | #[repr(align(16.0))]
+   |        ^^^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: not a power of two
+  --> $DIR/repr-align.rs:22:8
+   |
+LL | #[repr(align(15))]
+   |        ^^^^^^^^^
+
+error[E0589]: invalid `repr(align)` attribute: larger than 2^29
+  --> $DIR/repr-align.rs:26:8
+   |
+LL | #[repr(align(4294967296))]
+   |        ^^^^^^^^^^^^^^^^^
+
+error: aborting due to 12 previous errors
+
+For more information about this error, try `rustc --explain E0589`.
diff --git a/tests/ui/repr/repr-disallow-on-variant.rs b/tests/ui/repr/repr-disallow-on-variant.rs
new file mode 100644
index 000000000..d9bd0b0e3
--- /dev/null
+++ b/tests/ui/repr/repr-disallow-on-variant.rs
@@ -0,0 +1,9 @@
+struct Test;
+
+enum Foo {
+    #[repr(u8)]
+    //~^ ERROR attribute should be applied to an enum
+    Variant,
+}
+
+fn main() {}
diff --git a/tests/ui/repr/repr-disallow-on-variant.stderr b/tests/ui/repr/repr-disallow-on-variant.stderr
new file mode 100644
index 000000000..f7e4dcc9d
--- /dev/null
+++ b/tests/ui/repr/repr-disallow-on-variant.stderr
@@ -0,0 +1,12 @@
+error[E0517]: attribute should be applied to an enum
+  --> $DIR/repr-disallow-on-variant.rs:4:12
+   |
+LL |     #[repr(u8)]
+   |            ^^
+LL |
+LL |     Variant,
+   |     ------- not an enum
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0517`.
diff --git a/tests/ui/repr/repr-packed-contains-align.rs b/tests/ui/repr/repr-packed-contains-align.rs
new file mode 100644
index 000000000..bef5c7d8c
--- /dev/null
+++ b/tests/ui/repr/repr-packed-contains-align.rs
@@ -0,0 +1,53 @@
+#![allow(dead_code)]
+
+#[repr(align(16))]
+#[derive(Clone, Copy)]
+struct SA(i32);
+
+#[derive(Clone, Copy)]
+struct SB(SA);
+
+#[repr(align(16))]
+#[derive(Clone, Copy)]
+union UA {
+    i: i32
+}
+
+#[derive(Clone, Copy)]
+union UB {
+    a: UA
+}
+
+#[repr(packed)]
+struct SC(SA); //~ ERROR: packed type cannot transitively contain a `#[repr(align)]` type
+
+#[repr(packed)]
+struct SD(SB); //~ ERROR: packed type cannot transitively contain a `#[repr(align)]` type
+
+#[repr(packed)]
+struct SE(UA); //~ ERROR: packed type cannot transitively contain a `#[repr(align)]` type
+
+#[repr(packed)]
+struct SF(UB); //~ ERROR: packed type cannot transitively contain a `#[repr(align)]` type
+
+#[repr(packed)]
+union UC { //~ ERROR: packed type cannot transitively contain a `#[repr(align)]` type
+    a: UA
+}
+
+#[repr(packed)]
+union UD { //~ ERROR: packed type cannot transitively contain a `#[repr(align)]` type
+    n: UB
+}
+
+#[repr(packed)]
+union UE { //~ ERROR: packed type cannot transitively contain a `#[repr(align)]` type
+    a: SA
+}
+
+#[repr(packed)]
+union UF { //~ ERROR: packed type cannot transitively contain a `#[repr(align)]` type
+    n: SB
+}
+
+fn main() {}
diff --git a/tests/ui/repr/repr-packed-contains-align.stderr b/tests/ui/repr/repr-packed-contains-align.stderr
new file mode 100644
index 000000000..4c3a960ca
--- /dev/null
+++ b/tests/ui/repr/repr-packed-contains-align.stderr
@@ -0,0 +1,139 @@
+error[E0588]: packed type cannot transitively contain a `#[repr(align)]` type
+  --> $DIR/repr-packed-contains-align.rs:22:1
+   |
+LL | struct SC(SA);
+   | ^^^^^^^^^
+   |
+note: `SA` has a `#[repr(align)]` attribute
+  --> $DIR/repr-packed-contains-align.rs:5:1
+   |
+LL | struct SA(i32);
+   | ^^^^^^^^^
