diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs index 68e7a29211020..4add0612806b1 100644 --- a/compiler/rustc_feature/src/builtin_attrs.rs +++ b/compiler/rustc_feature/src/builtin_attrs.rs @@ -641,6 +641,11 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[ ErrorFollowing, EncodeCrossCrate::Yes, "rustc_deprecated_safe_2024 is supposed to be used in libstd only", ), + rustc_attr!( + rustc_pub_transparent, Normal, template!(Word), + WarnFollowing, EncodeCrossCrate::Yes, + "used internally to mark types with a `transparent` representation when it is guaranteed by the documentation", + ), // ========================================================================== diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs index 14c5f8d9f16da..728c3790098e7 100644 --- a/compiler/rustc_hir_analysis/src/check/check.rs +++ b/compiler/rustc_hir_analysis/src/check/check.rs @@ -1259,7 +1259,8 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, adt: ty::AdtDef<'tcx>) ty::Tuple(list) => list.iter().try_for_each(|t| check_non_exhaustive(tcx, t)), ty::Array(ty, _) => check_non_exhaustive(tcx, *ty), ty::Adt(def, args) => { - if !def.did().is_local() { + if !def.did().is_local() && !tcx.has_attr(def.did(), sym::rustc_pub_transparent) + { let non_exhaustive = def.is_variant_list_non_exhaustive() || def .variants() diff --git a/compiler/rustc_passes/messages.ftl b/compiler/rustc_passes/messages.ftl index dfc726efeb998..b377c9f52d640 100644 --- a/compiler/rustc_passes/messages.ftl +++ b/compiler/rustc_passes/messages.ftl @@ -657,6 +657,10 @@ passes_rustc_lint_opt_ty = `#[rustc_lint_opt_ty]` should be applied to a struct .label = not a struct +passes_rustc_pub_transparent = + attribute should be applied to `#[repr(transparent)]` types + .label = not a `#[repr(transparent)]` type + passes_rustc_safe_intrinsic = attribute should be applied to intrinsic functions .label = not an intrinsic function diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs index 01cc89a34d5b6..b89b488ba7485 100644 --- a/compiler/rustc_passes/src/check_attr.rs +++ b/compiler/rustc_passes/src/check_attr.rs @@ -250,6 +250,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> { self.check_coroutine(attr, target); } [sym::linkage, ..] => self.check_linkage(attr, span, target), + [sym::rustc_pub_transparent, ..] => self.check_rustc_pub_transparent( attr.span, span, attrs), [ // ok sym::allow @@ -2357,6 +2358,18 @@ impl<'tcx> CheckAttrVisitor<'tcx> { } } } + + fn check_rustc_pub_transparent(&self, attr_span: Span, span: Span, attrs: &[Attribute]) { + if !attrs + .iter() + .filter(|attr| attr.has_name(sym::repr)) + .filter_map(|attr| attr.meta_item_list()) + .flatten() + .any(|nmi| nmi.has_name(sym::transparent)) + { + self.dcx().emit_err(errors::RustcPubTransparent { span, attr_span }); + } + } } impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> { diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs index 1190e60f41f18..f6a57b7d0982d 100644 --- a/compiler/rustc_passes/src/errors.rs +++ b/compiler/rustc_passes/src/errors.rs @@ -622,6 +622,15 @@ pub struct RustcStdInternalSymbol { pub span: Span, } +#[derive(Diagnostic)] +#[diag(passes_rustc_pub_transparent)] +pub struct RustcPubTransparent { + #[primary_span] + pub attr_span: Span, + #[label] + pub span: Span, +} + #[derive(Diagnostic)] #[diag(passes_link_ordinal)] pub struct LinkOrdinal { diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs index 66852e27388fd..58a797b765a03 100644 --- a/compiler/rustc_span/src/symbol.rs +++ b/compiler/rustc_span/src/symbol.rs @@ -1675,6 +1675,7 @@ symbols! { rustc_private, rustc_proc_macro_decls, rustc_promotable, + rustc_pub_transparent, rustc_reallocator, rustc_regions, rustc_reservation_impl, diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs index d860f3415d982..5dd9721d3fee8 100644 --- a/library/core/src/cell.rs +++ b/library/core/src/cell.rs @@ -306,6 +306,7 @@ pub use once::OnceCell; /// See the [module-level documentation](self) for more. #[stable(feature = "rust1", since = "1.0.0")] #[repr(transparent)] +#[cfg_attr(not(bootstrap), rustc_pub_transparent)] pub struct Cell { value: UnsafeCell, } @@ -2055,6 +2056,7 @@ impl fmt::Display for