diff --git a/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl b/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl index 357c6900a70e5..7ac44312695d9 100644 --- a/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl +++ b/compiler/rustc_error_messages/locales/en-US/hir_analysis.ftl @@ -137,3 +137,12 @@ hir_analysis_expected_used_symbol = expected `used`, `used(compiler)` or `used(l hir_analysis_missing_parentheses_in_range = can't call method `{$method_name}` on type `{$ty_str}` hir_analysis_add_missing_parentheses_in_range = you must surround the range in parentheses to call its `{$func_name}` function + +hir_analysis_const_impl_for_non_const_trait = + const `impl` for trait `{$trait_name}` which is not marked with `#[const_trait]` + .suggestion = mark `{$trait_name}` as const + .note = marking a trait with `#[const_trait]` ensures all default method bodies are `const` + .adding = adding a non-const method body in the future would be a breaking change + +hir_analysis_const_bound_for_non_const_trait = + ~const can only be applied to `#[const_trait]` traits diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs index a0350c26d827c..6baf98449775d 100644 --- a/compiler/rustc_hir_analysis/src/astconv/mod.rs +++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs @@ -36,7 +36,7 @@ use rustc_session::lint::builtin::{AMBIGUOUS_ASSOCIATED_ITEMS, BARE_TRAIT_OBJECT use rustc_span::edition::Edition; use rustc_span::lev_distance::find_best_match_for_name; use rustc_span::symbol::{kw, Ident, Symbol}; -use rustc_span::Span; +use rustc_span::{sym, Span}; use rustc_target::spec::abi; use rustc_trait_selection::traits; use rustc_trait_selection::traits::astconv_object_safety_violations; @@ -275,6 +275,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { item_segment.args(), item_segment.infer_args, None, + None, ); if let Some(b) = item_segment.args().bindings.first() { Self::prohibit_assoc_ty_binding(self.tcx(), b.span); @@ -324,6 +325,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { generic_args: &'a hir::GenericArgs<'_>, infer_args: bool, self_ty: Option>, + constness: Option, ) -> (SubstsRef<'tcx>, GenericArgCountResult) { // If the type is parameterized by this region, then replace this // region with the current anon region binding (in other words, @@ -534,6 +536,12 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { &mut substs_ctx, ); + if let Some(ty::BoundConstness::ConstIfConst) = constness + && generics.has_self && !tcx.has_attr(def_id, sym::const_trait) + { + tcx.sess.emit_err(crate::errors::ConstBoundForNonConstTrait { span } ); + } + (substs, arg_count) } @@ -601,6 +609,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { item_segment.args(), item_segment.infer_args, None, + None, ); if let Some(b) = item_segment.args().bindings.first() { @@ -620,6 +629,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { &self, trait_ref: &hir::TraitRef<'_>, self_ty: Ty<'tcx>, + constness: ty::BoundConstness, ) -> ty::TraitRef<'tcx> { self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1.iter(), |_| {}); @@ -629,6 +639,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { self_ty, trait_ref.path.segments.last().unwrap(), true, + Some(constness), ) } @@ -655,6 +666,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { args, infer_args, Some(self_ty), + Some(constness), ); let tcx = self.tcx(); @@ -680,6 +692,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { speculative, &mut dup_bindings, binding_span.unwrap_or(binding.span), + constness, ); // Okay to ignore `Err` because of `ErrorGuaranteed` (see above). } @@ -783,6 +796,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { self_ty: Ty<'tcx>, trait_segment: &hir::PathSegment<'_>, is_impl: bool, + constness: Option, ) -> ty::TraitRef<'tcx> { let (substs, _) = self.create_substs_for_ast_trait_ref( span, @@ -790,6 +804,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { self_ty, trait_segment, is_impl, + constness, ); if let Some(b) = trait_segment.args().bindings.first() { Self::prohibit_assoc_ty_binding(self.tcx(), b.span); @@ -805,6 +820,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { self_ty: Ty<'tcx>, trait_segment: &'a hir::PathSegment<'a>, is_impl: bool, + constness: Option, ) -> (SubstsRef<'tcx>, GenericArgCountResult) { self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment, is_impl); @@ -816,6 +832,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { trait_segment.args(), trait_segment.infer_args, Some(self_ty), + constness, ) } @@ -1027,6 +1044,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { speculative: bool, dup_bindings: &mut FxHashMap, path_span: Span, + constness: ty::BoundConstness, ) -> Result<(), ErrorGuaranteed> { // Given something like `U: SomeTrait`, we want to produce a // predicate like `::T = X`. This is somewhat @@ -1122,10 +1140,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { trait_ref.substs, ); - debug!