1 files changed, 30 insertions, 0 deletions
diff --git a/tests/ui/type-alias-impl-trait/hidden_behind_struct_field.rs b/tests/ui/type-alias-impl-trait/hidden_behind_struct_field.rs
new file mode 100644
index 000000000..58778702d
--- /dev/null
+++ b/tests/ui/type-alias-impl-trait/hidden_behind_struct_field.rs
@@ -0,0 +1,30 @@
+//! This test shows that the appearance of an opaque type
+//! in the substs of a struct are enough to make it count
+//! for making the function a defining use. It doesn't matter
+//! if the opaque type is actually used in the field.
+
+#![feature(impl_trait_in_assoc_type)]
+// check-pass
+
+use std::marker::PhantomData;
+
+struct Bar;
+
+trait Trait: Sized {
+    type Assoc;
+    fn foo() -> Foo<Self::Assoc>;
+}
+
+impl Trait for Bar {
+    type Assoc = impl std::fmt::Debug;
+    fn foo() -> Foo<Self::Assoc> {
+        let foo: Foo<()> = Foo { field: PhantomData };
+        foo
+    }
+}
+
+struct Foo<T> {
+    field: PhantomData<T>,
+}
+
+fn main() {}