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Only use the parent if it's an opaque type

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Aaron Hill 2020-02-10 23:35:49 -05:00
parent a60669d95c
commit 34cf0b3267
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GPG Key ID: B4087E510E98B164
1 changed files with 11 additions and 3 deletions
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14
src/librustc_typeck/collect.rs
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@ -1057,11 +1057,19 @@ fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::Generics {
ItemKind::OpaqueTy(hir::OpaqueTy { impl_trait_fn, .. }) => {
impl_trait_fn.or_else(|| {
let parent_id = tcx.hir().get_parent_item(hir_id);
// This opaque type might occur inside another opaque type
// (e.g. `impl Foo<MyType = impl Bar<A>>`)
if parent_id != hir_id && parent_id != CRATE_HIR_ID {
debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
Some(tcx.hir().local_def_id(parent_id))
// If this 'impl Trait' is nested inside another 'impl Trait'
// (e.g. `impl Foo<MyType = impl Bar<A>>`), we need to use the 'parent'
// 'impl Trait' for its generic parameters, since we can reference them
// from the 'child' 'impl Trait'
if let Node::Item(hir::Item { kind: ItemKind::OpaqueTy(..), .. }) =
tcx.hir().get(parent_id)
{
Some(tcx.hir().local_def_id(parent_id))
} else {
None
}
} else {
None
}