( - "add_predicates_for_ast_type_binding: substs for trait-ref and assoc_item: {:?}", - substs_trait_ref_and_assoc_item - ); + debug!(?substs_trait_ref_and_assoc_item); ty::ProjectionTy { item_def_id: assoc_item.def_id, @@ -1146,8 +1161,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { tcx.collect_constrained_late_bound_regions(&projection_ty); let late_bound_in_ty = tcx.collect_referenced_late_bound_regions(&trait_ref.rebind(ty)); - debug!("late_bound_in_trait_ref = {:?}", late_bound_in_trait_ref); - debug!("late_bound_in_ty = {:?}", late_bound_in_ty); + debug!(?late_bound_in_trait_ref); + debug!(?late_bound_in_ty); // FIXME: point at the type params that don't have appropriate lifetimes: // struct S1 Fn(&i32, &i32) -> &'a i32>(F); @@ -1648,6 +1663,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { // Checks that `bounds` contains exactly one element and reports appropriate // errors otherwise. + #[instrument(level = "debug", skip(self, all_candidates, ty_param_name, is_equality), ret)] fn one_bound_for_assoc_type( &self, all_candidates: impl Fn() -> I, @@ -1677,10 +1693,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { return Err(reported); } }; - debug!("one_bound_for_assoc_type: bound = {:?}", bound); + debug!(?bound); if let Some(bound2) = next_cand { - debug!("one_bound_for_assoc_type: bound2 = {:?}", bound2); + debug!(?bound2); let is_equality = is_equality(); let bounds = IntoIterator::into_iter([bound, bound2]).chain(matching_candidates); @@ -1776,6 +1792,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { // parameter or `Self`. // NOTE: When this function starts resolving `Trait::AssocTy` successfully // it should also start reporting the `BARE_TRAIT_OBJECTS` lint. + #[instrument(level = "debug", skip(self, hir_ref_id, span, qself, assoc_segment), fields(assoc_ident=?assoc_segment.ident), ret)] pub fn associated_path_to_ty( &self, hir_ref_id: hir::HirId, @@ -1793,8 +1810,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { Res::Err }; - debug!("associated_path_to_ty: {:?}::{}", qself_ty, assoc_ident); - // Check if we have an enum variant. let mut variant_resolution = None; if let ty::Adt(adt_def, _) = qself_ty.kind() { @@ -2050,6 +2065,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { item_def_id: DefId, trait_segment: &hir::PathSegment<'_>, item_segment: &hir::PathSegment<'_>, + constness: ty::BoundConstness, ) -> Ty<'tcx> { let tcx = self.tcx(); @@ -2094,8 +2110,14 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { debug!("qpath_to_ty: self_type={:?}", self_ty); - let trait_ref = - self.ast_path_to_mono_trait_ref(span, trait_def_id, self_ty, trait_segment, false); + let trait_ref = self.ast_path_to_mono_trait_ref( + span, + trait_def_id, + self_ty, + trait_segment, + false, + Some(constness), + ); let item_substs = self.create_substs_for_associated_item( span, @@ -2534,12 +2556,19 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { Res::Def(DefKind::AssocTy, def_id) => { debug_assert!(path.segments.len() >= 2); self.prohibit_generics(path.segments[..path.segments.len() - 2].iter(), |_| {}); + // HACK: until we support ``, assume all of them are. + let constness = if tcx.has_attr(tcx.parent(def_id), sym::const_trait) { + ty::BoundConstness::ConstIfConst + } else { + ty::BoundConstness::NotConst + }; self.qpath_to_ty( span, opt_self_ty, def_id, &path.segments[path.segments.len() - 2], path.segments.last().unwrap(), + constness, ) } Res::PrimTy(prim_ty) => { @@ -2658,6 +2687,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { &GenericArgs::none(), true, None, + None, ); EarlyBinder(self.normalize_ty(span, tcx.at(span).type_of(def_id))) .subst(tcx, substs) @@ -2766,6 +2796,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { } } + #[instrument(level = "debug", skip(self, hir_id, unsafety, abi, decl, generics, hir_ty), ret)] pub fn ty_of_fn( &self, hir_id: hir::HirId, @@ -2775,8 +2806,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { generics: Option<&hir::Generics<'_>>, hir_ty: Option<&hir::Ty<'_>>, ) -> ty::PolyFnSig<'tcx> { - debug!