bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Auto merge of #96715 - cjgillot:trait-alias-loop, r=compiler-errors

Browse source 
Fortify handing of where bounds on trait & trait alias definitions

Closes https://github.com/rust-lang/rust/issues/96664
Closes https://github.com/rust-lang/rust/issues/96665

Since https://github.com/rust-lang/rust/pull/93803, when listing all bounds and predicates we now need to account for the possible presence of predicates on any of the generic parameters.  Both bugs were hidden by the special handling of bounds at  the generic parameter declaration position.

Trait alias expansion used to confuse predicates on `Self` and where predicates.
Exiting too late when listing all the bounds caused a cycle error.
This commit is contained in:
bors 2022-05-10 00:40:57 +00:00
commit 362010d6be
10 changed files with 69 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

3
compiler/rustc_trait_selection/src/traits/util.rs
View file

@ -118,13 +118,14 @@ impl<'tcx> TraitAliasExpander<'tcx> {
// Get components of trait alias.
let predicates = tcx.super_predicates_of(trait_ref.def_id());
debug!(?predicates);
let items = predicates.predicates.iter().rev().filter_map(|(pred, span)| {
pred.subst_supertrait(tcx, &trait_ref)
.to_opt_poly_trait_pred()
.map(|trait_ref| item.clone_and_push(trait_ref.map_bound(|t| t.trait_ref), *span))
});
debug!("expand_trait_aliases: items={:?}", items.clone());
debug!("expand_trait_aliases: items={:?}", items.clone().collect::<Vec<_>>());
self.stack.extend(items);