Merging upstream version 1.68.2+dfsg1.

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

5 files changed, 483 insertions, 0 deletions

diff --git a/tests/ui/transmutability/structs/repr/should_handle_align.rs b/tests/ui/transmutability/structs/repr/should_handle_align.rs
new file mode 100644
index 000000000..ea9bf2a23
--- /dev/null
+++ b/tests/ui/transmutability/structs/repr/should_handle_align.rs
@@ -0,0 +1,43 @@
+// check-pass
+//! The presence of an `align(X)` annotation must be accounted for.
+
+#![crate_type = "lib"]
+#![feature(transmutability)]
+#![allow(dead_code, incomplete_features, non_camel_case_types)]
+
+mod assert {
+    use std::mem::{Assume, BikeshedIntrinsicFrom};
+    pub struct Context;
+
+    pub fn is_maybe_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, {
+            Assume {
+                alignment: true,
+                lifetimes: true,
+                safety: true,
+                validity: true,
+            }
+        }>
+    {}
+}
+
+fn should_pad_explicitly_aligned_field() {
+    #[derive(Clone, Copy)] #[repr(u8)] enum V0u8 { V = 0 }
+
+    #[repr(C)]
+    pub union Uninit {
+        a: (),
+        b: V0u8,
+    }
+
+    #[repr(C, align(2))] struct align_2(V0u8);
+
+    #[repr(C)] struct ImplicitlyPadded(align_2, V0u8);
+    #[repr(C)] struct ExplicitlyPadded(V0u8, Uninit, V0u8);
+
+    // An implementation that (incorrectly) does not place a padding byte after
+    // `align_2` will, incorrectly, reject the following transmutations.
+    assert::is_maybe_transmutable::<ImplicitlyPadded, ExplicitlyPadded>();
+    assert::is_maybe_transmutable::<ExplicitlyPadded, ImplicitlyPadded>();
+}
diff --git a/tests/ui/transmutability/structs/repr/should_handle_packed.rs b/tests/ui/transmutability/structs/repr/should_handle_packed.rs
new file mode 100644
index 000000000..17dc995fc
--- /dev/null
+++ b/tests/ui/transmutability/structs/repr/should_handle_packed.rs
@@ -0,0 +1,42 @@
+// check-pass
+//! The presence of an `align(X)` annotation must be accounted for.
+
+#![crate_type = "lib"]
+#![feature(transmutability)]
+#![allow(dead_code, incomplete_features, non_camel_case_types)]
+
+mod assert {
+    use std::mem::{Assume, BikeshedIntrinsicFrom};
+    pub struct Context;
+
+    pub fn is_maybe_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, {
+            Assume {
+                alignment: true,
+                lifetimes: true,
+                safety: true,
+                validity: true,
+            }
+        }>
+    {}
+}
+
+fn should_pad_explicitly_packed_field() {
+    #[derive(Clone, Copy)] #[repr(u8)] enum V0u8 { V = 0 }
+    #[derive(Clone, Copy)] #[repr(u32)] enum V0u32 { V = 0 }
+
+    #[repr(C)]
+    pub union Uninit {
+        a: (),
+        b: V0u8,
+    }
+
+    #[repr(C, packed(2))] struct ImplicitlyPadded(V0u8, V0u32);
+    #[repr(C)] struct ExplicitlyPadded(V0u8, Uninit, V0u8, V0u8, V0u8, V0u8);
+
+    // An implementation that (incorrectly) does not place a padding byte after
+    // `align_2` will, incorrectly, reject the following transmutations.
+    assert::is_maybe_transmutable::<ImplicitlyPadded, ExplicitlyPadded>();
+    assert::is_maybe_transmutable::<ExplicitlyPadded, ImplicitlyPadded>();
+}
diff --git a/tests/ui/transmutability/structs/repr/should_require_well_defined_layout.rs b/tests/ui/transmutability/structs/repr/should_require_well_defined_layout.rs
new file mode 100644
index 000000000..9a65b4d70
--- /dev/null
+++ b/tests/ui/transmutability/structs/repr/should_require_well_defined_layout.rs
@@ -0,0 +1,83 @@
+//! A struct must have a well-defined layout to participate in a transmutation.
