Avoid documenting top-level private imports

Author: inquisitivecrystal

src/librustdoc/clean/mod.rs

@@ -1938,8 +1938,20 @@ fn clean_use_statement(
     let inline_attr = attrs.lists(sym::doc).get_word_attr(sym::inline);
     let pub_underscore = visibility.is_public() && name == kw::Underscore;
     let current_mod = cx.tcx.parent_module_from_def_id(import.def_id);
+
+    // The parent of the module in which this import resides. This
+    // is the same as `current_mod` if that's already the top
+    // level module.
     let parent_mod = cx.tcx.parent_module_from_def_id(current_mod);
 
+    // This checks if the import can be seen from a higher level module.
+    // In other words, it checks if the visibility is the equivalent of
+    // `pub(super)` or higher. If the current module is the top level
+    // module, there isn't really a parent module, which makes the results
+    // meaningless. In this case, we make sure the answer is `false`.
+    let is_visible_from_parent_mod = visibility.is_accessible_from(parent_mod.to_def_id(), cx.tcx)
+        && !current_mod.is_top_level_module();
+
     if pub_underscore {
         if let Some(ref inline) = inline_attr {
             rustc_errors::struct_span_err!(
@@ -1958,8 +1970,7 @@ fn clean_use_statement(
     // #[doc(no_inline)] attribute is present.
     // Don't inline doc(hidden) imports so they can be stripped at a later stage.
     let mut denied = !(visibility.is_public()
-        || (cx.render_options.document_private
-            && visibility.is_accessible_from(parent_mod.to_def_id(), cx.tcx)))
+        || (cx.render_options.document_private && is_visible_from_parent_mod))
         || pub_underscore
         || attrs.iter().any(|a| {
             a.has_name(sym::doc)