diff options
Diffstat (limited to 'compiler/rustc_ast_lowering/src/item.rs')
| -rw-r--r-- | compiler/rustc_ast_lowering/src/item.rs | 112 |
1 files changed, 38 insertions, 74 deletions
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs index abd70c7517c..ddf01b69e7f 100644 --- a/compiler/rustc_ast_lowering/src/item.rs +++ b/compiler/rustc_ast_lowering/src/item.rs @@ -16,14 +16,11 @@ use smallvec::{SmallVec, smallvec}; use thin_vec::ThinVec; use tracing::instrument; -use super::errors::{ - InvalidAbi, InvalidAbiSuggestion, MisplacedRelaxTraitBound, TupleStructWithDefault, - UnionWithDefault, -}; +use super::errors::{InvalidAbi, InvalidAbiSuggestion, TupleStructWithDefault, UnionWithDefault}; use super::stability::{enabled_names, gate_unstable_abi}; use super::{ AstOwner, FnDeclKind, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode, - ResolverAstLoweringExt, + RelaxedBoundForbiddenReason, RelaxedBoundPolicy, ResolverAstLoweringExt, }; pub(super) struct ItemLowerer<'a, 'hir> { @@ -435,6 +432,7 @@ impl<'hir> LoweringContext<'_, 'hir> { |this| { let bounds = this.lower_param_bounds( bounds, + RelaxedBoundPolicy::Forbidden(RelaxedBoundForbiddenReason::SuperTrait), ImplTraitContext::Disallowed(ImplTraitPosition::Bound), ); let items = this.arena.alloc_from_iter( @@ -455,6 +453,7 @@ impl<'hir> LoweringContext<'_, 'hir> { |this| { this.lower_param_bounds( bounds, + RelaxedBoundPolicy::Allowed, ImplTraitContext::Disallowed(ImplTraitPosition::Bound), ) }, @@ -940,6 +939,7 @@ impl<'hir> LoweringContext<'_, 'hir> { hir::TraitItemKind::Type( this.lower_param_bounds( bounds, + RelaxedBoundPolicy::Allowed, ImplTraitContext::Disallowed(ImplTraitPosition::Generic), ), ty, @@ -1677,61 +1677,6 @@ impl<'hir> LoweringContext<'_, 'hir> { assert!(self.impl_trait_defs.is_empty()); assert!(self.impl_trait_bounds.is_empty()); - // Error if `?Trait` bounds in where clauses don't refer directly to type parameters. - // Note: we used to clone these bounds directly onto the type parameter (and avoid lowering - // these into hir when we lower thee where clauses), but this makes it quite difficult to - // keep track of the Span info. Now, `<dyn HirTyLowerer>::add_implicit_sized_bound` - // checks both param bounds and where clauses for `?Sized`. - for pred in &generics.where_clause.predicates { - let WherePredicateKind::BoundPredicate(bound_pred) = &pred.kind else { - continue; - }; - let compute_is_param = || { - // Check if the where clause type is a plain type parameter. - match self - .resolver - .get_partial_res(bound_pred.bounded_ty.id) - .and_then(|r| r.full_res()) - { - Some(Res::Def(DefKind::TyParam, def_id)) - if bound_pred.bound_generic_params.is_empty() => - { - generics - .params - .iter() - .any(|p| def_id == self.local_def_id(p.id).to_def_id()) - } - // Either the `bounded_ty` is not a plain type parameter, or - // it's not found in the generic type parameters list. - _ => false, - } - }; - // We only need to compute this once per `WherePredicate`, but don't - // need to compute this at all unless there is a Maybe bound. - let mut is_param: Option<bool> = None; - for bound in &bound_pred.bounds { - if !matches!