add regression test for closure return ICE

tests/ui/closures/return-in-closure-with-fn-bound.rs

@@ -0,0 +1,8 @@
+// Regression test for https://github.com/rust-lang/rust/issues/155893.
+
+fn func(_f: impl Fn()) {
+    func(|| return 2)
+    //~^ ERROR mismatched types
+}
+
+fn main() {}

tests/ui/closures/return-in-closure-with-fn-bound.stderr

@@ -0,0 +1,15 @@
+error[E0308]: mismatched types
+  --> $DIR/return-in-closure-with-fn-bound.rs:4:20
+   |
+LL |     func(|| return 2)
+   |                    ^ expected `()`, found integer
+   |
+note: return type inferred to be `()` here
+  --> $DIR/return-in-closure-with-fn-bound.rs:4:20
+   |
+LL |     func(|| return 2)
+   |                    ^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.