rustdoc: load the set of in-scope traits for modules with no docstring

Fixes #93428

This fix is a response to a couple of special cases related to the
`module_id`, which is eventually used for trait candidates:

  * The module id is always set to the current crate, when checking `crate::`.

    Normally, the set of in-scope traits would be set in `load_links_in_attrs`,
    but if there are no doc comments, then that loop will never run.

  * the module id is set to the parent module, when resolving a module
    that is spelled like this:

        // Notice how we use an outlined doc comment here!
        // [`Test::my_fn`]
        mod something {
        }

    As with the above problem with `crate::`, we need to make sure the
    module gets its traits in scope resolved, even if it has no doc comments
    of its own.

1 files changed, 17 insertions, 0 deletions

diff --git a/src/test/rustdoc/intra-doc/mod-relative.rs b/src/test/rustdoc/intra-doc/mod-relative.rs
new file mode 100644
index 00000000000..49d3399b972
--- /dev/null
+++ b/src/test/rustdoc/intra-doc/mod-relative.rs
@@ -0,0 +1,17 @@
+pub mod wrapper {
+
+    pub struct Test<'a> {
+        data: &'a (),
+    }
+
+    impl<'a> Test<'a> {
+        pub fn do_test(&self) {}
+    }
+
+    // @has mod_relative/wrapper/demo/index.html
+    // @has - '//a/@href' '../struct.Test.html#method.do_test'
+    /// [`Test::do_test`]
+    pub mod demo {
+    }
+
+}