( - *bound, - GenericBound::Trait(PolyTraitRef { - modifiers: TraitBoundModifiers { polarity: BoundPolarity::Maybe(_), .. }, - .. - }) - ) { - continue; - } - let is_param = *is_param.get_or_insert_with(compute_is_param); - if !is_param && !self.tcx.features().more_maybe_bounds() { - self.tcx - .sess - .create_feature_err( - MisplacedRelaxTraitBound { span: bound.span() }, - sym::more_maybe_bounds, - ) - .emit(); - } - } - } - let mut predicates: SmallVec<[hir::WherePredicate<'hir>; 4]> = SmallVec::new(); predicates.extend(generics.params.iter().filter_map(|param| { self.lower_generic_bound_predicate( @@ -1741,6 +1686,7 @@ impl<'hir> LoweringContext<'_, 'hir> { ¶m.bounds, param.colon_span, generics.span, + RelaxedBoundPolicy::Allowed, itctx, PredicateOrigin::GenericParam, ) @@ -1750,7 +1696,7 @@ impl<'hir> LoweringContext<'_, 'hir> { .where_clause .predicates .iter() - .map(|predicate| self.lower_where_predicate(predicate)), + .map(|predicate| self.lower_where_predicate(predicate, &generics.params)), ); let mut params: SmallVec<[hir::GenericParam<'hir>; 4]> = self @@ -1827,6 +1773,7 @@ impl<'hir> LoweringContext<'_, 'hir> { bounds: &[GenericBound], colon_span: Option<Span>, parent_span: Span, + rbp: RelaxedBoundPolicy<'_>, itctx: ImplTraitContext, origin: PredicateOrigin, ) -> Option<hir::WherePredicate<'hir>> { @@ -1835,7 +1782,7 @@ impl<'hir> LoweringContext<'_, 'hir> { return None; } - let bounds = self.lower_param_bounds(bounds, itctx); + let bounds = self.lower_param_bounds(bounds, rbp, itctx); let param_span = ident.span; @@ -1887,7 +1834,11 @@ impl<'hir> LoweringContext<'_, 'hir> { Some(hir::WherePredicate { hir_id, span, kind }) } - fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate<'hir> { + fn lower_where_predicate( + &mut self, + pred: &WherePredicate, + params: &[ast::GenericParam], + ) -> hir::WherePredicate<'hir> { let hir_id = self.lower_node_id(pred.id); let span = self.lower_span(pred.span); self.lower_attrs(hir_id, &pred.attrs, span); @@ -1896,17 +1847,29 @@ impl<'hir> LoweringContext<'_, 'hir> { bound_generic_params, bounded_ty, bounds, - }) => hir::WherePredicateKind::BoundPredicate(hir::WhereBoundPredicate { - bound_generic_params: self - .lower_generic_params(bound_generic_params, hir::GenericParamSource::Binder), - bounded_ty: self - .lower_ty(bounded_ty, ImplTraitContext::Disallowed(ImplTraitPosition::Bound)), - bounds: self.lower_param_bounds( - bounds, - ImplTraitContext::Disallowed(ImplTraitPosition::Bound), - ), - origin: PredicateOrigin::WhereClause, - }), + }) => { + let rbp = if bound_generic_params.is_empty() { + RelaxedBoundPolicy::AllowedIfOnTyParam(bounded_ty.id, params) + } else { + RelaxedBoundPolicy::Forbidden(RelaxedBoundForbiddenReason::LateBoundVarsInScope) + }; + hir::WherePredicateKind::BoundPredicate(hir::WhereBoundPredicate { + bound_generic_params: self.lower_generic_params( + bound_generic_params, + hir::GenericParamSource::Binder, + ), + bounded_ty: self.lower_ty( + bounded_ty, + ImplTraitContext::Disallowed(ImplTraitPosition::Bound), + ), + bounds: self.lower_param_bounds( + bounds, + rbp, + ImplTraitContext::Disallowed(ImplTraitPosition::Bound), + ), + origin: PredicateOrigin::WhereClause, + }) + } WherePredicateKind::RegionPredicate(WhereRegionPredicate { lifetime, bounds }) => { hir::WherePredicateKind::RegionPredicate(hir::WhereRegionPredicate { lifetime: self.lower_lifetime( @@ -1916,6 +1879,7 @@ impl<'hir> LoweringContext<'_, 'hir> { ), bounds: self.lower_param_bounds( bounds, + RelaxedBoundPolicy::Allowed, ImplTraitContext::Disallowed(ImplTraitPosition::Bound), ), in_where_clause: true, |