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TAIT: feature gate recursive locations

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This commit is contained in:
Mazdak Farrokhzad 2019-11-07 17:59:58 +01:00
parent 6a49b523be
commit 6d8e300e35
1 changed files with 26 additions and 20 deletions
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46
src/libsyntax/feature_gate/check.rs
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@ -318,6 +318,27 @@ fn check_gat(&self, generics: &ast::Generics, span: Span) {
);
}
}
/// Feature gate `impl Trait` inside `type Alias = $type_expr;`.
fn check_impl_trait(&self, ty: &ast::Ty) {
struct ImplTraitVisitor<'a> {
vis: &'a PostExpansionVisitor<'a>,
}
impl Visitor<'_> for ImplTraitVisitor<'_> {
fn visit_ty(&mut self, ty: &ast::Ty) {
if let ast::TyKind::ImplTrait(..) = ty.kind {
gate_feature_post!(
&self.vis,
type_alias_impl_trait,
ty.span,
"`impl Trait` in type aliases is unstable"
);
}
visit::walk_ty(self, ty);
}
}
ImplTraitVisitor { vis: self }.visit_ty(ty);
}
}
impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
@ -452,14 +473,7 @@ fn visit_item(&mut self, i: &'a ast::Item) {
gate_feature_post!(&self, decl_macro, i.span, msg);
}
ast::ItemKind::OpaqueTy(..) => {
gate_feature_post!(
&self,
type_alias_impl_trait,
i.span,
"`impl Trait` in type aliases is unstable"
);
}
ast::ItemKind::TyAlias(ref ty, ..) => self.check_impl_trait(&ty),
_ => {}
}
@ -633,9 +647,8 @@ fn visit_trait_item(&mut self, ti: &'a ast::TraitItem) {
}
}
ast::TraitItemKind::Type(_, ref default) => {
// We use three if statements instead of something like match guards so that all
// of these errors can be emitted if all cases apply.
if default.is_some() {
if let Some(ty) = default {
self.check_impl_trait(ty);
gate_feature_post!(&self, associated_type_defaults, ti.span,
"associated type defaults are unstable");
}
@ -660,15 +673,8 @@ fn visit_impl_item(&mut self, ii: &'a ast::ImplItem) {
"C-variadic functions are unstable");
}
}
ast::ImplItemKind::OpaqueTy(..) => {
gate_feature_post!(
&self,
type_alias_impl_trait,
ii.span,
"`impl Trait` in type aliases is unstable"
);
}
ast::ImplItemKind::TyAlias(_) => {
ast::ImplItemKind::TyAlias(ref ty) => {
self.check_impl_trait(ty);
self.check_gat(&ii.generics, ii.span);
}
_ => {}