Add test for issue-60390

Author: JohnTitor

src/test/ui/mir/issue-60390.rs

@@ -0,0 +1,8 @@
+// check-pass
+// compile-flags: --emit=mir,link
+// Regression test for #60390, this ICE requires `--emit=mir` flag.
+
+fn main() {
+    enum Inner { Member(u32) };
+    Inner::Member(0);
+}