Regression test for issue 154800

Co-authored-by: Edvin Bryntesson <epost@edvinbryntesson.se>

tests/ui/lint/malformed-expect.rs

@@ -0,0 +1,9 @@
+// Regression test for #154800 and #154847
+//@ compile-flags: --crate-type=lib
+//@ check-pass
+
+#[expect]
+#[cfg(false)]
+fn main() {
+    let _ : fn(#[expect[]] i32);
+}