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Add hint for missing lifetime bound on trait object when type alias is used

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This commit is contained in:
yanchen4791
2022-12-05 16:51:49 -08:00
parent c8e6a9e8b6
commit 62a1e76d2b
6 changed files with 176 additions and 19 deletions
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24
compiler/rustc_middle/src/ty/context.rs
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@@ -997,6 +997,30 @@ impl<'tcx> TyCtxt<'tcx> {
v.0
}
/// Given a `DefId` for an `fn`, return all the `dyn` and `impl` traits in its return type and associated alias span when type alias is used
pub fn return_type_impl_or_dyn_traits_with_type_alias(
self,
scope_def_id: LocalDefId,
) -> Option<(Vec<&'tcx hir::Ty<'tcx>>, Span)> {
let hir_id = self.hir().local_def_id_to_hir_id(scope_def_id);
let mut v = TraitObjectVisitor(vec![], self.hir());
// when the return type is a type alias
if let Some(hir::FnDecl { output: hir::FnRetTy::Return(hir_output), .. }) = self.hir().fn_decl_by_hir_id(hir_id)
&& let hir::TyKind::Path(hir::QPath::Resolved(
None,
hir::Path { res: hir::def::Res::Def(DefKind::TyAlias, def_id), .. }, )) = hir_output.kind
&& let Some(local_id) = def_id.as_local()
&& let Some(alias_ty) = self.hir().get_by_def_id(local_id).alias_ty() // it is type alias
&& let Some(alias_generics) = self.hir().get_by_def_id(local_id).generics()
{
v.visit_ty(alias_ty);
if !v.0.is_empty() {
return Some((v.0, alias_generics.span));
}
}
return None;
}
pub fn return_type_impl_trait(self, scope_def_id: LocalDefId) -> Option<(Ty<'tcx>, Span)> {
// `type_of()` will fail on these (#55796, #86483), so only allow `fn`s or closures.
match self.hir().get_by_def_id(scope_def_id) {