+
+error[E0588]: packed type cannot transitively contain a `#[repr(align)]` type
+  --> $DIR/repr-packed-contains-align.rs:25:1
+   |
+LL | struct SD(SB);
+   | ^^^^^^^^^
+   |
+note: `SA` has a `#[repr(align)]` attribute
+  --> $DIR/repr-packed-contains-align.rs:5:1
+   |
+LL | struct SA(i32);
+   | ^^^^^^^^^
+note: `SD` contains a field of type `SB`
+  --> $DIR/repr-packed-contains-align.rs:25:11
+   |
+LL | struct SD(SB);
+   |           ^^
+note: ...which contains a field of type `SA`
+  --> $DIR/repr-packed-contains-align.rs:8:11
+   |
+LL | struct SB(SA);
+   |           ^^
+
+error[E0588]: packed type cannot transitively contain a `#[repr(align)]` type
+  --> $DIR/repr-packed-contains-align.rs:28:1
+   |
+LL | struct SE(UA);
+   | ^^^^^^^^^
+   |
+note: `UA` has a `#[repr(align)]` attribute
+  --> $DIR/repr-packed-contains-align.rs:12:1
+   |
+LL | union UA {
+   | ^^^^^^^^
+
+error[E0588]: packed type cannot transitively contain a `#[repr(align)]` type
+  --> $DIR/repr-packed-contains-align.rs:31:1
+   |
+LL | struct SF(UB);
+   | ^^^^^^^^^
+   |
+note: `UA` has a `#[repr(align)]` attribute
+  --> $DIR/repr-packed-contains-align.rs:12:1
+   |
+LL | union UA {
+   | ^^^^^^^^
+note: `SF` contains a field of type `UB`
+  --> $DIR/repr-packed-contains-align.rs:31:11
+   |
+LL | struct SF(UB);
+   |           ^^
+note: ...which contains a field of type `UA`
+  --> $DIR/repr-packed-contains-align.rs:18:5
+   |
+LL |     a: UA
+   |     ^
+
+error[E0588]: packed type cannot transitively contain a `#[repr(align)]` type
+  --> $DIR/repr-packed-contains-align.rs:34:1
+   |
+LL | union UC {
+   | ^^^^^^^^
+   |
+note: `UA` has a `#[repr(align)]` attribute
+  --> $DIR/repr-packed-contains-align.rs:12:1
+   |
+LL | union UA {
+   | ^^^^^^^^
+
+error[E0588]: packed type cannot transitively contain a `#[repr(align)]` type
+  --> $DIR/repr-packed-contains-align.rs:39:1
+   |
+LL | union UD {
+   | ^^^^^^^^
+   |
+note: `UA` has a `#[repr(align)]` attribute
+  --> $DIR/repr-packed-contains-align.rs:12:1
+   |
+LL | union UA {
+   | ^^^^^^^^
+note: `UD` contains a field of type `UB`
+  --> $DIR/repr-packed-contains-align.rs:40:5
+   |
+LL |     n: UB
+   |     ^
+note: ...which contains a field of type `UA`
+  --> $DIR/repr-packed-contains-align.rs:18:5
+   |
+LL |     a: UA
+   |     ^
+
+error[E0588]: packed type cannot transitively contain a `#[repr(align)]` type
+  --> $DIR/repr-packed-contains-align.rs:44:1
+   |
+LL | union UE {
+   | ^^^^^^^^
+   |
+note: `SA` has a `#[repr(align)]` attribute
+  --> $DIR/repr-packed-contains-align.rs:5:1
+   |
+LL | struct SA(i32);
+   | ^^^^^^^^^
+
+error[E0588]: packed type cannot transitively contain a `#[repr(align)]` type
+  --> $DIR/repr-packed-contains-align.rs:49:1
+   |
+LL | union UF {
+   | ^^^^^^^^
+   |
+note: `SA` has a `#[repr(align)]` attribute
+  --> $DIR/repr-packed-contains-align.rs:5:1
+   |
+LL | struct SA(i32);
+   | ^^^^^^^^^
+note: `UF` contains a field of type `SB`
+  --> $DIR/repr-packed-contains-align.rs:50:5
+   |
+LL |     n: SB
+   |     ^
+note: ...which contains a field of type `SA`
+  --> $DIR/repr-packed-contains-align.rs:8:11
+   |
+LL | struct SB(SA);
+   |           ^^
+
+error: aborting due to 8 previous errors
+
+For more information about this error, try `rustc --explain E0588`.