+
+#![crate_type = "lib"]
+#![feature(transmutability)]
+#![allow(dead_code, incomplete_features, non_camel_case_types)]
+
+mod assert {
+    use std::mem::{Assume, BikeshedIntrinsicFrom};
+    pub struct Context;
+
+    pub fn is_maybe_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, {
+            Assume {
+                alignment: true,
+                lifetimes: true,
+                safety: true,
+                validity: true,
+            }
+        }>
+    {}
+}
+
+fn should_reject_repr_rust()
+{
+    fn unit() {
+        struct repr_rust;
+        assert::is_maybe_transmutable::<repr_rust, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_rust>(); //~ ERROR cannot be safely transmuted
+    }
+
+    fn tuple() {
+        struct repr_rust();
+        assert::is_maybe_transmutable::<repr_rust, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_rust>(); //~ ERROR cannot be safely transmuted
+    }
+
+    fn braces() {
+        struct repr_rust{}
+        assert::is_maybe_transmutable::<repr_rust, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_rust>(); //~ ERROR cannot be safely transmuted
+    }
+
+    fn aligned() {
+        #[repr(align(1))] struct repr_rust{}
+        assert::is_maybe_transmutable::<repr_rust, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_rust>(); //~ ERROR cannot be safely transmuted
+    }
+
+    fn packed() {
+        #[repr(packed)] struct repr_rust{}
+        assert::is_maybe_transmutable::<repr_rust, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_rust>(); //~ ERROR cannot be safely transmuted
+    }
+
+    fn nested() {
+        struct repr_rust;
+        #[repr(C)] struct repr_c(repr_rust);
+        assert::is_maybe_transmutable::<repr_c, ()>(); //~ ERROR cannot be safely transmuted
+        assert::is_maybe_transmutable::<u128, repr_c>(); //~ ERROR cannot be safely transmuted
+    }
+}
+
+fn should_accept_repr_C()
+{
+    fn unit() {
+        #[repr(C)] struct repr_c;
+        assert::is_maybe_transmutable::<repr_c, ()>();
+        assert::is_maybe_transmutable::<i128, repr_c>();
+    }
+
+    fn tuple() {
+        #[repr(C)] struct repr_c();
+        assert::is_maybe_transmutable::<repr_c, ()>();
+        assert::is_maybe_transmutable::<i128, repr_c>();
+    }
+
+    fn braces() {
+        #[repr(C)] struct repr_c{}
+        assert::is_maybe_transmutable::<repr_c, ()>();
+        assert::is_maybe_transmutable::<i128, repr_c>();
+    }
+}
diff --git a/tests/ui/transmutability/structs/repr/should_require_well_defined_layout.stderr b/tests/ui/transmutability/structs/repr/should_require_well_defined_layout.stderr
new file mode 100644
index 000000000..621dbee84
--- /dev/null
+++ b/tests/ui/transmutability/structs/repr/should_require_well_defined_layout.stderr
@@ -0,0 +1,279 @@
+error[E0277]: `should_reject_repr_rust::unit::repr_rust` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:28:52
+   |
+LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
+   |                                                    ^^ `should_reject_repr_rust::unit::repr_rust` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<should_reject_repr_rust::unit::repr_rust, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `()`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::unit::repr_rust` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:29:47
+   |
+LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
+   |                                               ^^^^^^^^^ `u128` cannot be safely transmuted into `should_reject_repr_rust::unit::repr_rust` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u128, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `should_reject_repr_rust::unit::repr_rust`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `should_reject_repr_rust::tuple::repr_rust` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:34:52
+   |
+LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
+   |                                                    ^^ `should_reject_repr_rust::tuple::repr_rust` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<should_reject_repr_rust::tuple::repr_rust, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `()`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::tuple::repr_rust` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:35:47
+   |
+LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
+   |                                               ^^^^^^^^^ `u128` cannot be safely transmuted into `should_reject_repr_rust::tuple::repr_rust` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u128, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `should_reject_repr_rust::tuple::repr_rust`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `should_reject_repr_rust::braces::repr_rust` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:40:52
+   |
+LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
+   |                                                    ^^ `should_reject_repr_rust::braces::repr_rust` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<should_reject_repr_rust::braces::repr_rust, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `()`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::braces::repr_rust` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:41:47
