improves outer mod attribute test

Author: spencer3035

Diff for: tests/ui/attributes/outer-mod-attr-applies-only-to-first.rs

@@ -0,0 +1,16 @@
+//! Regression test to check that outer attributes applied to the first module item is applied to
+//! its attached module item only, and not also to other subsequent module items
+//!
+//! Commit: <https://github.com/rust-lang/rust/commit/7aee9f7b56f8d96f9444ebb1d06e32e024b81974>
+
+//@ check-pass
+//@ compile-flags: --cfg=first
+//@ no-auto-check-cfg
+
+#[cfg(first)]
+mod hello {}
+
+#[cfg(not_set)]
+mod hello {}
+
+fn main() {}