diff --git a/tests/ui/repr/repr-transparent-issue-87496.rs b/tests/ui/repr/repr-transparent-issue-87496.rs
new file mode 100644
index 000000000..a4dd45c63
--- /dev/null
+++ b/tests/ui/repr/repr-transparent-issue-87496.rs
@@ -0,0 +1,12 @@
+// Regression test for the ICE described in #87496.
+
+// check-pass
+
+#[repr(transparent)]
+struct TransparentCustomZst(());
+extern "C" {
+    fn good17(p: TransparentCustomZst);
+    //~^ WARNING: `extern` block uses type `TransparentCustomZst`, which is not FFI-safe
+}
+
+fn main() {}
diff --git a/tests/ui/repr/repr-transparent-issue-87496.stderr b/tests/ui/repr/repr-transparent-issue-87496.stderr
new file mode 100644
index 000000000..aee31212b
--- /dev/null
+++ b/tests/ui/repr/repr-transparent-issue-87496.stderr
@@ -0,0 +1,16 @@
+warning: `extern` block uses type `TransparentCustomZst`, which is not FFI-safe
+  --> $DIR/repr-transparent-issue-87496.rs:8:18
+   |
+LL |     fn good17(p: TransparentCustomZst);
+   |                  ^^^^^^^^^^^^^^^^^^^^ not FFI-safe
+   |
+   = note: this struct contains only zero-sized fields
+note: the type is defined here
+  --> $DIR/repr-transparent-issue-87496.rs:6:1
+   |
+LL | struct TransparentCustomZst(());
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: `#[warn(improper_ctypes)]` on by default
+
+warning: 1 warning emitted
+
diff --git a/tests/ui/repr/repr-transparent-non-exhaustive.rs b/tests/ui/repr/repr-transparent-non-exhaustive.rs
new file mode 100644
index 000000000..506f1dcf3
--- /dev/null
+++ b/tests/ui/repr/repr-transparent-non-exhaustive.rs
@@ -0,0 +1,96 @@
+#![deny(repr_transparent_external_private_fields)]
+
+// aux-build: repr-transparent-non-exhaustive.rs
+extern crate repr_transparent_non_exhaustive;
+
+use repr_transparent_non_exhaustive::{
+    Private,
+    NonExhaustive,
+    NonExhaustiveEnum,
+    NonExhaustiveVariant,
+    ExternalIndirection,
+};
+
+pub struct InternalPrivate {
+    _priv: (),
+}
+
+#[non_exhaustive]
+pub struct InternalNonExhaustive;
+
+pub struct InternalIndirection<T> {
+    x: T,
+}
+
+pub type Sized = i32;
+
+#[repr(transparent)]
+pub struct T1(Sized, InternalPrivate);
+#[repr(transparent)]
+pub struct T2(Sized, InternalNonExhaustive);
+#[repr(transparent)]
+pub struct T3(Sized, InternalIndirection<(InternalPrivate, InternalNonExhaustive)>);
+#[repr(transparent)]
+pub struct T4(Sized, ExternalIndirection<(InternalPrivate, InternalNonExhaustive)>);
+
+#[repr(transparent)]
+pub struct T5(Sized, Private);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T6(Sized, NonExhaustive);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T7(Sized, NonExhaustiveEnum);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T8(Sized, NonExhaustiveVariant);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T9(Sized, InternalIndirection<Private>);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T10(Sized, InternalIndirection<NonExhaustive>);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T11(Sized, InternalIndirection<NonExhaustiveEnum>);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T12(Sized, InternalIndirection<NonExhaustiveVariant>);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T13(Sized, ExternalIndirection<Private>);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T14(Sized, ExternalIndirection<NonExhaustive>);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T15(Sized, ExternalIndirection<NonExhaustiveEnum>);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T16(Sized, ExternalIndirection<NonExhaustiveVariant>);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+fn main() {}
