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Consider principal trait ref's auto-trait super-traits in dyn upcasting

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This commit is contained in:
Michael Goulet 2023-12-27 03:17:37 +00:00
parent fa9f77ff35
commit ec8e898193
4 changed files with 93 additions and 52 deletions
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13
compiler/rustc_trait_selection/src/traits/select/mod.rs
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@ -2526,6 +2526,17 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
let tcx = self.tcx();
let mut nested = vec![];
// We may upcast to auto traits that are either explicitly listed in
// the object type's bounds, or implied by the principal trait ref's
// supertraits.
let a_auto_traits: FxIndexSet<DefId> = a_data
.auto_traits()
.chain(a_data.principal_def_id().into_iter().flat_map(|principal_def_id| {
util::supertrait_def_ids(tcx, principal_def_id)
.filter(|def_id| tcx.trait_is_auto(*def_id))
}))
.collect();
let upcast_principal = normalize_with_depth_to(
self,
obligation.param_env,
@ -2588,7 +2599,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
}
// Check that b_ty's auto traits are present in a_ty's bounds.
ty::ExistentialPredicate::AutoTrait(def_id) => {
if !a_data.auto_traits().any(|source_def_id| source_def_id == def_id) {
if !a_auto_traits.contains(&def_id) {
return Err(SelectionError::Unimplemented);
}
}