diff options
Diffstat (limited to 'compiler/rustc_ast_lowering/src/lib.rs')
| -rw-r--r-- | compiler/rustc_ast_lowering/src/lib.rs | 67 |
1 files changed, 44 insertions, 23 deletions
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs index b5b28bf8e31..cd6614a54a4 100644 --- a/compiler/rustc_ast_lowering/src/lib.rs +++ b/compiler/rustc_ast_lowering/src/lib.rs @@ -247,7 +247,7 @@ enum ImplTraitContext { in_trait: bool, }, /// Impl trait in type aliases. - TypeAliasesOpaqueTy, + TypeAliasesOpaqueTy { in_assoc_ty: bool }, /// `impl Trait` is unstably accepted in this position. FeatureGated(ImplTraitPosition, Symbol), /// `impl Trait` is not accepted in this position. @@ -1190,13 +1190,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { // parsing. We try to resolve that ambiguity by attempting resolution in both the // type and value namespaces. If we resolved the path in the value namespace, we // transform it into a generic const argument. - TyKind::Path(qself, path) => { + TyKind::Path(None, path) => { if let Some(res) = self .resolver .get_partial_res(ty.id) .and_then(|partial_res| partial_res.full_res()) { - if !res.matches_ns(Namespace::TypeNS) { + if !res.matches_ns(Namespace::TypeNS) + && path.is_potential_trivial_const_arg() + { debug!( "lower_generic_arg: Lowering type argument as const argument: {:?}", ty, @@ -1218,7 +1220,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { let path_expr = Expr { id: ty.id, - kind: ExprKind::Path(qself.clone(), path.clone()), + kind: ExprKind::Path(None, path.clone()), span, attrs: AttrVec::new(), tokens: None, @@ -1368,13 +1370,17 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { this.arena.alloc_from_iter(bounds.iter().filter_map(|bound| match bound { GenericBound::Trait( ty, - TraitBoundModifier::None | TraitBoundModifier::MaybeConst, + TraitBoundModifier::None + | TraitBoundModifier::MaybeConst + | TraitBoundModifier::Negative, ) => Some(this.lower_poly_trait_ref(ty, itctx)), // `~const ?Bound` will cause an error during AST validation // anyways, so treat it like `?Bound` as compilation proceeds. GenericBound::Trait( _, - TraitBoundModifier::Maybe | TraitBoundModifier::MaybeConstMaybe, + TraitBoundModifier::Maybe + | TraitBoundModifier::MaybeConstMaybe + | TraitBoundModifier::MaybeConstNegative, ) => None, GenericBound::Outlives(lifetime) => { if lifetime_bound.is_none() { @@ -1401,14 +1407,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { *in_trait, itctx, ), - ImplTraitContext::TypeAliasesOpaqueTy => self.lower_opaque_impl_trait( - span, - hir::OpaqueTyOrigin::TyAlias, - *def_node_id, - bounds, - false, - itctx, - ), + &ImplTraitContext::TypeAliasesOpaqueTy { in_assoc_ty } => self + .lower_opaque_impl_trait( + span, + hir::OpaqueTyOrigin::TyAlias { in_assoc_ty }, + *def_node_id, + bounds, + false, + itctx, + ), ImplTraitContext::Universal => { let span = t.span; self.create_def( @@ -1473,6 +1480,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { /// Given a function definition like: /// /// ```rust + /// use std::fmt::Debug; + /// /// fn test<'a, T: Debug>(x: &'a T) -> impl Debug + 'a { /// x /// } @@ -1480,13 +1489,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { /// /// we will create a TAIT definition in the HIR like /// - /// ``` + /// ```rust,ignore (pseudo-Rust) /// type TestReturn<'a, T, 'x> = impl Debug + 'x /// ``` /// /// and return a type like `TestReturn<'static, T, 'a>`, so that the function looks like: /// - /// ```rust + /// ```rust,ignore (pseudo-Rust) /// fn test<'a, T: Debug>(x: &'a T) -> TestReturn<'static, T, 'a> /// ``` /// @@ -1526,13 +1535,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { // If this came from a TAIT (as opposed to a function that returns an RPIT), we only want // to capture the lifetimes that appear in the bounds. So visit the bounds to find out // exactly which ones those are. - let lifetimes_to_remap = if origin == hir::OpaqueTyOrigin::TyAlias { - // in a TAIT like `type Foo<'a> = impl Foo<'a>`, we don't keep all the lifetime parameters - Vec::new() - } else { - // in fn return position, like the `fn test<'a>() -> impl Debug + 'a` example, - // we only keep the lifetimes that appear in the `impl Debug` itself: - lifetime_collector::lifetimes_in_bounds(&self.resolver, bounds) + let lifetimes_to_remap = match origin { + hir::OpaqueTyOrigin::TyAlias { .. } => { + // in a TAIT like `type Foo<'a> = impl Foo<'a>`, we don't keep all the lifetime parameters + Vec::new() + } + hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..) => { + // in fn return position, like the `fn test<'a>() -> impl Debug + 'a` example, + // we only keep the lifetimes that appear in the `impl Debug` itself: + lifetime_collector::lifetimes_in_bounds(&self.resolver, bounds) + } }; debug!(?lifetimes_to_remap); @@ -2421,11 +2433,20 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { TraitBoundModifier::None => hir::TraitBoundModifier::None, TraitBoundModifier::MaybeConst => hir::TraitBoundModifier::MaybeConst, + TraitBoundModifier::Negative => { + if self.tcx.features().negative_bounds { + hir::TraitBoundModifier::Negative + } else { + hir::TraitBoundModifier::None + } + } + // `MaybeConstMaybe` will cause an error during AST validation, but we need to pick a // placeholder for compilation to proceed. TraitBoundModifier::MaybeConstMaybe | TraitBoundModifier::Maybe => { hir::TraitBoundModifier::Maybe } + TraitBoundModifier::MaybeConstNegative => hir::TraitBoundModifier::MaybeConst, } } |