nr2.0: Improve visibility path handling

gcc/rust/resolve/rust-forever-stack.h

@@ -543,6 +543,13 @@ class ForeverStackStore
   Node root;
 };
 
+enum class ResolutionMode
+{
+  Normal,
+  FromRoot,
+  FromExtern, // extern prelude
+};
+
 template <Namespace N> class ForeverStack
 {
 public:
@@ -672,7 +679,7 @@ template <Namespace N> class ForeverStack
    */
   template <typename S>
   tl::optional<Rib::Definition> resolve_path (
-    const std::vector<S> &segments, bool has_opening_scope_resolution,
+    const std::vector<S> &segments, ResolutionMode mode,
     std::function<void (const S &, NodeId)> insert_segment_resolution,
     std::vector<Error> &collect_errors);
 
@@ -739,6 +746,9 @@ template <Namespace N> class ForeverStack
     tl::optional<Node &> parent; // `None` only if the node is a root
   };
 
+  // private overload which allows specifying a starting point
+  tl::optional<Rib::Definition> get (Node &start, const Identifier &name);
+
   /* Should we keep going upon seeing a Rib? */
   enum class KeepGoing
   {

gcc/rust/resolve/rust-forever-stack.hxx

@@ -291,12 +291,12 @@ ForeverStack<N>::update_cursor (Node &new_cursor)
 
 template <Namespace N>
 tl::optional<Rib::Definition>
-ForeverStack<N>::get (const Identifier &name)
+ForeverStack<N>::get (Node &start, const Identifier &name)
 {
   tl::optional<Rib::Definition> resolved_definition = tl::nullopt;
 
   // TODO: Can we improve the API? have `reverse_iter` return an optional?
-  reverse_iter ([&resolved_definition, &name] (Node &current) {
+  reverse_iter (start, [&resolved_definition, &name] (Node &current) {
     auto candidate = current.rib.get (name.as_string ());
 
     return candidate.map_or (
@@ -318,6 +318,13 @@ ForeverStack<N>::get (const Identifier &name)
   return resolved_definition;
 }
 
+template <Namespace N>
+tl::optional<Rib::Definition>
+ForeverStack<N>::get (const Identifier &name)
+{
+  return get (cursor (), name);
+}
+
 template <Namespace N>
 tl::optional<Rib::Definition>
 ForeverStack<N>::get_lang_prelude (const Identifier &name)
@@ -625,23 +632,25 @@ template <Namespace N>
 template <typename S>
 tl::optional<Rib::Definition>
 ForeverStack<N>::resolve_path (
-  const std::vector<S> &segments, bool has_opening_scope_resolution,
+  const std::vector<S> &segments, ResolutionMode mode,
   std::function<void (const S &, NodeId)> insert_segment_resolution,
   std::vector<Error> &collect_errors)
 {
   rust_assert (!segments.empty ());
 
-  // handle paths with opening scopes
-  std::function<void (void)> cleanup_current = [] () {};
-  if (has_opening_scope_resolution)
+  std::reference_wrapper<Node> starting_point = cursor ();
+  switch (mode)
     {
-      Node *last_current = &cursor_reference.get ();
-      if (get_rust_edition () == Edition::E2015)
-	cursor_reference = root;
-      else
-	cursor_reference = extern_prelude;
-      cleanup_current
-	= [this, last_current] () { cursor_reference = *last_current; };
+    case ResolutionMode::Normal:
+      break; // default
+    case ResolutionMode::FromRoot:
+      starting_point = root;
+      break;
+    case ResolutionMode::FromExtern:
+      starting_point = extern_prelude;
+      break;
+    default:
+      rust_unreachable ();
     }
 
