diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs index 9be28c338f64b..3c5bff3812a94 100644 --- a/compiler/rustc_feature/src/builtin_attrs.rs +++ b/compiler/rustc_feature/src/builtin_attrs.rs @@ -705,7 +705,11 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[ "#[rustc_allow_incoherent_impl] has to be added to all impl items of an incoherent inherent impl." ), rustc_attr!( - rustc_deny_explicit_impl, AttributeType::Normal, template!(Word), ErrorFollowing, @only_local: false, + rustc_deny_explicit_impl, + AttributeType::Normal, + template!(List: "implement_via_object = (true|false)"), + ErrorFollowing, + @only_local: true, "#[rustc_deny_explicit_impl] enforces that a trait can have no user-provided impls" ), rustc_attr!( diff --git a/compiler/rustc_hir_analysis/src/coherence/mod.rs b/compiler/rustc_hir_analysis/src/coherence/mod.rs index 4524b87a418aa..5097f43607e85 100644 --- a/compiler/rustc_hir_analysis/src/coherence/mod.rs +++ b/compiler/rustc_hir_analysis/src/coherence/mod.rs @@ -10,7 +10,6 @@ use rustc_errors::{error_code, struct_span_err}; use rustc_hir::def_id::{DefId, LocalDefId}; use rustc_middle::query::Providers; use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt}; -use rustc_span::sym; use rustc_trait_selection::traits; mod builtin; @@ -44,7 +43,7 @@ fn enforce_trait_manually_implementable( let impl_header_span = tcx.def_span(impl_def_id); // Disallow *all* explicit impls of traits marked `#[rustc_deny_explicit_impl]` - if tcx.has_attr(trait_def_id, sym::rustc_deny_explicit_impl) { + if tcx.trait_def(trait_def_id).deny_explicit_impl { let trait_name = tcx.item_name(trait_def_id); let mut err = struct_span_err!( tcx.sess, diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs index c7b9fc9a697f4..ec378c0984f26 100644 --- a/compiler/rustc_hir_analysis/src/collect.rs +++ b/compiler/rustc_hir_analysis/src/collect.rs @@ -986,6 +986,50 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::TraitDef { no_dups.then_some(list) }); + let mut deny_explicit_impl = false; + let mut implement_via_object = true; + if let Some(attr) = tcx.get_attr(def_id, sym::rustc_deny_explicit_impl) { + deny_explicit_impl = true; + let mut seen_attr = false; + for meta in attr.meta_item_list().iter().flatten() { + if let Some(meta) = meta.meta_item() + && meta.name_or_empty() == sym::implement_via_object + && let Some(lit) = meta.name_value_literal() + { + if seen_attr { + tcx.sess.span_err( + meta.span, + "duplicated `implement_via_object` meta item", + ); + } + seen_attr = true; + + match lit.symbol { + kw::True => { + implement_via_object = true; + } + kw::False => { + implement_via_object = false; + } + _ => { + tcx.sess.span_err( + meta.span, + format!("unknown literal passed to `implement_via_object` attribute: {}", lit.symbol), + ); + } + } + } else { + tcx.sess.span_err( + meta.span(), + format!("unknown meta item passed to `rustc_deny_explicit_impl` {:?}", meta), + ); + } + } + if !seen_attr { + tcx.sess.span_err(attr.span, "missing `implement_via_object` meta item"); + } + } + ty::TraitDef { def_id: def_id.to_def_id(), unsafety, @@ -996,6 +1040,8 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::TraitDef { skip_array_during_method_dispatch, specialization_kind, must_implement_one_of, + implement_via_object, + deny_explicit_impl, } } diff --git a/compiler/rustc_middle/src/ty/trait_def.rs b/compiler/rustc_middle/src/ty/trait_def.rs index e61037e5ea86f..98c70e330f1cc 100644 --- a/compiler/rustc_middle/src/ty/trait_def.rs +++ b/compiler/rustc_middle/src/ty/trait_def.rs @@ -52,6 +52,16 @@ pub struct TraitDef { /// List of functions from `#[rustc_must_implement_one_of]` attribute one of which /// must be implemented. pub must_implement_one_of: Option>, + + /// Whether to add a builtin `dyn Trait: Trait` implementation. + /// This is enabled for all traits except ones marked with + /// `#[rustc_deny_explicit_impl(implement_via_object = false)]`. + pub implement_via_object: bool, + + /// Whether a trait is fully built-in, and any implementation is disallowed. + /// This only applies to built-in traits, and is marked via + /// `#[rustc_deny_explicit_impl(implement_via_object = ...)]