1 files changed, 20 insertions, 0 deletions
diff --git a/tests/ui/type-alias-impl-trait/hidden_behind_projection_behind_struct_field.stderr b/tests/ui/type-alias-impl-trait/hidden_behind_projection_behind_struct_field.stderr
new file mode 100644
index 000000000..00aedfae4
--- /dev/null
+++ b/tests/ui/type-alias-impl-trait/hidden_behind_projection_behind_struct_field.stderr
@@ -0,0 +1,20 @@
+error[E0308]: mismatched types
+  --> $DIR/hidden_behind_projection_behind_struct_field.rs:19:22
+   |
+LL |     type Assoc = impl std::fmt::Debug;
+   |                  -------------------- the expected opaque type
+LL |     fn foo() -> Foo<Bar> {
+LL |         Foo { field: () }
+   |                      ^^ expected opaque type, found `()`
+   |
+   = note: expected opaque type `<Bar as Trait>::Assoc`
+                found unit type `()`
+note: this item must have the opaque type in its signature in order to be able to register hidden types
+  --> $DIR/hidden_behind_projection_behind_struct_field.rs:18:8
+   |
+LL |     fn foo() -> Foo<Bar> {
+   |        ^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.