bjoernager/rust
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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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80
compiler/rustc_ty_utils/src/opaque_types.rs
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@ -6,7 +6,7 @@ use rustc_middle::ty::util::{CheckRegions, NotUniqueParam};
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::ty::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
use rustc_span::Span;
use rustc_type_ir::AliasKind;
use rustc_trait_selection::traits::check_substs_compatible;
use std::ops::ControlFlow;
use crate::errors::{DuplicateArg, NotParam};
@ -36,6 +36,15 @@ impl<'tcx> OpaqueTypeCollector<'tcx> {
self.tcx.def_span(self.item)
}
fn parent_trait_ref(&self) -> Option<ty::TraitRef<'tcx>> {
let parent = self.parent()?;
if matches!(self.tcx.def_kind(parent), DefKind::Impl { .. }) {
Some(self.tcx.impl_trait_ref(parent)?.subst_identity())
} else {
None
}
}
fn parent(&self) -> Option<LocalDefId> {
match self.tcx.def_kind(self.item) {
DefKind::Fn => None,
@ -56,7 +65,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for OpaqueTypeCollector<'tcx> {
#[instrument(skip(self), ret, level = "trace")]
fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<ErrorGuaranteed> {
match t.kind() {
ty::Alias(AliasKind::Opaque, alias_ty) if alias_ty.def_id.is_local() => {
ty::Alias(ty::Opaque, alias_ty) if alias_ty.def_id.is_local() => {
if !self.seen.insert(alias_ty.def_id.expect_local()) {
return ControlFlow::Continue(());
}
@ -98,37 +107,48 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for OpaqueTypeCollector<'tcx> {
}
}
}
ty::Alias(AliasKind::Projection, alias_ty) => {
if let Some(parent) = self.parent() {
trace!(?alias_ty);
let (trait_ref, own_substs) = alias_ty.trait_ref_and_own_substs(self.tcx);
ty::Alias(ty::Projection, alias_ty) => {
// This avoids having to do normalization of `Self::AssocTy` by only
// supporting the case of a method defining opaque types from assoc types
// in the same impl block.
if let Some(parent_trait_ref) = self.parent_trait_ref() {
// If the trait ref of the associated item and the impl differs,
// then we can't use the impl's identity substitutions below, so
// just skip.
if alias_ty.trait_ref(self.tcx) == parent_trait_ref {
let parent = self.parent().expect("we should have a parent here");
trace!(?trait_ref, ?own_substs);
// This avoids having to do normalization of `Self::AssocTy` by only
// supporting the case of a method defining opaque types from assoc types
// in the same impl block.
if trait_ref.self_ty() == self.tcx.type_of(parent).subst_identity() {
for assoc in self.tcx.associated_items(parent).in_definition_order() {
for &assoc in self.tcx.associated_items(parent).in_definition_order() {
trace!(?assoc);
if assoc.trait_item_def_id == Some(alias_ty.def_id) {
// We reconstruct the generic args of the associated type within the impl
// from the impl's generics and the generic args passed to the type via the
// projection.
let substs = ty::InternalSubsts::identity_for_item(
self.tcx,
parent.to_def_id(),
);
trace!(?substs);
let substs: Vec<_> =
substs.iter().chain(own_substs.iter().copied()).collect();
trace!(?substs);
// Find opaque types in this associated type.
return self
.tcx
.type_of(assoc.def_id)
.subst(self.tcx, &substs)
.visit_with(self);
if assoc.trait_item_def_id != Some(alias_ty.def_id) {
continue;
}
// If the type is further specializable, then the type_of
// is not actually correct below.
if !assoc.defaultness(self.tcx).is_final() {
continue;
}
let impl_substs = alias_ty.substs.rebase_onto(
self.tcx,
parent_trait_ref.def_id,
ty::InternalSubsts::identity_for_item(self.tcx, parent),
);
if !check_substs_compatible(self.tcx, assoc, impl_substs) {
self.tcx.sess.delay_span_bug(
self.tcx.def_span(assoc.def_id),
"item had incorrect substs",
);
return ControlFlow::Continue(());
}
return self
.tcx
.type_of(assoc.def_id)
.subst(self.tcx, impl_substs)
.visit_with(self);
}
}
}