`. + pub deny_explicit_impl: bool, } /// Whether this trait is treated specially by the standard library diff --git a/compiler/rustc_passes/messages.ftl b/compiler/rustc_passes/messages.ftl index e76f1614b9334..a607e483c97c7 100644 --- a/compiler/rustc_passes/messages.ftl +++ b/compiler/rustc_passes/messages.ftl @@ -102,9 +102,6 @@ passes_const_impl_const_trait = const `impl`s must be for traits marked with `#[const_trait]` .note = this trait must be annotated with `#[const_trait]` -passes_const_trait = - attribute should be applied to a trait - passes_continue_labeled_block = `continue` pointing to a labeled block .label = labeled blocks cannot be `continue`'d diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs index c35c7da266429..073760f394e8a 100644 --- a/compiler/rustc_passes/src/check_attr.rs +++ b/compiler/rustc_passes/src/check_attr.rs @@ -110,9 +110,6 @@ impl CheckAttrVisitor<'_> { sym::no_coverage => self.check_no_coverage(hir_id, attr, span, target), sym::non_exhaustive => self.check_non_exhaustive(hir_id, attr, span, target), sym::marker => self.check_marker(hir_id, attr, span, target), - sym::rustc_must_implement_one_of => { - self.check_rustc_must_implement_one_of(attr, span, target) - } sym::target_feature => self.check_target_feature(hir_id, attr, span, target), sym::thread_local => self.check_thread_local(attr, span, target), sym::track_caller => { @@ -159,12 +156,14 @@ impl CheckAttrVisitor<'_> { | sym::rustc_dirty | sym::rustc_if_this_changed | sym::rustc_then_this_would_need => self.check_rustc_dirty_clean(&attr), - sym::rustc_coinductive => self.check_rustc_coinductive(&attr, span, target), + sym::rustc_coinductive + | sym::rustc_must_implement_one_of + | sym::rustc_deny_explicit_impl + | sym::const_trait => self.check_must_be_applied_to_trait(&attr, span, target), sym::cmse_nonsecure_entry => { self.check_cmse_nonsecure_entry(hir_id, attr, span, target) } sym::collapse_debuginfo => self.check_collapse_debuginfo(attr, span, target), - sym::const_trait => self.check_const_trait(attr, span, target), sym::must_not_suspend => self.check_must_not_suspend(&attr, span, target), sym::must_use => self.check_must_use(hir_id, &attr, target), sym::rustc_pass_by_value => self.check_pass_by_value(&attr, span, target), @@ -567,25 +566,6 @@ impl CheckAttrVisitor<'_> { } } - /// Checks if the `#[rustc_must_implement_one_of]` attribute on a `target` is valid. Returns `true` if valid. - fn check_rustc_must_implement_one_of( - &self, - attr: &Attribute, - span: Span, - target: Target, - ) -> bool { - match target { - Target::Trait => true, - _ => { - self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait { - attr_span: attr.span, - defn_span: span, - }); - false - } - } - } - /// Checks if the `#[target_feature]` attribute on `item` is valid. Returns `true` if valid. fn check_target_feature( &self, @@ -1591,8 +1571,8 @@ impl CheckAttrVisitor<'_> { } } - /// Checks if the `#[rustc_coinductive]` attribute is applied to a trait. - fn check_rustc_coinductive(&self, attr: &Attribute, span: Span, target: Target) -> bool { + /// Checks if the attribute is applied to a trait. + fn check_must_be_applied_to_trait(&self, attr: &Attribute, span: Span, target: Target) -> bool { match target { Target::Trait => true, _ => { @@ -1986,17 +1966,6 @@ impl CheckAttrVisitor<'_> { } } - /// `#[const_trait]` only applies to traits. - fn check_const_trait(&self, attr: &Attribute, _span: Span, target: Target) -> bool { - match target { - Target::Trait => true, - _ => { - self.tcx.sess.emit_err(errors::ConstTrait { attr_span: attr.span }); - false - } - } - } - fn check_stability_promotable(&self, attr: &Attribute, _span: Span, target: Target) -> bool { match target { Target::Expression => { diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs index ae624dbc9c953..7890c93d5ff0a 100644 --- a/compiler/rustc_passes/src/errors.rs +++ b/compiler/rustc_passes/src/errors.rs @@ -610,13 +610,6 @@ pub struct RustcStdInternalSymbol { pub span: Span, } -#[derive(Diagnostic)] -#[diag(passes_const_trait)] -pub struct ConstTrait { - #[primary_span] - pub attr_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 c5ce2575fff06..cd1a16a1b8966 100644 --- a/compiler/rustc_span/src/symbol.rs +++ b/compiler/rustc_span/src/symbol.rs @@ -817,6 +817,7 @@ symbols! { impl_trait_in_bindings, impl_trait_in_fn_trait_return, impl_trait_projections, + implement_via_object, implied_by, import, import_name_type, diff --git a/compiler/rustc_trait_selection/src/solve/assembly/mod.rs b/compiler/rustc_trait_selection/src/solve/assembly/mod.rs index 1b749b9c854cd..ab8dd854fa4cc 100644 --- a/compiler/rustc_trait_selection/src/solve/assembly/mod.rs +++ b/compiler/rustc_trait_selection/src/solve/assembly/mod.rs @@ -631,6 +631,11 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { goal: Goal<'tcx, G>, candidates: &mut Vec>, ) { + let tcx = self.tcx(); + if !tcx.trait_def(goal.predicate.trait_def_id(tcx)).implement_via_object { + return; + } + let self_ty = goal.predicate.self_ty(); let bounds = match *self_ty.kind() { ty::Bool @@ -663,7 +668,6 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { ty::Dynamic(bounds, ..) => bounds, }; - let tcx = self.tcx(); let own_bounds: FxIndexSet<_> = bounds.iter().map(|bound| bound.with_self_ty(tcx, self_ty)).collect(); for assumption in elaborate(tcx, own_bounds.iter().copied()) diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs index 563cc257e0349..5554c8a0cc4de 100644 --- a/compiler/rustc_trait_selection/src/traits/project.rs +++ b/compiler/rustc_trait_selection/src/traits/project.rs @@ -1586,6 +1586,10 @@ fn assemble_candidates_from_object_ty<'cx, 'tcx>( let tcx = selcx.tcx(); + if !tcx.trait_def(obligation.predicate.trait_def_id(tcx)).implement_via_object { + return; + } + let self_ty = obligation.predicate.self_ty(); let object_ty = selcx.infcx.shallow_resolve(self_ty); let data = match object_ty.kind() { diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs index 3c223db5a0b74..9fb9385eefc9d 100644 --- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs +++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs @@ -554,6 +554,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { "assemble_candidates_from_object_ty", ); + if !self.tcx().trait_def(obligation.predicate.def_id()).implement_via_object { + return; + } + self.infcx.probe(|_snapshot| { if obligation.has_non_region_late_bound() { return; diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs index 9a541ccaeacbc..760e58276fc9f 100644 --- a/library/core/src/marker.rs +++ b/library/core/src/marker.rs @@ -140,7 +140,8 @@ unsafe impl Send for &T {} )] #[fundamental] // for Default, for example, which requires that `[T]: !Default` be evaluatable #[rustc_specialization_trait] -#[rustc_deny_explicit_impl] +#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl(implement_via_object = false))] +#[cfg_attr(bootstrap, rustc_deny_explicit_impl)] #[rustc_coinductive] pub trait Sized { // Empty. @@ -173,7 +174,8 @@ pub trait Sized { /// [nomicon-coerce]: ../../nomicon/coercions.html #[unstable(feature = "unsize", issue = "18598")] #[lang = "unsize"] -#[rustc_deny_explicit_impl] +#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl(implement_via_object = false))] +#[cfg_attr(bootstrap, rustc_deny_explicit_impl)] pub trait