Safe Transmute: Use 'not yet supported', not 'unspecified' in errors

We can (and will) support analyzing the transmutability of types
whose layouts aren't completely specified by its repr. This change
ensures that the error messages remain sensible after this support
lands.

8 files changed, 43 insertions, 43 deletions

diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
index b85a05c774f..e060803c1cb 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
@@ -3073,12 +3073,12 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 let src = trait_ref.args.type_at(1);
                 let err_msg = format!("`{src}` cannot be safely transmuted into `{dst}`");
                 let safe_transmute_explanation = match reason {
-                    rustc_transmute::Reason::SrcIsUnspecified => {
-                        format!("`{src}` does not have a well-specified layout")
+                    rustc_transmute::Reason::SrcIsNotYetSupported => {
+                        format!("analyzing the transmutability of `{src}` is not yet supported.")
                     }
 
-                    rustc_transmute::Reason::DstIsUnspecified => {
-                        format!("`{dst}` does not have a well-specified layout")
+                    rustc_transmute::Reason::DstIsNotYetSupported => {
+                        format!("analyzing the transmutability of `{dst}` is not yet supported.")
                     }
 
                     rustc_transmute::Reason::DstIsBitIncompatible => {
diff --git a/compiler/rustc_transmute/src/layout/tree.rs b/compiler/rustc_transmute/src/layout/tree.rs
index c2fc55542ff..9a43d67d435 100644
--- a/compiler/rustc_transmute/src/layout/tree.rs
+++ b/compiler/rustc_transmute/src/layout/tree.rs
@@ -186,8 +186,8 @@ pub(crate) mod rustc {
 
     #[derive(Debug, Copy, Clone)]
     pub(crate) enum Err {
-        /// The layout of the type is unspecified.
-        Unspecified,
+        /// The layout of the type is not yet supported.
+        NotYetSupported,
         /// This error will be surfaced elsewhere by rustc, so don't surface it.
         UnknownLayout,
         /// Overflow size
@@ -288,14 +288,14 @@ pub(crate) mod rustc {
                     if members.len() == 0 {
                         Ok(Tree::unit())
                     } else {
-                        Err(Err::Unspecified)
+                        Err(Err::NotYetSupported)
                     }
                 }
 
                 ty::Array(ty, len) => {
                     let len = len
                         .try_eval_target_usize(tcx, ParamEnv::reveal_all())
-                        .ok_or(Err::Unspecified)?;
+                        .ok_or(Err::NotYetSupported)?;
                     let elt = Tree::from_ty(*ty, tcx)?;
                     Ok(std::iter::repeat(elt)
                         .take(len as usize)
@@ -307,7 +307,7 @@ pub(crate) mod rustc {
 
                     // If the layout is ill-specified, halt.
                     if !(adt_def.repr().c() || adt_def.repr().int.is_some()) {
-                        return Err(Err::Unspecified);
+                        return Err(Err::NotYetSupported);
                     }
 
                     // Compute a summary of the type's layout.
@@ -348,7 +348,7 @@ pub(crate) mod rustc {
                         AdtKind::Union => {
                             // is the layout well-defined?
                             if !adt_def.repr().c() {
-                                return Err(Err::Unspecified);
+                                return Err(Err::NotYetSupported);
                             }
 
                             let ty_layout = layout_of(tcx, ty)?;
@@ -384,7 +384,7 @@ pub(crate) mod rustc {
                     }))
                 }
 
-                _ => Err(Err::Unspecified),
+                _ => Err(Err::NotYetSupported),
             }
         }
 
