1 files changed, 26 insertions, 0 deletions
diff --git a/tests/ui/traits/fn-trait-cast-diagnostic.rs b/tests/ui/traits/fn-trait-cast-diagnostic.rs
new file mode 100644
index 000000000..e20aa210e
--- /dev/null
+++ b/tests/ui/traits/fn-trait-cast-diagnostic.rs
@@ -0,0 +1,26 @@
+// There are two different instances to check that even if
+// the trait is implemented for the output of a function,
+// it will still be displayed if the function itself implements a trait.
+trait Foo {}
+
+impl Foo for fn() -> bool {}
+impl Foo for bool {}
+
+fn example() -> bool {
+    true
+}
+
+trait NoOtherFoo {}
+
+impl NoOtherFoo for fn() -> bool {}
+
+fn do_on_foo(v: impl Foo) {}
+fn do_on_single_foo(v: impl NoOtherFoo) {}
+
+fn main() {
+    do_on_foo(example);
+    //~^ ERROR the trait bound
+
+    do_on_single_foo(example);
+    //~^ ERROR the trait bound
+}