Unsize { // Empty. } @@ -854,7 +856,8 @@ impl StructuralEq for PhantomData {} reason = "this trait is unlikely to ever be stabilized, use `mem::discriminant` instead" )] #[lang = "discriminant_kind"] -#[rustc_deny_explicit_impl] +#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl(implement_via_object = false))] +#[cfg_attr(bootstrap, rustc_deny_explicit_impl)] pub trait DiscriminantKind { /// The type of the discriminant, which must satisfy the trait /// bounds required by `mem::Discriminant`. @@ -959,7 +962,8 @@ marker_impls! { #[unstable(feature = "const_trait_impl", issue = "67792")] #[lang = "destruct"] #[rustc_on_unimplemented(message = "can't drop `{Self}`", append_const_msg)] -#[rustc_deny_explicit_impl] +#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl(implement_via_object = false))] +#[cfg_attr(bootstrap, rustc_deny_explicit_impl)] #[const_trait] pub trait Destruct {} @@ -970,7 +974,8 @@ pub trait Destruct {} #[unstable(feature = "tuple_trait", issue = "none")] #[lang = "tuple_trait"] #[rustc_on_unimplemented(message = "`{Self}` is not a tuple")] -#[rustc_deny_explicit_impl] +#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl(implement_via_object = false))] +#[cfg_attr(bootstrap, rustc_deny_explicit_impl)] pub trait Tuple {} /// A marker for pointer-like types. @@ -1025,7 +1030,8 @@ impl ConstParamTy for () {} reason = "internal trait for implementing various traits for all function pointers" )] #[lang = "fn_ptr_trait"] -#[rustc_deny_explicit_impl] +#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl(implement_via_object = false))] +#[cfg_attr(bootstrap, rustc_deny_explicit_impl)] pub trait FnPtr: Copy + Clone { /// Returns the address of the function pointer. #[lang = "fn_ptr_addr"] diff --git a/library/core/src/mem/transmutability.rs b/library/core/src/mem/transmutability.rs index a6f792ed0e3e9..3805d149b704e 100644 --- a/library/core/src/mem/transmutability.rs +++ b/library/core/src/mem/transmutability.rs @@ -7,6 +7,8 @@ use crate::marker::ConstParamTy; /// notwithstanding whatever safety checks you have asked the compiler to [`Assume`] are satisfied. #[unstable(feature = "transmutability", issue = "99571")] #[lang = "transmute_trait"] +#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl(implement_via_object = false))] +#[cfg_attr(bootstrap, rustc_deny_explicit_impl)] pub unsafe trait BikeshedIntrinsicFrom where Src: ?Sized, diff --git a/library/core/src/ptr/metadata.rs b/library/core/src/ptr/metadata.rs index 2ea032d4affe0..daaa44b1d9af5 100644 --- a/library/core/src/ptr/metadata.rs +++ b/library/core/src/ptr/metadata.rs @@ -50,7 +50,8 @@ use crate::hash::{Hash, Hasher}; /// /// [`to_raw_parts`]: *const::to_raw_parts #[lang = "pointee_trait"] -#[rustc_deny_explicit_impl] +#[cfg_attr(not(bootstrap), rustc_deny_explicit_impl(implement_via_object = false))] +#[cfg_attr(bootstrap, rustc_deny_explicit_impl)] pub trait Pointee { /// The type for metadata in pointers and references to `Self`. #[lang = "metadata_type"] diff --git a/tests/ui/rfcs/rfc-2632-const-trait-impl/attr-misuse.stderr b/tests/ui/rfcs/rfc-2632-const-trait-impl/attr-misuse.stderr index b18f33218c2db..998958cedf748 100644 --- a/tests/ui/rfcs/rfc-2632-const-trait-impl/attr-misuse.stderr +++ b/tests/ui/rfcs/rfc-2632-const-trait-impl/attr-misuse.stderr @@ -3,12 +3,16 @@ error: attribute should be applied to a trait | LL | #[const_trait] | ^^^^^^^^^^^^^^ +LL | fn main() {} + | ------------ not a trait error: attribute should be applied to a trait --> $DIR/attr-misuse.rs:5:5 | LL | #[const_trait] | ^^^^^^^^^^^^^^ +LL | fn foo(self); + | ------------- not a trait error: aborting due to 2 previous errors diff --git a/tests/ui/traits/deny-builtin-object-impl.current.stderr b/tests/ui/traits/deny-builtin-object-impl.current.stderr new file mode 100644 index 