diff --git a/compiler/rustc_transmute/src/lib.rs b/compiler/rustc_transmute/src/lib.rs
index 8f3af491453..e871c4659b4 100644
--- a/compiler/rustc_transmute/src/lib.rs
+++ b/compiler/rustc_transmute/src/lib.rs
@@ -43,10 +43,10 @@ pub enum Condition<R> {
 /// Answers "why wasn't the source type transmutable into the destination type?"
 #[derive(Debug, Hash, Eq, PartialEq, PartialOrd, Ord, Clone)]
 pub enum Reason<T> {
-    /// The layout of the source type is unspecified.
-    SrcIsUnspecified,
-    /// The layout of the destination type is unspecified.
-    DstIsUnspecified,
+    /// The layout of the source type is not yet supported.
+    SrcIsNotYetSupported,
+    /// The layout of the destination type is not yet supported.
+    DstIsNotYetSupported,
     /// The layout of the destination type is bit-incompatible with the source type.
     DstIsBitIncompatible,
     /// The destination type may carry safety invariants.
diff --git a/compiler/rustc_transmute/src/maybe_transmutable/mod.rs b/compiler/rustc_transmute/src/maybe_transmutable/mod.rs
index e9f425686c4..16d15580a05 100644
--- a/compiler/rustc_transmute/src/maybe_transmutable/mod.rs
+++ b/compiler/rustc_transmute/src/maybe_transmutable/mod.rs
@@ -56,8 +56,8 @@ mod rustc {
                 }
                 (Err(Err::UnknownLayout), _) => Answer::No(Reason::SrcLayoutUnknown),
                 (_, Err(Err::UnknownLayout)) => Answer::No(Reason::DstLayoutUnknown),
-                (Err(Err::Unspecified), _) => Answer::No(Reason::SrcIsUnspecified),
-                (_, Err(Err::Unspecified)) => Answer::No(Reason::DstIsUnspecified),
+                (Err(Err::NotYetSupported), _) => Answer::No(Reason::SrcIsNotYetSupported),
+                (_, Err(Err::NotYetSupported)) => Answer::No(Reason::DstIsNotYetSupported),
                 (Err(Err::SizeOverflow), _) => Answer::No(Reason::SrcSizeOverflow),
                 (_, Err(Err::SizeOverflow)) => Answer::No(Reason::DstSizeOverflow),
                 (Ok(src), Ok(dst)) => MaybeTransmutableQuery { src, dst, assume, context }.answer(),
diff --git a/tests/ui/transmutability/arrays/should_require_well_defined_layout.stderr b/tests/ui/transmutability/arrays/should_require_well_defined_layout.stderr
index fd21ac34183..e486928a445 100644
--- a/tests/ui/transmutability/arrays/should_require_well_defined_layout.stderr
+++ b/tests/ui/transmutability/arrays/should_require_well_defined_layout.stderr
@@ -2,7 +2,7 @@ error[E0277]: `[String; 0]` cannot be safely transmuted into `()`
   --> $DIR/should_require_well_defined_layout.rs:25:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `[String; 0]` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `[String; 0]` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -23,7 +23,7 @@ error[E0277]: `u128` cannot be safely transmuted into `[String; 0]`
   --> $DIR/should_require_well_defined_layout.rs:26:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `[String; 0]` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `[String; 0]` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -44,7 +44,7 @@ error[E0277]: `[String; 1]` cannot be safely transmuted into `()`
   --> $DIR/should_require_well_defined_layout.rs:31:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `[String; 1]` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `[String; 1]` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -65,7 +65,7 @@ error[E0277]: `u128` cannot be safely transmuted into `[String; 1]`
   --> $DIR/should_require_well_defined_layout.rs:32:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `[String; 1]` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `[String; 1]` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -86,7 +86,7 @@ error[E0277]: `[String; 2]` cannot be safely transmuted into `()`
   --> $DIR/should_require_well_defined_layout.rs:37:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `[String; 2]` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `[String; 2]` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -107,7 +107,7 @@ error[E0277]: `u128` cannot be safely transmuted into `[String; 2]`
   --> $DIR/should_require_well_defined_layout.rs:38:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `[String; 2]` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `[String; 2]` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
diff --git a/tests/ui/transmutability/enums/repr/should_require_well_defined_layout.stderr b/tests/ui/transmutability/enums/repr/should_require_well_defined_layout.stderr
index 24730935047..2a683de6a65 100644
--- a/tests/ui/transmutability/enums/repr/should_require_well_defined_layout.stderr
+++ b/tests/ui/transmutability/enums/repr/should_require_well_defined_layout.stderr
@@ -2,7 +2,7 @@ error[E0277]: `void::repr_rust` cannot be safely transmuted into `()`
   --> $DIR/should_require_well_defined_layout.rs:27:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `void::repr_rust` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `void::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:13:14
@@ -24,7 +24,7 @@ error[E0277]: `u128` cannot be safely transmuted into `void::repr_rust`
   --> $DIR/should_require_well_defined_layout.rs:28:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `void::repr_rust` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `void::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:13:14
@@ -46,7 +46,7 @@ error[E0277]: `singleton::repr_rust` cannot be safely transmuted into `()`
   --> $DIR/should_require_well_defined_layout.rs:33:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `singleton::repr_rust` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `singleton::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:13:14
@@ -68,7 +68,7 @@ error[E0277]: `u128` cannot be safely transmuted into `singleton::repr_rust`
   --> $DIR/should_require_well_defined_layout.rs:34:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `singleton::repr_rust` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `singleton::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:13:14
@@ -90,7 +90,7 @@ error[E0277]: `duplex::repr_rust` cannot be safely transmuted into `()`
   --> $DIR/should_require_well_defined_layout.rs:39:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `duplex::repr_rust` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `duplex::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:13:14
@@ -112,7 +112,7 @@ error[E0277]: `u128` cannot be safely transmuted into `duplex::repr_rust`
   --> $DIR/should_require_well_defined_layout.rs:40:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `duplex::repr_rust` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `duplex::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:13:14
