Add test for reexports attr merge

tests/rustdoc/reexport-attr-merge.rs

@@ -0,0 +1,26 @@
+// Regression test for <https://github.com/rust-lang/rust/issues/59368>.
+// The goal is to ensure that `doc(hidden)`, `doc(inline)` and `doc(no_inline`)
+
+#![crate_name = "foo"]
+#![feature(doc_cfg)]
+
+// @has 'foo/index.html'
+
+#[doc(hidden, cfg(feature = "foo"))]
+pub struct Foo;
+
+#[doc(hidden, no_inline, cfg(feature = "bar"))]
+pub use Foo as Foo1;
+
+#[doc(hidden, inline)]
+pub use Foo1 as Foo2;
+
+// First we ensure that none of the other items are generated.
+// @count - '//a[@class="struct"]' 1
+// Then we check that both `cfg` are displayed.
+// @has - '//*[@class="stab portability"]' 'foo'
+// @has - '//*[@class="stab portability"]' 'bar'
+// And finally we check that the only element displayed is `Bar`.
+// @has - '//a[@class="struct"]' 'Bar'
+#[doc(inline)]
+pub use Foo2 as Bar;