Don't ICE if TAIT-defining fn contains a closure with _ in return type

This commit is contained in:
Lukas Markeffsky 2024-01-14 23:23:30 +01:00
parent 533cfde67c
commit 450cb5eda6
2 changed files with 54 additions and 12 deletions

View File

@ -135,18 +135,25 @@ fn check(&mut self, item_def_id: LocalDefId) {
return; return;
} }
if let Some(hir_sig) = self.tcx.hir_node_by_def_id(item_def_id).fn_decl() { // Function items with `_` in their return type already emit an error, skip any
if hir_sig.output.get_infer_ret_ty().is_some() { // "non-defining use" errors for them.
let guar = self.tcx.dcx().span_delayed_bug( // Note that we use `Node::fn_sig` instead of `Node::fn_decl` here, because the former
hir_sig.output.span(), // excludes closures, which are allowed to have `_` in their return type.
"inferring return types and opaque types do not mix well", let hir_node = self.tcx.hir_node_by_def_id(item_def_id);
); debug_assert!(
self.found = Some(ty::OpaqueHiddenType { !matches!(hir_node, Node::ForeignItem(..)),
span: DUMMY_SP, "foreign items cannot constrain opaque types",
ty: Ty::new_error(self.tcx, guar), );
}); if let Some(hir_sig) = hir_node.fn_sig()
return; && hir_sig.decl.output.get_infer_ret_ty().is_some()
} {
let guar = self.tcx.dcx().span_delayed_bug(
hir_sig.decl.output.span(),
"inferring return types and opaque types do not mix well",
);
self.found =
Some(ty::OpaqueHiddenType { span: DUMMY_SP, ty: Ty::new_error(self.tcx, guar) });
return;
} }
// Calling `mir_borrowck` can lead to cycle errors through // Calling `mir_borrowck` can lead to cycle errors through

View File

@ -0,0 +1,35 @@
// check-pass
// Regression test for an ICE: https://github.com/rust-lang/rust/issues/119916
#![feature(impl_trait_in_assoc_type)]
#![feature(type_alias_impl_trait)]
// `impl_trait_in_assoc_type` example from the bug report.
pub trait StreamConsumer {
type BarrierStream;
fn execute() -> Self::BarrierStream;
}
pub struct DispatchExecutor;
impl StreamConsumer for DispatchExecutor {
type BarrierStream = impl Sized;
fn execute() -> Self::BarrierStream {
|| -> _ {}
}
}
// Functions that constrain TAITs can contain closures with an `_` in the return type.
type Foo = impl Sized;
fn foo() -> Foo {
|| -> _ {}
}
// The `_` in the closure return type can also be the TAIT itself.
type Bar = impl Sized;
fn bar() -> impl FnOnce() -> Bar {
|| -> _ {}
}
fn main() {}