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Don't substitute a GAT that has mismatched generics in OpaqueTypeCollector

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This commit is contained in:
Michael Goulet 2023-06-21 05:32:35 +00:00
parent 38b44eb233
commit 5344ed23fa
6 changed files with 144 additions and 75 deletions
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42
compiler/rustc_trait_selection/src/traits/project.rs
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@ -1,5 +1,6 @@
//! Code for projecting associated types out of trait references.
use super::check_substs_compatible;
use super::specialization_graph;
use super::translate_substs;
use super::util;
@ -2378,47 +2379,6 @@ fn confirm_impl_candidate<'cx, 'tcx>(
}
}
// Verify that the trait item and its implementation have compatible substs lists
fn check_substs_compatible<'tcx>(
tcx: TyCtxt<'tcx>,
assoc_item: ty::AssocItem,
substs: ty::SubstsRef<'tcx>,
) -> bool {
fn check_substs_compatible_inner<'tcx>(
tcx: TyCtxt<'tcx>,
generics: &'tcx ty::Generics,
args: &'tcx [ty::GenericArg<'tcx>],
) -> bool {
if generics.count() != args.len() {
return false;
}
let (parent_args, own_args) = args.split_at(generics.parent_count);
if let Some(parent) = generics.parent
&& let parent_generics = tcx.generics_of(parent)
&& !check_substs_compatible_inner(tcx, parent_generics, parent_args) {
return false;
}
for (param, arg) in std::iter::zip(&generics.params, own_args) {
match (&param.kind, arg.unpack()) {
(ty::GenericParamDefKind::Type { .. }, ty::GenericArgKind::Type(_))
| (ty::GenericParamDefKind::Lifetime, ty::GenericArgKind::Lifetime(_))
| (ty::GenericParamDefKind::Const { .. }, ty::GenericArgKind::Const(_)) => {}
_ => return false,
}
}
true
}
let generics = tcx.generics_of(assoc_item.def_id);
// Chop off any additional substs (RPITIT) substs
let substs = &substs[0..generics.count().min(substs.len())];
check_substs_compatible_inner(tcx, generics, substs)
}
fn confirm_impl_trait_in_trait_candidate<'tcx>(
selcx: &mut SelectionContext<'_, 'tcx>,
obligation: &ProjectionTyObligation<'tcx>,