Add test for doc(hidden) intra-doc cross-crate reexports

Author: Manishearth

src/test/rustdoc/intra-doc-crate/auxiliary/hidden.rs

@@ -0,0 +1,19 @@
+#![crate_name = "hidden_dep"]
+#![deny(intra_doc_resolution_failure)]
+
+#[doc(hidden)]
+pub mod __reexport {
+    pub use crate::*;
+}
+
+pub mod future {
+    mod ready {
+
+        /// Link to [`ready`](function@ready)
+        pub struct Ready;
+        pub fn ready() {}
+
+    }
+    pub use self::ready::{ready, Ready};
+
+}

src/test/rustdoc/intra-doc-crate/hidden.rs

@@ -0,0 +1,10 @@
+// aux-build:hidden.rs
+// build-aux-docs
+#![deny(intra_doc_resolution_failure)]
+
+// tests https://github.com/rust-lang/rust/issues/73363
+
+extern crate hidden_dep;
+
+// @has 'hidden/struct.Ready.html' '//a/@href' '../hidden/fn.ready.html'
+pub use hidden_dep::future::{ready, Ready};