0000000000000..5c1987426f71f --- /dev/null +++ b/tests/ui/traits/deny-builtin-object-impl.current.stderr @@ -0,0 +1,15 @@ +error[E0277]: the trait bound `dyn NotObject: NotObject` is not satisfied + --> $DIR/deny-builtin-object-impl.rs:18:23 + | +LL | test_not_object::(); + | ^^^^^^^^^^^^^ the trait `NotObject` is not implemented for `dyn NotObject` + | +note: required by a bound in `test_not_object` + --> $DIR/deny-builtin-object-impl.rs:14:23 + | +LL | fn test_not_object() {} + | ^^^^^^^^^ required by this bound in `test_not_object` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/traits/deny-builtin-object-impl.next.stderr b/tests/ui/traits/deny-builtin-object-impl.next.stderr new file mode 100644 index 0000000000000..5c1987426f71f --- /dev/null +++ b/tests/ui/traits/deny-builtin-object-impl.next.stderr @@ -0,0 +1,15 @@ +error[E0277]: the trait bound `dyn NotObject: NotObject` is not satisfied + --> $DIR/deny-builtin-object-impl.rs:18:23 + | +LL | test_not_object::(); + | ^^^^^^^^^^^^^ the trait `NotObject` is not implemented for `dyn NotObject` + | +note: required by a bound in `test_not_object` + --> $DIR/deny-builtin-object-impl.rs:14:23 + | +LL | fn test_not_object() {} + | ^^^^^^^^^ required by this bound in `test_not_object` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/traits/deny-builtin-object-impl.rs b/tests/ui/traits/deny-builtin-object-impl.rs new file mode 100644 index 0000000000000..dce03a43b682a --- /dev/null +++ b/tests/ui/traits/deny-builtin-object-impl.rs @@ -0,0 +1,20 @@ +// revisions: current next +//[next] compile-flags: -Ztrait-solver=next + +#![feature(rustc_attrs)] + +#[rustc_deny_explicit_impl(implement_via_object = true)] +trait YesObject {} + +#[rustc_deny_explicit_impl(implement_via_object = false)] +trait NotObject {} + +fn test_yes_object() {} + +fn test_not_object() {} + +fn main() { + test_yes_object::(); + test_not_object::(); + //~^ ERROR the trait bound `dyn NotObject: NotObject` is not satisfied +} diff --git a/tests/ui/unsized/issue-71659.stderr b/tests/ui/unsized/issue-71659.current.stderr similarity index 89% rename from tests/ui/unsized/issue-71659.stderr rename to tests/ui/unsized/issue-71659.current.stderr index b57b3015e475d..6b982a73952bd 100644 --- a/tests/ui/unsized/issue-71659.stderr +++ b/tests/ui/unsized/issue-71659.current.stderr @@ -1,11 +1,11 @@ error[E0277]: the trait bound `dyn Foo: CastTo<[i32]>` is not satisfied - --> $DIR/issue-71659.rs:30:15 + --> $DIR/issue-71659.rs:33:15 | LL | let x = x.cast::<[i32]>(); | ^^^^ the trait `CastTo<[i32]>` is not implemented for `dyn Foo` | note: required by a bound in `Cast::cast` - --> $DIR/issue-71659.rs:19:15 + --> $DIR/issue-71659.rs:22:15 | LL | fn cast(&self) -> &T | ---- required by a bound in this associated function diff --git a/tests/ui/unsized/issue-71659.next.stderr b/tests/ui/unsized/issue-71659.next.stderr new file mode 100644 index 0000000000000..6b982a73952bd --- /dev/null +++ b/tests/ui/unsized/issue-71659.next.stderr @@ -0,0 +1,18 @@ +error[E0277]: the trait bound `dyn Foo: CastTo<[i32]>` is not satisfied + --> $DIR/issue-71659.rs:33:15 + | +LL | let x = x.cast::<[i32]>(); + | ^^^^ the trait `CastTo<[i32]>` is not implemented for `dyn Foo` + | +note: required by a bound in `Cast::cast` + --> $DIR/issue-71659.rs:22:15 + | +LL | fn cast(&self) -> &T + | ---- required by a bound in this associated function +LL | where +LL | Self: CastTo, + | ^^^^^^^^^ required by this bound in `Cast::cast` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/unsized/issue-71659.rs b/tests/ui/unsized/issue-71659.rs index 3524ca02bbf87..db5c2e205aa13 100644 --- a/tests/ui/unsized/issue-71659.rs +++ b/tests/ui/unsized/issue-71659.rs @@ -1,3 +1,6 @@ +// revisions: current next +//[next] compile-flags: -Ztrait-solver=next + #![feature(unsize)] use std::marker::Unsize;