Don't ICE if TAIT-defining fn contains a closure with _
in return type
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533cfde67c
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@ -135,18 +135,25 @@ fn check(&mut self, item_def_id: LocalDefId) {
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return;
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return;
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}
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}
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if let Some(hir_sig) = self.tcx.hir_node_by_def_id(item_def_id).fn_decl() {
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// Function items with `_` in their return type already emit an error, skip any
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if hir_sig.output.get_infer_ret_ty().is_some() {
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// "non-defining use" errors for them.
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let guar = self.tcx.dcx().span_delayed_bug(
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// Note that we use `Node::fn_sig` instead of `Node::fn_decl` here, because the former
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hir_sig.output.span(),
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// excludes closures, which are allowed to have `_` in their return type.
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"inferring return types and opaque types do not mix well",
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let hir_node = self.tcx.hir_node_by_def_id(item_def_id);
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);
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debug_assert!(
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self.found = Some(ty::OpaqueHiddenType {
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!matches!(hir_node, Node::ForeignItem(..)),
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span: DUMMY_SP,
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"foreign items cannot constrain opaque types",
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ty: Ty::new_error(self.tcx, guar),
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);
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});
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if let Some(hir_sig) = hir_node.fn_sig()
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return;
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&& hir_sig.decl.output.get_infer_ret_ty().is_some()
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}
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{
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let guar = self.tcx.dcx().span_delayed_bug(
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hir_sig.decl.output.span(),
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"inferring return types and opaque types do not mix well",
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);
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self.found =
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Some(ty::OpaqueHiddenType { span: DUMMY_SP, ty: Ty::new_error(self.tcx, guar) });
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return;
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}
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}
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// Calling `mir_borrowck` can lead to cycle errors through
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// Calling `mir_borrowck` can lead to cycle errors through
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35
tests/ui/type-alias-impl-trait/closure_infer.rs
Normal file
35
tests/ui/type-alias-impl-trait/closure_infer.rs
Normal file
@ -0,0 +1,35 @@
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// check-pass
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// Regression test for an ICE: https://github.com/rust-lang/rust/issues/119916
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#![feature(impl_trait_in_assoc_type)]
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#![feature(type_alias_impl_trait)]
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// `impl_trait_in_assoc_type` example from the bug report.
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pub trait StreamConsumer {
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type BarrierStream;
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fn execute() -> Self::BarrierStream;
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}
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pub struct DispatchExecutor;
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impl StreamConsumer for DispatchExecutor {
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type BarrierStream = impl Sized;
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fn execute() -> Self::BarrierStream {
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|| -> _ {}
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}
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}
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// Functions that constrain TAITs can contain closures with an `_` in the return type.
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type Foo = impl Sized;
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fn foo() -> Foo {
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|| -> _ {}
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}
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// The `_` in the closure return type can also be the TAIT itself.
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type Bar = impl Sized;
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fn bar() -> impl FnOnce() -> Bar {
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|| -> _ {}
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}
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fn main() {}
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