diff options
| -rw-r--r-- | compiler/rustc_ast_lowering/src/item.rs | 132 |
1 files changed, 62 insertions, 70 deletions
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs index 1784e4a6c63..ad22418eb7d 100644 --- a/compiler/rustc_ast_lowering/src/item.rs +++ b/compiler/rustc_ast_lowering/src/item.rs @@ -46,11 +46,59 @@ fn add_ty_alias_where_clause( } impl ItemLowerer<'_, '_, '_> { - fn with_trait_impl_ref<T>( + /// Clears (and restores) the `in_scope_lifetimes` field. Used when + /// visiting nested items, which never inherit in-scope lifetimes + /// from their surrounding environment. + #[tracing::instrument(level = "debug", skip(self, f))] + fn without_in_scope_lifetime_defs<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T { + let old_in_scope_lifetimes = mem::take(&mut self.lctx.in_scope_lifetimes); + debug!(?old_in_scope_lifetimes); + + // this vector is only used when walking over impl headers, + // input types, and the like, and should not be non-empty in + // between items + assert!(self.lctx.lifetimes_to_define.is_empty()); + + let res = f(self); + + assert!(self.lctx.in_scope_lifetimes.is_empty()); + self.lctx.in_scope_lifetimes = old_in_scope_lifetimes; + + res + } + + /// Evaluates `f` with the lifetimes in `params` in-scope. + /// This is used to track which lifetimes have already been defined, and + /// which are new in-band lifetimes that need to have a definition created + /// for them. + fn with_parent_item_lifetime_defs( &mut self, - impl_ref: &Option<TraitRef>, - f: impl FnOnce(&mut Self) -> T, - ) -> T { + parent_item: LocalDefId, + f: impl FnOnce(&mut Self), + ) { + let parent_hir = self.lctx.owners[parent_item].unwrap().node().expect_item(); + let parent_generics = match parent_hir.kind { + hir::ItemKind::Impl(hir::Impl { ref generics, .. }) + | hir::ItemKind::Trait(_, _, ref generics, ..) => generics.params, + _ => &[], + }; + let lt_def_names = parent_generics + .iter() + .filter_map(|param| match param.kind { + hir::GenericParamKind::Lifetime { .. } => { + Some(param.name.normalize_to_macros_2_0()) + } + _ => None, + }) + .collect(); + let old_in_scope_lifetimes = mem::replace(&mut self.lctx.in_scope_lifetimes, lt_def_names); + + f(self); + + self.lctx.in_scope_lifetimes = old_in_scope_lifetimes; + } + + fn with_trait_impl_ref(&mut self, impl_ref: &Option<TraitRef>, f: impl FnOnce(&mut Self)) { let old = self.lctx.is_in_trait_impl; self.lctx.is_in_trait_impl = impl_ref.is_some(); let ret = f(self); @@ -66,20 +114,19 @@ impl<'a> Visitor<'a> for ItemLowerer<'a, '_, '_> { } fn visit_item(&mut self, item: &'a Item) { - let hir_id = self.lctx.with_hir_id_owner(item.id, |lctx| { - let node = lctx.without_in_scope_lifetime_defs(|lctx| lctx.lower_item(item)); - hir::OwnerNode::Item(node) + let hir_id = self.without_in_scope_lifetime_defs(|this| { + this.lctx.with_hir_id_owner(item.id, |lctx| { + let node = lctx.lower_item(item); + hir::OwnerNode::Item(node) + }) }); - self.lctx.with_parent_item_lifetime_defs(hir_id, |this| { - let this = &mut ItemLowerer { lctx: this }; - match item.kind { - ItemKind::Impl(box Impl { ref of_trait, .. }) => { - this.with_trait_impl_ref(of_trait, |this| visit::walk_item(this, item)); - } - _ => visit::walk_item(this, item), + self.with_parent_item_lifetime_defs(hir_id, |this| match item.kind { + ItemKind::Impl(box Impl { ref of_trait, .. }) => { + this.with_trait_impl_ref(of_trait, |this| visit::walk_item(this, item)); } - }); + _ => visit::walk_item(this, item), + }) } fn visit_fn(&mut self, fk: FnKind<'a>, sp: Span, _: NodeId) { @@ -114,61 +161,6 @@ impl<'a> Visitor<'a> for ItemLowerer<'a, '_, '_> { } impl<'hir> LoweringContext<'_, 'hir> { - // Same as the method above, but accepts `hir::GenericParam`s - // instead of `ast::GenericParam`s. - // This should only be used with generics that have already had their - // in-band lifetimes added. In practice, this means that this function is - // only used when lowering a child item of a trait or impl. - #[tracing::instrument(level = "debug", skip(self, f))] - fn with_parent_item_lifetime_defs<T>( - &mut self, - parent_hir_id: LocalDefId, - f: impl FnOnce(&mut Self) -> T, - ) -> T { - let parent_generics = match self.owners[parent_hir_id].unwrap().node().expect_item().kind { - hir::ItemKind::Impl(hir::Impl { ref generics, .. }) - | hir::ItemKind::Trait(_, _, ref generics, ..) => generics.params, - _ => &[], - }; - let lt_def_names = parent_generics - .iter() - .filter_map(|param| match param.kind { - hir::GenericParamKind::Lifetime { .. } => { - Some(param.name.normalize_to_macros_2_0()) - } - _ => None, - }) - .collect(); - let old_in_scope_lifetimes = mem::replace(&mut self.in_scope_lifetimes, lt_def_names); - debug!(in_scope_lifetimes = ?self.in_scope_lifetimes); - - let res = f(self); - - self.in_scope_lifetimes = old_in_scope_lifetimes; - res - } - - // Clears (and restores) the `in_scope_lifetimes` field. Used when - // visiting nested items, which never inherit in-scope lifetimes - // from their surrounding environment. - #[tracing::instrument(level = "debug", skip(self, f))] - fn without_in_scope_lifetime_defs<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T { - let old_in_scope_lifetimes = mem::replace(&mut self.in_scope_lifetimes, vec![]); - debug!(?old_in_scope_lifetimes); - - // this vector is only used when walking over impl headers, - // input types, and the like, and should not be non-empty in - // between items - assert!(self.lifetimes_to_define.is_empty()); - - let res = f(self); - - assert!(self.in_scope_lifetimes.is_empty()); - self.in_scope_lifetimes = old_in_scope_lifetimes; - - res - } - pub(super) fn lower_mod(&mut self, items: &[P<Item>], inner: Span) -> hir::Mod<'hir> { hir::Mod { inner: self.lower_span(inner), |