bjoernager/rust
bjoernager/rust
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Ellen 2021-02-10 05:15:35 +00:00
parent 1d9ac3c22c
commit 2c4337a70a
1 changed files with 18 additions and 4 deletions
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22
compiler/rustc_typeck/src/collect/type_of.rs
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@ -29,19 +29,32 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
let parent_node = tcx.hir().get(parent_node_id); let parent_node = tcx.hir().get(parent_node_id);
match parent_node { match parent_node {
// This matches on types who's paths couldn't be resolved without typeck'ing e.g.
//
// trait Foo {
// type Assoc<const N1: usize>;;
// fn foo() -> Self::Assoc<3>;
// // note: if the def_id argument is the 3 then in this example
// // parent_node would be the node for Self::Assoc<_>
// }
// We didnt write <Self as Foo>::Assoc so the Self::Assoc<_> is lowered to QPath::TypeRelative.
// I believe this match arm is only needed for GAT but I am not 100% sure - BoxyUwU
Node::Ty(hir_ty @ Ty { kind: TyKind::Path(QPath::TypeRelative(_, segment)), .. }) => { Node::Ty(hir_ty @ Ty { kind: TyKind::Path(QPath::TypeRelative(_, segment)), .. }) => {
let id = tcx // Walk up from the parent_node to find an item so that
// we can resolve the relative path to an actual associated type
let item_hir_id = tcx
.hir() .hir()
.parent_iter(hir_id) .parent_iter(hir_id)
.filter(|(_, node)| matches!(node, Node::Item(_))) .filter(|(_, node)| matches!(node, Node::Item(_)))
.map(|(id, _)| id) .map(|(id, _)| id)
.next() .next()
.unwrap(); .unwrap();
let item_did = tcx.hir().local_def_id(item_hir_id).to_def_id();
let item_did = tcx.hir().local_def_id(id).to_def_id();
let item_ctxt = &ItemCtxt::new(tcx, item_did) as &dyn crate::astconv::AstConv<'_>; let item_ctxt = &ItemCtxt::new(tcx, item_did) as &dyn crate::astconv::AstConv<'_>;
let ty = item_ctxt.ast_ty_to_ty(hir_ty);
// This ty will be the actual associated type so that we can
// go through its generics to find which param our def_id corresponds to
let ty = item_ctxt.ast_ty_to_ty(hir_ty);
if let ty::Projection(projection) = ty.kind() { if let ty::Projection(projection) = ty.kind() {
let generics = tcx.generics_of(projection.item_def_id); let generics = tcx.generics_of(projection.item_def_id);
@ -65,6 +78,7 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
.map(|param| param.def_id); .map(|param| param.def_id);
} }
// I dont think it's possible to reach this but I'm not 100% sure - BoxyUwU
tcx.sess.delay_span_bug( tcx.sess.delay_span_bug(
tcx.def_span(def_id), tcx.def_span(def_id),
"unexpected non-GAT usage of an anon const", "unexpected non-GAT usage of an anon const",