diff --git a/tests/ui/repr/repr-transparent-non-exhaustive.stderr b/tests/ui/repr/repr-transparent-non-exhaustive.stderr
new file mode 100644
index 000000000..16edf59c7
--- /dev/null
+++ b/tests/ui/repr/repr-transparent-non-exhaustive.stderr
@@ -0,0 +1,127 @@
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:37:22
+   |
+LL | pub struct T5(Sized, Private);
+   |                      ^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this struct contains `Private`, which contains private fields, and makes it not a breaking change to become non-zero-sized in the future.
+note: the lint level is defined here
+  --> $DIR/repr-transparent-non-exhaustive.rs:1:9
+   |
+LL | #![deny(repr_transparent_external_private_fields)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:42:22
+   |
+LL | pub struct T6(Sized, NonExhaustive);
+   |                      ^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this struct contains `NonExhaustive`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:47:22
+   |
+LL | pub struct T7(Sized, NonExhaustiveEnum);
+   |                      ^^^^^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this enum contains `NonExhaustiveEnum`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:52:22
+   |
+LL | pub struct T8(Sized, NonExhaustiveVariant);
+   |                      ^^^^^^^^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this enum contains `NonExhaustiveVariant`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:57:22
+   |
+LL | pub struct T9(Sized, InternalIndirection<Private>);
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this struct contains `Private`, which contains private fields, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:62:23
+   |
+LL | pub struct T10(Sized, InternalIndirection<NonExhaustive>);
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this struct contains `NonExhaustive`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:67:23
+   |
+LL | pub struct T11(Sized, InternalIndirection<NonExhaustiveEnum>);
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this enum contains `NonExhaustiveEnum`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:72:23
+   |
+LL | pub struct T12(Sized, InternalIndirection<NonExhaustiveVariant>);
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this enum contains `NonExhaustiveVariant`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:77:23
+   |
+LL | pub struct T13(Sized, ExternalIndirection<Private>);
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this struct contains `Private`, which contains private fields, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:82:23
+   |
+LL | pub struct T14(Sized, ExternalIndirection<NonExhaustive>);
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this struct contains `NonExhaustive`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:87:23
+   |
+LL | pub struct T15(Sized, ExternalIndirection<NonExhaustiveEnum>);
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this enum contains `NonExhaustiveEnum`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:92:23
+   |
+LL | pub struct T16(Sized, ExternalIndirection<NonExhaustiveVariant>);
