rustdoc: Record crate name instead of using None

Author: camelid

src/librustdoc/visit_ast.rs

@@ -76,7 +76,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
             &Spanned { span: rustc_span::DUMMY_SP, node: hir::VisibilityKind::Public },
             hir::CRATE_HIR_ID,
             &krate.item.module,
-            None,
+            Some(self.cx.tcx.crate_name),
         );
         top_level_module.is_crate = true;
         // Attach the crate's exported macros to the top-level module.

src/test/rustdoc-ui/intra-doc/private-from-crate-level.rs

@@ -0,0 +1,6 @@
+// check-pass
+
+//! [my_module]
+//~^ WARN public documentation for `private_from_crate_level` links to private item `my_module`
+
+mod my_module {}

src/test/rustdoc-ui/intra-doc/private-from-crate-level.stderr

@@ -0,0 +1,11 @@
+warning: public documentation for `private_from_crate_level` links to private item `my_module`
+  --> $DIR/private-from-crate-level.rs:3:6
+   |
+LL | //! [my_module]
+   |      ^^^^^^^^^ this item is private
+   |
+   = note: `#[warn(rustdoc::private_intra_doc_links)]` on by default
+   = note: this link will resolve properly if you pass `--document-private-items`
+
+warning: 1 warning emitted
+