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This can't happen anymore. An opaque type can't end up with itself as its hidden type

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This commit is contained in:
Oli Scherer 2022-01-27 14:19:54 +00:00
parent 3146c961fe
commit 94d6a9acc9
1 changed files with 4 additions and 37 deletions
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41
compiler/rustc_borrowck/src/type_check/mod.rs
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@ -193,9 +193,9 @@ pub(crate) fn type_check<'mir, 'tcx>(
let opaque_type_values = let opaque_type_values =
infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types(); infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
let opaque_type_values = opaque_type_values opaque_type_values
.into_iter() .into_iter()
.filter_map(|(opaque_type_key, decl)| { .map(|(opaque_type_key, decl)| {
cx.fully_perform_op( cx.fully_perform_op(
Locations::All(body.span), Locations::All(body.span),
ConstraintCategory::OpaqueType, ConstraintCategory::OpaqueType,
@ -226,43 +226,10 @@ pub(crate) fn type_check<'mir, 'tcx>(
); );
hidden_type = infcx.tcx.ty_error(); hidden_type = infcx.tcx.ty_error();
} }
let concrete_is_opaque = if let ty::Opaque(def_id, _) = hidden_type.kind() {
*def_id == opaque_type_key.def_id
} else {
false
};
if concrete_is_opaque { (opaque_type_key, (hidden_type, decl.hidden_type.span, decl.origin))
// We're using an opaque `impl Trait` type without
// 'revealing' it. For example, code like this:
//
// type Foo = impl Debug;
// fn foo1() -> Foo { ... }
// fn foo2() -> Foo { foo1() }
//
// In `foo2`, we're not revealing the type of `Foo` - we're
// just treating it as the opaque type.
//
// When this occurs, we do *not* want to try to equate
// the concrete type with the underlying defining type
// of the opaque type - this will always fail, since
// the defining type of an opaque type is always
// some other type (e.g. not itself)
// Essentially, none of the normal obligations apply here -
// we're just passing around some unknown opaque type,
// without actually looking at the underlying type it
// gets 'revealed' into
debug!(
"eq_opaque_type_and_type: non-defining use of {:?}",
opaque_type_key.def_id,
);
None
} else {
Some((opaque_type_key, (hidden_type, decl.hidden_type.span, decl.origin)))
}
}) })
.collect(); .collect()
opaque_type_values
}, },
); );