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = 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 #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this enum contains `NonExhaustiveVariant`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: aborting due to 12 previous errors
+
diff --git a/tests/ui/repr/repr-transparent-other-items.rs b/tests/ui/repr/repr-transparent-other-items.rs
new file mode 100644
index 000000000..e537e3e1a
--- /dev/null
+++ b/tests/ui/repr/repr-transparent-other-items.rs
@@ -0,0 +1,9 @@
+// See also repr-transparent.rs
+
+#[repr(transparent)] //~ ERROR should be applied to a struct
+fn cant_repr_this() {}
+
+#[repr(transparent)] //~ ERROR should be applied to a struct
+static CANT_REPR_THIS: u32 = 0;
+
+fn main() {}
diff --git a/tests/ui/repr/repr-transparent-other-items.stderr b/tests/ui/repr/repr-transparent-other-items.stderr
new file mode 100644
index 000000000..14e6f13e1
--- /dev/null
+++ b/tests/ui/repr/repr-transparent-other-items.stderr
@@ -0,0 +1,19 @@
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/repr-transparent-other-items.rs:3:8
+   |
+LL | #[repr(transparent)]
+   |        ^^^^^^^^^^^
+LL | fn cant_repr_this() {}
+   | ---------------------- not a struct, enum, or union
+
+error[E0517]: attribute should be applied to a struct, enum, or union
+  --> $DIR/repr-transparent-other-items.rs:6:8
+   |
+LL | #[repr(transparent)]
+   |        ^^^^^^^^^^^
+LL | static CANT_REPR_THIS: u32 = 0;
+   | ------------------------------- not a struct, enum, or union
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0517`.
diff --git a/tests/ui/repr/repr-transparent-other-reprs.rs b/tests/ui/repr/repr-transparent-other-reprs.rs
new file mode 100644
index 000000000..0cd0edf32
--- /dev/null
+++ b/tests/ui/repr/repr-transparent-other-reprs.rs
@@ -0,0 +1,18 @@
+// See also repr-transparent.rs
+
+#[repr(transparent, C)] //~ ERROR cannot have other repr
+struct TransparentPlusC {
+    ptr: *const u8
+}
+
+#[repr(transparent, packed)] //~ ERROR cannot have other repr
+struct TransparentPlusPacked(*const u8);
+
+#[repr(transparent, align(2))] //~ ERROR cannot have other repr
+struct TransparentPlusAlign(u8);
+
+#[repr(transparent)] //~ ERROR cannot have other repr
+#[repr(C)]
+struct SeparateAttributes(*mut u8);
+
+fn main() {}
diff --git a/tests/ui/repr/repr-transparent-other-reprs.stderr b/tests/ui/repr/repr-transparent-other-reprs.stderr
new file mode 100644
index 000000000..d92c35811
--- /dev/null
+++ b/tests/ui/repr/repr-transparent-other-reprs.stderr
@@ -0,0 +1,29 @@
+error[E0692]: transparent struct cannot have other repr hints
+  --> $DIR/repr-transparent-other-reprs.rs:3:8
+   |
+LL | #[repr(transparent, C)]
+   |        ^^^^^^^^^^^  ^
+
+error[E0692]: transparent struct cannot have other repr hints
+  --> $DIR/repr-transparent-other-reprs.rs:8:8
+   |
+LL | #[repr(transparent, packed)]
+   |        ^^^^^^^^^^^  ^^^^^^
+
+error[E0692]: transparent struct cannot have other repr hints
+  --> $DIR/repr-transparent-other-reprs.rs:11:8
+   |
+LL | #[repr(transparent, align(2))]
+   |        ^^^^^^^^^^^  ^^^^^^^^
+
+error[E0692]: transparent struct cannot have other repr hints
+  --> $DIR/repr-transparent-other-reprs.rs:14:8
+   |
+LL | #[repr(transparent)]
+   |        ^^^^^^^^^^^
+LL | #[repr(C)]
+   |        ^
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0692`.