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
index 924422de538..77788f72c21 100644
--- a/tests/ui/transmutability/structs/repr/should_require_well_defined_layout.stderr
+++ b/tests/ui/transmutability/structs/repr/should_require_well_defined_layout.stderr
@@ -2,7 +2,7 @@ error[E0277]: `should_reject_repr_rust::unit::repr_rust` cannot be safely transm
   --> $DIR/should_require_well_defined_layout.rs:27:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `should_reject_repr_rust::unit::repr_rust` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `should_reject_repr_rust::unit::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -24,7 +24,7 @@ error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::
   --> $DIR/should_require_well_defined_layout.rs:28:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `should_reject_repr_rust::unit::repr_rust` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `should_reject_repr_rust::unit::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -46,7 +46,7 @@ error[E0277]: `should_reject_repr_rust::tuple::repr_rust` cannot be safely trans
   --> $DIR/should_require_well_defined_layout.rs:33:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `should_reject_repr_rust::tuple::repr_rust` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `should_reject_repr_rust::tuple::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -68,7 +68,7 @@ error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::
   --> $DIR/should_require_well_defined_layout.rs:34:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `should_reject_repr_rust::tuple::repr_rust` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `should_reject_repr_rust::tuple::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -90,7 +90,7 @@ error[E0277]: `should_reject_repr_rust::braces::repr_rust` cannot be safely tran
   --> $DIR/should_require_well_defined_layout.rs:39:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `should_reject_repr_rust::braces::repr_rust` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `should_reject_repr_rust::braces::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -112,7 +112,7 @@ error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::
   --> $DIR/should_require_well_defined_layout.rs:40:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `should_reject_repr_rust::braces::repr_rust` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `should_reject_repr_rust::braces::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -134,7 +134,7 @@ error[E0277]: `aligned::repr_rust` cannot be safely transmuted into `()`
   --> $DIR/should_require_well_defined_layout.rs:45:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `aligned::repr_rust` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `aligned::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -156,7 +156,7 @@ error[E0277]: `u128` cannot be safely transmuted into `aligned::repr_rust`
   --> $DIR/should_require_well_defined_layout.rs:46:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `aligned::repr_rust` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `aligned::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -178,7 +178,7 @@ error[E0277]: `packed::repr_rust` cannot be safely transmuted into `()`
   --> $DIR/should_require_well_defined_layout.rs:51:52
    |
 LL |         assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                    ^^ `packed::repr_rust` does not have a well-specified layout
+   |                                                    ^^ analyzing the transmutability of `packed::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -200,7 +200,7 @@ error[E0277]: `u128` cannot be safely transmuted into `packed::repr_rust`
   --> $DIR/should_require_well_defined_layout.rs:52:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                               ^^^^^^^^^ `packed::repr_rust` does not have a well-specified layout
+   |                                               ^^^^^^^^^ analyzing the transmutability of `packed::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -222,7 +222,7 @@ error[E0277]: `nested::repr_c` cannot be safely transmuted into `()`
   --> $DIR/should_require_well_defined_layout.rs:58:49
    |
 LL |         assert::is_maybe_transmutable::<repr_c, ()>();
-   |                                                 ^^ `nested::repr_c` does not have a well-specified layout
+   |                                                 ^^ analyzing the transmutability of `nested::repr_c` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -244,7 +244,7 @@ error[E0277]: `u128` cannot be safely transmuted into `nested::repr_c`
   --> $DIR/should_require_well_defined_layout.rs:59:47
    |
 LL |         assert::is_maybe_transmutable::<u128, repr_c>();
-   |                                               ^^^^^^ `nested::repr_c` does not have a well-specified layout
+   |                                               ^^^^^^ analyzing the transmutability of `nested::repr_c` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
diff --git a/tests/ui/transmutability/unions/repr/should_require_well_defined_layout.stderr b/tests/ui/transmutability/unions/repr/should_require_well_defined_layout.stderr
index ee0e8a66434..bec07f13103 100644
--- a/tests/ui/transmutability/unions/repr/should_require_well_defined_layout.stderr
+++ b/tests/ui/transmutability/unions/repr/should_require_well_defined_layout.stderr
@@ -2,7 +2,7 @@ error[E0277]: `should_reject_repr_rust::repr_rust` cannot be safely transmuted i
   --> $DIR/should_require_well_defined_layout.rs:29:48
    |
 LL |     assert::is_maybe_transmutable::<repr_rust, ()>();
-   |                                                ^^ `should_reject_repr_rust::repr_rust` does not have a well-specified layout
+   |                                                ^^ analyzing the transmutability of `should_reject_repr_rust::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14
@@ -24,7 +24,7 @@ error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::
   --> $DIR/should_require_well_defined_layout.rs:30:43
    |
 LL |     assert::is_maybe_transmutable::<u128, repr_rust>();
-   |                                           ^^^^^^^^^ `should_reject_repr_rust::repr_rust` does not have a well-specified layout
+   |                                           ^^^^^^^^^ analyzing the transmutability of `should_reject_repr_rust::repr_rust` is not yet supported.
    |
 note: required by a bound in `is_maybe_transmutable`
   --> $DIR/should_require_well_defined_layout.rs:12:14