diff options
4 files changed, 8 insertions, 4 deletions
diff --git a/compiler/rustc_const_eval/src/interpret/call.rs b/compiler/rustc_const_eval/src/interpret/call.rs index 0f2b22f035b..97f7242b336 100644 --- a/compiler/rustc_const_eval/src/interpret/call.rs +++ b/compiler/rustc_const_eval/src/interpret/call.rs @@ -234,6 +234,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { // so we implement a type-based check that reflects the guaranteed rules for ABI compatibility. if self.layout_compat(caller_abi.layout, callee_abi.layout)? { // Ensure that our checks imply actual ABI compatibility for this concrete call. + // (This can fail e.g. if `#[rustc_nonnull_optimization_guaranteed]` is used incorrectly.) assert!(caller_abi.eq_abi(callee_abi)); Ok(true) } else { diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs index fa5f152132a..efb582fde1b 100644 --- a/compiler/rustc_feature/src/builtin_attrs.rs +++ b/compiler/rustc_feature/src/builtin_attrs.rs @@ -859,8 +859,10 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[ rustc_attr!( rustc_nonnull_optimization_guaranteed, Normal, template!(Word), WarnFollowing, EncodeCrossCrate::Yes, - "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable \ - niche optimizations in libcore and libstd and will never be stable", + "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to document \ + guaranteed niche optimizations in libcore and libstd and will never be stable\n\ + (note that the compiler does not even check whether the type indeed is being non-null-optimized; \ + it is your responsibility to ensure that the attribute is only used on types that are optimized)", ), // ========================================================================== diff --git a/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs index 667bc9f8ddf..7ae4a8d911b 100644 --- a/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs +++ b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.rs @@ -2,6 +2,6 @@ #[rustc_variance] //~ ERROR the `#[rustc_variance]` attribute is just used for rustc unit tests and will never be stable #[rustc_error] //~ ERROR the `#[rustc_error]` attribute is just used for rustc unit tests and will never be stable -#[rustc_nonnull_optimization_guaranteed] //~ ERROR the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable niche optimizations in libcore and libstd and will never be stable +#[rustc_nonnull_optimization_guaranteed] //~ ERROR the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to document guaranteed niche optimizations in libcore and libstd and will never be stable fn main() {} diff --git a/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr index 8177d5ef6be..8c3a8eb2df8 100644 --- a/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr +++ b/tests/ui/feature-gates/feature-gate-rustc-attrs-1.stderr @@ -16,7 +16,8 @@ LL | #[rustc_error] = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date -error[E0658]: the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable niche optimizations in libcore and libstd and will never be stable +error[E0658]: the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to document guaranteed niche optimizations in libcore and libstd and will never be stable + (note that the compiler does not even check whether the type indeed is being non-null-optimized; it is your responsibility to ensure that the attribute is only used on types that are optimized) --> $DIR/feature-gate-rustc-attrs-1.rs:5:1 | LL | #[rustc_nonnull_optimization_guaranteed] |