diff --git a/tests/ui/repr/repr-transparent.rs b/tests/ui/repr/repr-transparent.rs
new file mode 100644
index 000000000..8c9d1639c
--- /dev/null
+++ b/tests/ui/repr/repr-transparent.rs
@@ -0,0 +1,90 @@
+// This file tests repr(transparent)-related errors reported during typeck. Other errors
+// that are reported earlier and therefore preempt these are tested in:
+// - repr-transparent-other-reprs.rs
+// - repr-transparent-other-items.rs
+
+#![feature(transparent_unions)]
+
+use std::marker::PhantomData;
+
+#[repr(transparent)]
+struct NoFields;
+
+#[repr(transparent)]
+struct ContainsOnlyZst(());
+
+#[repr(transparent)]
+struct ContainsOnlyZstArray([bool; 0]);
+
+#[repr(transparent)]
+struct ContainsMultipleZst(PhantomData<*const i32>, NoFields);
+
+#[repr(transparent)]
+struct ContainsZstAndNonZst((), [i32; 2]);
+
+#[repr(transparent)]
+struct MultipleNonZst(u8, u8); //~ ERROR needs at most one non-zero-sized field
+
+trait Mirror { type It: ?Sized; }
+impl<T: ?Sized> Mirror for T { type It = Self; }
+
+#[repr(transparent)]
+pub struct StructWithProjection(f32, <f32 as Mirror>::It);
+//~^ ERROR needs at most one non-zero-sized field
+
+#[repr(transparent)]
+struct NontrivialAlignZst(u32, [u16; 0]); //~ ERROR alignment larger than 1
+
+#[repr(align(32))]
+struct ZstAlign32<T>(PhantomData<T>);
+
+#[repr(transparent)]
+struct GenericAlign<T>(ZstAlign32<T>, u32); //~ ERROR alignment larger than 1
+
+#[repr(transparent)] //~ ERROR unsupported representation for zero-variant enum
+enum Void {} //~ ERROR transparent enum needs exactly one variant, but has 0
+
+#[repr(transparent)]
+enum FieldlessEnum {
+    Foo,
+}
+
+#[repr(transparent)]
+enum UnitFieldEnum {
+    Foo(()),
+}
+
+#[repr(transparent)]
+enum TooManyFieldsEnum {
+    Foo(u32, String),
+}
+//~^^^ ERROR transparent enum needs at most one non-zero-sized field, but has 2
+
+#[repr(transparent)]
+enum MultipleVariants { //~ ERROR transparent enum needs exactly one variant, but has 2
+    Foo(String),
+    Bar,
+}
+
+#[repr(transparent)]
+enum NontrivialAlignZstEnum {
+    Foo(u32, [u16; 0]), //~ ERROR alignment larger than 1
+}
+
+#[repr(transparent)]
+enum GenericAlignEnum<T> {
+    Foo { bar: ZstAlign32<T>, baz: u32 } //~ ERROR alignment larger than 1
+}
+
+#[repr(transparent)]
+union UnitUnion {
+    u: (),
+}
+
+#[repr(transparent)]
+union TooManyFields { //~ ERROR transparent union needs at most one non-zero-sized field, but has 2
+    u: u32,
+    s: i32
+}
+
+fn main() {}
diff --git a/tests/ui/repr/repr-transparent.stderr b/tests/ui/repr/repr-transparent.stderr
new file mode 100644
index 000000000..f1c570b95
--- /dev/null
+++ b/tests/ui/repr/repr-transparent.stderr
@@ -0,0 +1,90 @@
+error[E0690]: transparent struct needs at most one non-zero-sized field, but has 2
+  --> $DIR/repr-transparent.rs:26:1
+   |
+LL | struct MultipleNonZst(u8, u8);
+   | ^^^^^^^^^^^^^^^^^^^^^ --  -- this field is non-zero-sized
+   | |                     |
+   | |                     this field is non-zero-sized
+   | needs at most one non-zero-sized field, but has 2
+