("ty_of_fn"); - let tcx = self.tcx(); let bound_vars = tcx.late_bound_vars(hir_id); debug!(?bound_vars); @@ -2826,7 +2855,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { hir::FnRetTy::DefaultReturn(..) => tcx.mk_unit(), }; - debug!("ty_of_fn: output_ty={:?}", output_ty); + debug!(?output_ty); let fn_ty = tcx.mk_fn_sig(input_tys.into_iter(), output_ty, decl.c_variadic, unsafety, abi); let bare_fn_ty = ty::Binder::bind_with_vars(fn_ty, bound_vars); @@ -2903,8 +2932,11 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { let hir::Node::Item(hir::Item { kind: hir::ItemKind::Impl(i), .. }) = hir.get(hir.get_parent_node(fn_hir_id)) else { bug!("ImplItem should have Impl parent") }; - let trait_ref = - self.instantiate_mono_trait_ref(i.of_trait.as_ref()?, self.ast_ty_to_ty(i.self_ty)); + let trait_ref = self.instantiate_mono_trait_ref( + i.of_trait.as_ref()?, + self.ast_ty_to_ty(i.self_ty), + ty::BoundConstness::NotConst, + ); let assoc = tcx.associated_items(trait_ref.def_id).find_by_name_and_kind( tcx, diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs index 66ca7d7aa08f9..e261bb07f9545 100644 --- a/compiler/rustc_hir_analysis/src/collect.rs +++ b/compiler/rustc_hir_analysis/src/collect.rs @@ -1143,7 +1143,7 @@ fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> { } ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => { - // Do not try to inference the return type for a impl method coming from a trait + // Do not try to infer the return type for a impl method coming from a trait if let Item(hir::Item { kind: ItemKind::Impl(i), .. }) = tcx.hir().get(tcx.hir().get_parent_node(hir_id)) && i.of_trait.is_some() @@ -1286,15 +1286,46 @@ fn infer_return_ty_for_fn_sig<'tcx>( fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option> { let icx = ItemCtxt::new(tcx, def_id); - match tcx.hir().expect_item(def_id.expect_local()).kind { + let item = tcx.hir().expect_item(def_id.expect_local()); + match item.kind { hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| { let selfty = tcx.type_of(def_id); - >::instantiate_mono_trait_ref(&icx, ast_trait_ref, selfty) + >::instantiate_mono_trait_ref( + &icx, + ast_trait_ref, + selfty, + check_impl_constness(tcx, impl_.constness, ast_trait_ref), + ) }), _ => bug!(), } } +fn check_impl_constness( + tcx: TyCtxt<'_>, + constness: hir::Constness, + ast_trait_ref: &hir::TraitRef<'_>, +) -> ty::BoundConstness { + match constness { + hir::Constness::Const => { + if let Some(trait_def_id) = ast_trait_ref.trait_def_id() && !tcx.has_attr(trait_def_id, sym::const_trait) { + let trait_name = tcx.item_name(trait_def_id).to_string(); + tcx.sess.emit_err(errors::ConstImplForNonConstTrait { + trait_ref_span: ast_trait_ref.path.span, + trait_name, + local_trait_span: trait_def_id.as_local().map(|_| tcx.def_span(trait_def_id).shrink_to_lo()), + marking: (), + adding: (), + }); + ty::BoundConstness::NotConst + } else { + ty::BoundConstness::ConstIfConst + } + }, + hir::Constness::NotConst => ty::BoundConstness::NotConst, + } +} + fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity { let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl); let item = tcx.hir().expect_item(def_id.expect_local()); diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs index 9457da32ce65a..bd0c1f5dd1098 100644 --- a/compiler/rustc_hir_analysis/src/errors.rs +++ b/compiler/rustc_hir_analysis/src/errors.rs @@ -249,3 +249,24 @@ pub struct ExpectedUsedSymbol { #[primary_span] pub span: Span, } + +#[derive(Diagnostic)] +#[diag(hir_analysis_const_impl_for_non_const_trait)] +pub struct ConstImplForNonConstTrait { + #[primary_span] + pub trait_ref_span: Span, + pub trait_name: String, + #[suggestion(applicability = "machine-applicable", code = "#[const_trait]")] + pub local_trait_span: Option, + #[note] + pub marking: (), + #[note(adding)] + pub adding: (), +} + +#[derive(Diagnostic)] +#[diag(hir_analysis_const_bound_for_non_const_trait)] +pub struct ConstBoundForNonConstTrait { + #[primary_span] + pub span: Span, +} diff --git a/compiler/rustc_trait_selection/src/traits/wf.rs b/compiler/rustc_trait_selection/src/traits/wf.rs index 0870833cc35ae..30feabe1a0959 100644 --- a/compiler/rustc_trait_selection/src/traits/wf.rs +++ b/compiler/rustc_trait_selection/src/traits/wf.rs @@ -303,32 +303,6 @@ impl<'tcx> WfPredicates<'tcx> { let obligations = if trait_pred.constness == ty::BoundConstness::NotConst { self.nominal_obligations_without_const(trait_ref.def_id, trait_ref.substs) } else { - if !tcx.has_attr(trait_ref.def_id, rustc_span::sym::const_trait) { - if let Some(item) = self.item && - let hir::ItemKind::Impl(impl_) = item.kind && - let Some(trait_) = &impl_.of_trait && - let Some(def_id) = trait_.trait_def_id() && - def_id == trait_ref.def_id - { - let trait_name = tcx.item_name(def_id); - let mut err = tcx.sess.struct_span_err( - self.span, - &format!