Add test for displayed re-export of doc(hidden)

Author: GuillaumeGomez

tests/rustdoc/reexport-doc-hidden.rs

@@ -0,0 +1,26 @@
+// Part of <https://github.com/rust-lang/rust/issues/59368>.
+// This test ensures that reexporting a `doc(hidden)` item will
+// still show the reexport.
+
+#![crate_name = "foo"]
+
+#[doc(hidden)]
+pub type Type = u32;
+
+// @has 'foo/index.html'
+// @has - '//*[@id="reexport.Type2"]/code' 'pub use crate::Type as Type2;'
+pub use crate::Type as Type2;
+
+// @count - '//*[@id="reexport.Type3"]' 0
+#[doc(hidden)]
+pub use crate::Type as Type3;
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! foo {
+    () => {};
+}
+
+// This is a bug: https://github.com/rust-lang/rust/issues/59368
+// @!has - '//*[@id="reexport.Macro"]/code' 'pub use crate::foo as Macro;'
+pub use crate::foo as Macro;