diff options
| -rw-r--r-- | compiler/rustc_infer/src/infer/opaque_types.rs | 9 | ||||
| -rw-r--r-- | src/test/ui/impl-trait/example-calendar.rs | 3 | ||||
| -rw-r--r-- | src/test/ui/impl-trait/example-calendar.stderr | 19 |
3 files changed, 10 insertions, 21 deletions
diff --git a/compiler/rustc_infer/src/infer/opaque_types.rs b/compiler/rustc_infer/src/infer/opaque_types.rs index 35104c71bfc..46420fbe0c3 100644 --- a/compiler/rustc_infer/src/infer/opaque_types.rs +++ b/compiler/rustc_infer/src/infer/opaque_types.rs @@ -82,7 +82,14 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> { let process = |a: Ty<'tcx>, b: Ty<'tcx>| match *a.kind() { ty::Opaque(def_id, substs) => { if let ty::Opaque(did2, _) = *b.kind() { - if self.opaque_type_origin(did2, cause.span).is_some() { + // We could accept this, but there are various ways to handle this situation, and we don't + // want to make a decision on it right now. Likely this case is so super rare anyway, that + // no one encounters it in practice. + // It does occur however in `fn fut() -> impl Future<Output = i32> { async { 42 } }`, + // where it is of no concern, so we only check for TAITs. + if let Some(OpaqueTyOrigin::TyAlias) = + self.opaque_type_origin(did2, cause.span) + { self.tcx .sess .struct_span_err( diff --git a/src/test/ui/impl-trait/example-calendar.rs b/src/test/ui/impl-trait/example-calendar.rs index 26618eec1d7..45dcb74a6e0 100644 --- a/src/test/ui/impl-trait/example-calendar.rs +++ b/src/test/ui/impl-trait/example-calendar.rs @@ -1,3 +1,4 @@ +// run-pass // ignore-compare-mode-chalk #![feature(fn_traits, @@ -589,7 +590,7 @@ fn test_format_month() { fn format_months(it: impl Iterator<Item = impl DateIterator>) -> impl Iterator<Item=impl Iterator<Item=String>> { - it.map(format_month) //~ ERROR opaque type's hidden type cannot be another opaque type + it.map(format_month) } /// Takes an iterator of iterators of strings; the sub-iterators are consumed diff --git a/src/test/ui/impl-trait/example-calendar.stderr b/src/test/ui/impl-trait/example-calendar.stderr deleted file mode 100644 index 3894285947f..00000000000 --- a/src/test/ui/impl-trait/example-calendar.stderr +++ /dev/null @@ -1,19 +0,0 @@ -error: opaque type's hidden type cannot be another opaque type from the same scope - --> $DIR/example-calendar.rs:592:5 - | -LL | it.map(format_month) - | ^^^^^^^^^^^^^^^^^^^^ one of the two opaque types used here has to be outside its defining scope - | -note: opaque type whose hidden type is being assigned - --> $DIR/example-calendar.rs:560:43 - | -LL | fn format_month(it: impl DateIterator) -> impl Iterator<Item=String> { - | ^^^^^^^^^^^^^^^^^^^^^^^^^^ -note: opaque type being used as hidden type - --> $DIR/example-calendar.rs:590:39 - | -LL | -> impl Iterator<Item=impl Iterator<Item=String>> - | ^^^^^^^^^^^^^^^^^^^^^^^^^^ - -error: aborting due to previous error - |