RefMut<'_, T> { #[lang = "unsafe_cell"] #[stable(feature = "rust1", since = "1.0.0")] #[repr(transparent)] +#[cfg_attr(not(bootstrap), rustc_pub_transparent)] pub struct UnsafeCell { value: T, } @@ -2297,6 +2299,7 @@ impl UnsafeCell<*mut T> { /// See [`UnsafeCell`] for details. #[unstable(feature = "sync_unsafe_cell", issue = "95439")] #[repr(transparent)] +#[cfg_attr(not(bootstrap), rustc_pub_transparent)] pub struct SyncUnsafeCell { value: UnsafeCell, } diff --git a/library/core/src/mem/manually_drop.rs b/library/core/src/mem/manually_drop.rs index 00c837041b697..be5cee2e85267 100644 --- a/library/core/src/mem/manually_drop.rs +++ b/library/core/src/mem/manually_drop.rs @@ -47,6 +47,7 @@ use crate::ptr; #[lang = "manually_drop"] #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord, Hash)] #[repr(transparent)] +#[cfg_attr(not(bootstrap), rustc_pub_transparent)] pub struct ManuallyDrop { value: T, } diff --git a/library/core/src/mem/maybe_uninit.rs b/library/core/src/mem/maybe_uninit.rs index f920ab1792daf..c308def2f574a 100644 --- a/library/core/src/mem/maybe_uninit.rs +++ b/library/core/src/mem/maybe_uninit.rs @@ -237,6 +237,7 @@ use crate::{fmt, intrinsics, ptr, slice}; #[lang = "maybe_uninit"] #[derive(Copy)] #[repr(transparent)] +#[cfg_attr(not(bootstrap), rustc_pub_transparent)] pub union MaybeUninit { uninit: (), value: ManuallyDrop, diff --git a/library/core/src/pin.rs b/library/core/src/pin.rs index 0f9e6061c32da..780e476f531f4 100644 --- a/library/core/src/pin.rs +++ b/library/core/src/pin.rs @@ -1084,6 +1084,7 @@ use crate::{cmp, fmt}; #[lang = "pin"] #[fundamental] #[repr(transparent)] +#[cfg_attr(not(bootstrap), rustc_pub_transparent)] #[derive(Copy, Clone)] pub struct Pin { // FIXME(#93176): this field is made `#[unstable] #[doc(hidden)] pub` to: diff --git a/tests/ui/attributes/rustc_pub_transparent.rs b/tests/ui/attributes/rustc_pub_transparent.rs new file mode 100644 index 0000000000000..4508fa39baf8b --- /dev/null +++ b/tests/ui/attributes/rustc_pub_transparent.rs @@ -0,0 +1,25 @@ +#![feature(rustc_attrs, transparent_unions)] + +#[rustc_pub_transparent] +#[repr(transparent)] +union E { + value: T, + uninit: (), +} + +#[repr(transparent)] +#[rustc_pub_transparent] +struct S(T); + +#[rustc_pub_transparent] //~ ERROR attribute should be applied to `#[repr(transparent)]` types +#[repr(C)] +struct S1 { + A: u8, +} + +#[rustc_pub_transparent] //~ ERROR attribute should be applied to `#[repr(transparent)]` types +struct S2 { + value: T, +} + +fn main() {} diff --git a/tests/ui/attributes/rustc_pub_transparent.stderr b/tests/ui/attributes/rustc_pub_transparent.stderr new file mode 100644 index 0000000000000..1d1f9437cb2c1 --- /dev/null +++ b/tests/ui/attributes/rustc_pub_transparent.stderr @@ -0,0 +1,23 @@ +error: attribute should be applied to `#[repr(transparent)]` types + --> $DIR/rustc_pub_transparent.rs:14:1 + | +LL | #[rustc_pub_transparent] + | ^^^^^^^^^^^^^^^^^^^^^^^^ +LL | #[repr(C)] +LL | / struct S1 { +LL | | A: u8, +LL | | } + | |_- not a `#[repr(transparent)]` type + +error: attribute should be applied to `#[repr(transparent)]` types + --> $DIR/rustc_pub_transparent.rs:20:1 + | +LL | #[rustc_pub_transparent] + | ^^^^^^^^^^^^^^^^^^^^^^^^ +LL | / struct S2 { +LL | | value: T, +LL | | } + | |_- not a `#[repr(transparent)]` type + +error: aborting due to 2 previous errors + diff --git a/tests/ui/repr/repr-transparent-non-exhaustive-transparent-in-prose.rs b/tests/ui/repr/repr-transparent-non-exhaustive-transparent-in-prose.rs new file mode 100644 index 0000000000000..6ab34719f0664 --- /dev/null +++ b/tests/ui/repr/repr-transparent-non-exhaustive-transparent-in-prose.rs @@ -0,0 +1,25 @@ +//@ check-pass + +#![feature(sync_unsafe_cell)] +#![allow(unused)] +#![deny(repr_transparent_external_private_fields)] + +// https://github.com/rust-lang/rust/issues/129470 + +struct ZST; + +#[repr(transparent)] +struct TransparentWithManuallyDropZST { + value: i32, + md: std::mem::ManuallyDrop, + mu: std::mem::MaybeUninit, + p: std::pin::Pin, + pd: std::marker::PhantomData, + pp: std::marker::PhantomPinned, + c: std::cell::Cell, + uc: std::cell::UnsafeCell, + suc: std::cell::SyncUnsafeCell, + zst: ZST, +} + +fn main() {}