Add regression test for doc of reexport of local items

src/test/rustdoc/local-reexport-doc.rs

@@ -0,0 +1,16 @@
+// This test ensures that the reexports of local items also get the doc from
+// the reexport.
+
+#![crate_name = "foo"]
+
+// @has 'foo/fn.g.html'
+// @has - '//*[@class="rustdoc-toggle top-doc"]/*[@class="docblock"]' \
+// 'outer module inner module'
+
+mod inner_mod {
+    /// inner module
+    pub fn g() {}
+}
+
+/// outer module
+pub use inner_mod::g;