("const `impl` for trait `{trait_name}` which is not marked with `#[const_trait]`"), - ); - if def_id.is_local() { - let sp = tcx.def_span(def_id).shrink_to_lo(); - err.span_suggestion(sp, &format!("mark `{trait_name}` as const"), "#[const_trait]", rustc_errors::Applicability::MachineApplicable); - } - err.note("marking a trait with `#[const_trait]` ensures all default method bodies are `const`"); - err.note("adding a non-const method body in the future would be a breaking change"); - err.emit(); - } else { - tcx.sess.span_err( - self.span, - "~const can only be applied to `#[const_trait]` traits", - ); - } - } self.nominal_obligations(trait_ref.def_id, trait_ref.substs) }; diff --git a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.nn.stderr b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.nn.stderr index b86acb2cc9ab2..d4f42b787e4da 100644 --- a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.nn.stderr +++ b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.nn.stderr @@ -1,8 +1,8 @@ error: ~const can only be applied to `#[const_trait]` traits - --> $DIR/super-traits-fail-2.rs:11:12 + --> $DIR/super-traits-fail-2.rs:11:19 | LL | trait Bar: ~const Foo {} - | ^^^^^^^^^^ + | ^^^ error: aborting due to previous error diff --git a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.ny.stderr b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.ny.stderr index b86acb2cc9ab2..d4f42b787e4da 100644 --- a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.ny.stderr +++ b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-2.ny.stderr @@ -1,8 +1,8 @@ error: ~const can only be applied to `#[const_trait]` traits - --> $DIR/super-traits-fail-2.rs:11:12 + --> $DIR/super-traits-fail-2.rs:11:19 | LL | trait Bar: ~const Foo {} - | ^^^^^^^^^^ + | ^^^ error: aborting due to previous error diff --git a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.nn.stderr b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.nn.stderr index 191edca1761c8..d433e1cfa698a 100644 --- a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.nn.stderr +++ b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.nn.stderr @@ -1,14 +1,14 @@ error: ~const can only be applied to `#[const_trait]` traits - --> $DIR/super-traits-fail-3.rs:12:12 + --> $DIR/super-traits-fail-3.rs:12:19 | LL | trait Bar: ~const Foo {} - | ^^^^^^^^^^ + | ^^^ error: ~const can only be applied to `#[const_trait]` traits - --> $DIR/super-traits-fail-3.rs:15:17 + --> $DIR/super-traits-fail-3.rs:15:24 | LL | const fn foo(x: &T) { - | ^^^^^^^^^^ + | ^^^ error: aborting due to 2 previous errors diff --git a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.ny.stderr b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.ny.stderr index a3b4c302a57f8..2a7e8e00bc78c 100644 --- a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.ny.stderr +++ b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.ny.stderr @@ -1,8 +1,8 @@ error: ~const can only be applied to `#[const_trait]` traits - --> $DIR/super-traits-fail-3.rs:12:12 + --> $DIR/super-traits-fail-3.rs:12:19 | LL | trait Bar: ~const Foo {} - | ^^^^^^^^^^ + | ^^^ error: aborting due to previous error diff --git a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.yn.stderr b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.yn.stderr index 9d61166546593..e5978c12a0981 100644 --- a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.yn.stderr +++ b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail-3.yn.stderr @@ -1,8 +1,8 @@ error: ~const can only be applied to `#[const_trait]` traits - --> $DIR/super-traits-fail-3.rs:15:17 + --> $DIR/super-traits-fail-3.rs:15:24 | LL | const fn foo(x: &T) { - | ^^^^^^^^^^ + | ^^^ error: aborting due to previous error