+   |
+LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
+   |                                               ^^^^^^^^^ `u128` cannot be safely transmuted into `should_reject_repr_rust::braces::repr_rust` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u128, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `should_reject_repr_rust::braces::repr_rust`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `aligned::repr_rust` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:46:52
+   |
+LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
+   |                                                    ^^ `aligned::repr_rust` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<aligned::repr_rust, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `()`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `u128` cannot be safely transmuted into `aligned::repr_rust` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:47:47
+   |
+LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
+   |                                               ^^^^^^^^^ `u128` cannot be safely transmuted into `aligned::repr_rust` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u128, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `aligned::repr_rust`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `packed::repr_rust` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:52:52
+   |
+LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
+   |                                                    ^^ `packed::repr_rust` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<packed::repr_rust, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `()`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `u128` cannot be safely transmuted into `packed::repr_rust` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:53:47
+   |
+LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
+   |                                               ^^^^^^^^^ `u128` cannot be safely transmuted into `packed::repr_rust` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u128, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `packed::repr_rust`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `nested::repr_c` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:59:49
+   |
+LL |         assert::is_maybe_transmutable::<repr_c, ()>();
+   |                                                 ^^ `nested::repr_c` cannot be safely transmuted into `()` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<nested::repr_c, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `()`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error[E0277]: `u128` cannot be safely transmuted into `nested::repr_c` in the defining scope of `assert::Context`.
+  --> $DIR/should_require_well_defined_layout.rs:60:47
+   |
+LL |         assert::is_maybe_transmutable::<u128, repr_c>();
+   |                                               ^^^^^^ `u128` cannot be safely transmuted into `nested::repr_c` in the defining scope of `assert::Context`.
+   |
+   = help: the trait `BikeshedIntrinsicFrom<u128, assert::Context, Assume { alignment: true, lifetimes: true, safety: true, validity: true }>` is not implemented for `nested::repr_c`
+note: required by a bound in `is_maybe_transmutable`
+  --> $DIR/should_require_well_defined_layout.rs:13:14
+   |
+LL |       pub fn is_maybe_transmutable<Src, Dst>()
+   |              --------------------- required by a bound in this
+LL |       where
+LL |           Dst: BikeshedIntrinsicFrom<Src, Context, {
+   |  ______________^
+LL | |             Assume {
+LL | |                 alignment: true,
+LL | |                 lifetimes: true,
+...  |
+LL | |             }
+LL | |         }>
+   | |__________^ required by this bound in `is_maybe_transmutable`
+
+error: aborting due to 12 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/transmutability/structs/should_order_fields_correctly.rs b/tests/ui/transmutability/structs/should_order_fields_correctly.rs
new file mode 100644
index 000000000..28724562b
--- /dev/null
+++ b/tests/ui/transmutability/structs/should_order_fields_correctly.rs
@@ -0,0 +1,36 @@
+// check-pass
+//! The fields of a struct should be laid out in lexical order.
+
+#![crate_type = "lib"]
+#![feature(transmutability)]
+#![allow(dead_code)]
+
+mod assert {
+    use std::mem::{Assume, BikeshedIntrinsicFrom};
+    pub struct Context;
+
+    pub fn is_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, {
+            Assume::ALIGNMENT
+                .and(Assume::LIFETIMES)
+                .and(Assume::SAFETY)
+                .and(Assume::VALIDITY)
+        }>
+    {}
+}
+
+#[repr(u8)] enum V0 { V = 0 }
+#[repr(u8)] enum V1 { V = 1 }
+#[repr(u8)] enum V2 { V = 2 }
+
+#[repr(C)] struct S01(V0, V1);
+#[repr(C)] struct S012(V0, V1, V2);
+
+fn should_order_tag_and_fields_correctly() {
+    // An implementation that (incorrectly) arranges S01 as [0x01, 0x00] will,
+    // in principle, reject this transmutation.
+    assert::is_transmutable::<S01, V0>();
+    // Again, but with one more field.
+    assert::is_transmutable::<S012, S01>();
+}