Rollup merge of rust-lang#128727 - RalfJung:conflicting-repr-future-incompat, r=lcnr

bump conflicting_repr_hints lint to be shown in dependencies

This has been a future compatibility lint for years, let's bump it up to be shown in dependencies (so that hopefully we can then make it a hard error fairly soon).

Cc rust-lang#68585

Author: matthiaskrgr

compiler/rustc_lint_defs/src/builtin.rs

@@ -251,7 +251,7 @@ declare_lint! {
     Deny,
     "conflicts between `#[repr(..)]` hints that were previously accepted and used in practice",
     @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseErrorDontReportInDeps,
+        reason: FutureIncompatibilityReason::FutureReleaseErrorReportInDeps,
         reference: "issue #68585 <https://github.com/rust-lang/rust/issues/68585>",
     };
 }

tests/ui/feature-gates/feature-gate-repr-simd.stderr

@@ -35,3 +35,17 @@ error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0566, E0658.
 For more information about an error, try `rustc --explain E0566`.
+Future incompatibility report: Future breakage diagnostic:
+error[E0566]: conflicting representation hints
+  --> $DIR/feature-gate-repr-simd.rs:4:8
+   |
+LL | #[repr(C)]
+   |        ^
+LL |
+LL | #[repr(simd)]
+   |        ^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #68585 <https://github.com/rust-lang/rust/issues/68585>
+   = note: `#[deny(conflicting_repr_hints)]` on by default
+

tests/ui/issues/issue-47094.stderr

@@ -23,3 +23,28 @@ LL | #[repr(u8)]
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0566`.
+Future incompatibility report: Future breakage diagnostic:
+error[E0566]: conflicting representation hints
+  --> $DIR/issue-47094.rs:1:8
+   |
+LL | #[repr(C, u8)]
+   |        ^  ^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #68585 <https://github.com/rust-lang/rust/issues/68585>
+   = note: `#[deny(conflicting_repr_hints)]` on by default
+
+Future breakage diagnostic:
+error[E0566]: conflicting representation hints
+  --> $DIR/issue-47094.rs:8:8
+   |
+LL | #[repr(C)]
+   |        ^
+LL |
+LL | #[repr(u8)]
+   |        ^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #68585 <https://github.com/rust-lang/rust/issues/68585>
+   = note: `#[deny(conflicting_repr_hints)]` on by default
+

tests/ui/repr/conflicting-repr-hints.stderr

@@ -81,3 +81,25 @@ error: aborting due to 12 previous errors
 
 Some errors have detailed explanations: E0566, E0587, E0634.
 For more information about an error, try `rustc --explain E0566`.
+Future incompatibility report: Future breakage diagnostic:
+error[E0566]: conflicting representation hints
+  --> $DIR/conflicting-repr-hints.rs:13:8
+   |
+LL | #[repr(C, u64)]
+   |        ^  ^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #68585 <https://github.com/rust-lang/rust/issues/68585>
+   = note: `#[deny(conflicting_repr_hints)]` on by default
+
+Future breakage diagnostic:
+error[E0566]: conflicting representation hints
+  --> $DIR/conflicting-repr-hints.rs:19:8
+   |
+LL | #[repr(u32, u64)]
+   |        ^^^  ^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #68585 <https://github.com/rust-lang/rust/issues/68585>
+   = note: `#[deny(conflicting_repr_hints)]` on by default
+