+error[E0690]: transparent struct needs at most one non-zero-sized field, but has 2
+  --> $DIR/repr-transparent.rs:32:1
+   |
+LL | pub struct StructWithProjection(f32, <f32 as Mirror>::It);
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ---  ------------------- this field is non-zero-sized
+   | |                               |
+   | |                               this field is non-zero-sized
+   | needs at most one non-zero-sized field, but has 2
+
+error[E0691]: zero-sized field in transparent struct has alignment larger than 1
+  --> $DIR/repr-transparent.rs:36:32
+   |
+LL | struct NontrivialAlignZst(u32, [u16; 0]);
+   |                                ^^^^^^^^ has alignment larger than 1
+
+error[E0691]: zero-sized field in transparent struct has alignment larger than 1
+  --> $DIR/repr-transparent.rs:42:24
+   |
+LL | struct GenericAlign<T>(ZstAlign32<T>, u32);
+   |                        ^^^^^^^^^^^^^ has alignment larger than 1
+
+error[E0084]: unsupported representation for zero-variant enum
+  --> $DIR/repr-transparent.rs:44:1
+   |
+LL | #[repr(transparent)]
+   | ^^^^^^^^^^^^^^^^^^^^
+LL | enum Void {}
+   | --------- zero-variant enum
+
+error[E0731]: transparent enum needs exactly one variant, but has 0
+  --> $DIR/repr-transparent.rs:45:1
+   |
+LL | enum Void {}
+   | ^^^^^^^^^ needs exactly one variant, but has 0
+
+error[E0690]: the variant of a transparent enum needs at most one non-zero-sized field, but has 2
+  --> $DIR/repr-transparent.rs:58:1
+   |
+LL | enum TooManyFieldsEnum {
+   | ^^^^^^^^^^^^^^^^^^^^^^ needs at most one non-zero-sized field, but has 2
+LL |     Foo(u32, String),
+   |         ---  ------ this field is non-zero-sized
+   |         |
+   |         this field is non-zero-sized
+
+error[E0731]: transparent enum needs exactly one variant, but has 2
+  --> $DIR/repr-transparent.rs:64:1
+   |
+LL | enum MultipleVariants {
+   | ^^^^^^^^^^^^^^^^^^^^^ needs exactly one variant, but has 2
+LL |     Foo(String),
+   |     ---
+LL |     Bar,
+   |     --- too many variants in `MultipleVariants`
+
+error[E0691]: zero-sized field in transparent enum has alignment larger than 1
+  --> $DIR/repr-transparent.rs:71:14
+   |
+LL |     Foo(u32, [u16; 0]),
+   |              ^^^^^^^^ has alignment larger than 1
+
+error[E0691]: zero-sized field in transparent enum has alignment larger than 1
+  --> $DIR/repr-transparent.rs:76:11
+   |
+LL |     Foo { bar: ZstAlign32<T>, baz: u32 }
+   |           ^^^^^^^^^^^^^^^^^^ has alignment larger than 1
+
+error[E0690]: transparent union needs at most one non-zero-sized field, but has 2
+  --> $DIR/repr-transparent.rs:85:1
+   |
+LL | union TooManyFields {
+   | ^^^^^^^^^^^^^^^^^^^ needs at most one non-zero-sized field, but has 2
+LL |     u: u32,
+   |     ------ this field is non-zero-sized
+LL |     s: i32
+   |     ------ this field is non-zero-sized
+
+error: aborting due to 11 previous errors
+
+Some errors have detailed explanations: E0084, E0690, E0691, E0731.
+For more information about an error, try `rustc --explain E0084`.
diff --git a/tests/ui/repr/repr.rs b/tests/ui/repr/repr.rs
new file mode 100644
index 000000000..564d67326
--- /dev/null
+++ b/tests/ui/repr/repr.rs
@@ -0,0 +1,13 @@
+#[repr] //~ ERROR malformed `repr` attribute
+struct _A {}
+
+#[repr = "B"] //~ ERROR malformed `repr` attribute
+struct _B {}
+
+#[repr = "C"] //~ ERROR malformed `repr` attribute
+struct _C {}
+
+#[repr(C)]
+struct _D {}
+
+fn main() {}
diff --git a/tests/ui/repr/repr.stderr b/tests/ui/repr/repr.stderr
new file mode 100644
index 000000000..e0bec6663
--- /dev/null
+++ b/tests/ui/repr/repr.stderr
@@ -0,0 +1,20 @@
+error: malformed `repr` attribute input
+  --> $DIR/repr.rs:1:1
+   |
+LL | #[repr]
+   | ^^^^^^^ help: must be of the form: `#[repr(C)]`
+
+error: malformed `repr` attribute input
+  --> $DIR/repr.rs:4:1
+   |
+LL | #[repr = "B"]
+   | ^^^^^^^^^^^^^ help: must be of the form: `#[repr(C)]`
+
+error: malformed `repr` attribute input
+  --> $DIR/repr.rs:7:1
+   |
+LL | #[repr = "C"]
+   | ^^^^^^^^^^^^^ help: must be of the form: `#[repr(C)]`
+
+error: aborting due to 3 previous errors
+
diff --git a/tests/ui/repr/repr_c_int_align.rs b/tests/ui/repr/repr_c_int_align.rs
new file mode 100644
index 000000000..fdd14fc2d
--- /dev/null
+++ b/tests/ui/repr/repr_c_int_align.rs
@@ -0,0 +1,46 @@
+// run-pass
+// compile-flags: -O
+
+#![allow(dead_code)]
+
+#[repr(C, u8)]
+enum ReprCu8 {
+    A(u16),
+    B,
+}
+
+#[repr(u8)]
+enum Repru8 {
+    A(u16),
+    B,
+}
+
+#[repr(C)]
+struct ReprC {
+    tag: u8,
+    padding: u8,
+    payload: u16,
+}
+
+fn main() {
+    // Test `repr(C, u8)`.
+    let r1 = ReprC { tag: 0, padding: 0, payload: 0 };
+    let r2 = ReprC { tag: 0, padding: 1, payload: 1 };
+
+    let t1: &ReprCu8 = unsafe { std::mem::transmute(&r1) };
+    let t2: &ReprCu8 = unsafe { std::mem::transmute(&r2) };
+
+    match (t1, t2) {
+        (ReprCu8::A(_), ReprCu8::A(_)) => (),
+        _ => assert!(false)
+    };
+
+    // Test `repr(u8)`.
+    let t1: &Repru8 = unsafe { std::mem::transmute(&r1) };
+    let t2: &Repru8 = unsafe { std::mem::transmute(&r2) };
+
+    match (t1, t2) {
+        (Repru8::A(_), Repru8::A(_)) => (),
+        _ => assert!(false)
+    };
+}
diff --git a/tests/ui/repr/transparent-enum-too-many-variants.rs b/tests/ui/repr/transparent-enum-too-many-variants.rs
new file mode 100644
index 000000000..0dd4b4e68
--- /dev/null
+++ b/tests/ui/repr/transparent-enum-too-many-variants.rs
@@ -0,0 +1,10 @@
+use std::mem::size_of;
+
+#[repr(transparent)]
+enum Foo { //~ ERROR E0731
+    A(u8), B(u8),
+}
+
+fn main() {
+    println!("Foo: {}", size_of::<Foo>());
+}
diff --git a/tests/ui/repr/transparent-enum-too-many-variants.stderr b/tests/ui/repr/transparent-enum-too-many-variants.stderr
new file mode 100644
index 000000000..fb44757ef
--- /dev/null
+++ b/tests/ui/repr/transparent-enum-too-many-variants.stderr
@@ -0,0 +1,11 @@
+error[E0731]: transparent enum needs exactly one variant, but has 2
+  --> $DIR/transparent-enum-too-many-variants.rs:4:1
+   |
+LL | enum Foo {
+   | ^^^^^^^^ needs exactly one variant, but has 2
+LL |     A(u8), B(u8),
+   |     -      - too many variants in `Foo`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0731`.