   // if there's only one segment, we just use `get`
@@ -654,59 +663,53 @@ ForeverStack<N>::resolve_path (
 	    lang_item.value ());
 
 	  insert_segment_resolution (seg, seg_id);
-	  cleanup_current ();
 	  // TODO: does NonShadowable matter?
 	  return Rib::Definition::NonShadowable (seg_id);
 	}
 
       tl::optional<Rib::Definition> res
-	= get (unwrap_type_segment (segments.back ()).as_string ());
+	= get (starting_point.get (),
+	       unwrap_type_segment (segments.back ()).as_string ());
 
       if (!res)
 	res = get_lang_prelude (
 	  unwrap_type_segment (segments.back ()).as_string ());
 
       if (res && !res->is_ambiguous ())
 	insert_segment_resolution (segments.back (), res->get_node_id ());
-      cleanup_current ();
       return res;
     }
 
-  std::reference_wrapper<Node> starting_point = cursor ();
+  return find_starting_point (segments, starting_point,
+			      insert_segment_resolution, collect_errors)
+    .and_then (
+      [this, &segments, &starting_point, &insert_segment_resolution,
+       &collect_errors] (typename std::vector<S>::const_iterator iterator) {
+	return resolve_segments (starting_point.get (), segments, iterator,
+				 insert_segment_resolution, collect_errors);
+      })
+    .and_then ([this, &segments, &insert_segment_resolution] (
+		 Node &final_node) -> tl::optional<Rib::Definition> {
+      // leave resolution within impl blocks to type checker
+      if (final_node.rib.kind == Rib::Kind::TraitOrImpl)
+	return tl::nullopt;
+
+      auto &seg = unwrap_type_segment (segments.back ());
+      std::string seg_name = seg.as_string ();
+
+      // assuming this can't be a lang item segment
+      tl::optional<Rib::Definition> res
+	= resolve_final_segment (final_node, seg_name,
+				 seg.is_lower_self_seg ());
+      // Ok we didn't find it in the rib, Lets try the prelude...
+      if (!res)
+	res = get_lang_prelude (seg_name);
 
-  auto res
-    = find_starting_point (segments, starting_point, insert_segment_resolution,
-			   collect_errors)
-	.and_then (
-	  [this, &segments, &starting_point, &insert_segment_resolution,
-	   &collect_errors] (typename std::vector<S>::const_iterator iterator) {
-	    return resolve_segments (starting_point.get (), segments, iterator,
-				     insert_segment_resolution, collect_errors);
-	  })
-	.and_then ([this, &segments, &insert_segment_resolution] (
-		     Node &final_node) -> tl::optional<Rib::Definition> {
-	  // leave resolution within impl blocks to type checker
-	  if (final_node.rib.kind == Rib::Kind::TraitOrImpl)
-	    return tl::nullopt;
-
-	  auto &seg = unwrap_type_segment (segments.back ());
-	  std::string seg_name = seg.as_string ();
-
-	  // assuming this can't be a lang item segment
-	  tl::optional<Rib::Definition> res
-	    = resolve_final_segment (final_node, seg_name,
-				     seg.is_lower_self_seg ());
-	  // Ok we didn't find it in the rib, Lets try the prelude...
-	  if (!res)
-	    res = get_lang_prelude (seg_name);
-
-	  if (res && !res->is_ambiguous ())
-	    insert_segment_resolution (segments.back (), res->get_node_id ());
-
-	  return res;
-	});
-  cleanup_current ();
-  return res;
+      if (res && !res->is_ambiguous ())
+	insert_segment_resolution (segments.back (), res->get_node_id ());
+
+      return res;
+    });
 }
 
 template <Namespace N>

gcc/rust/resolve/rust-late-name-resolver-2.0.cc

@@ -520,6 +520,62 @@ Late::visit (AST::TypePath &type)
 		 Definition (resolved->get_node_id ()));
 }
 
+void
+Late::visit (AST::Visibility &vis)
+{
+  if (!vis.has_path ())
+    return;
+
+  AST::SimplePath &path = vis.get_path ();
+
+  rust_assert (path.get_segments ().size ());
+  auto &first_seg = path.get_segments ()[0];
+
+  auto mode = ResolutionMode::Normal;
+
+  if (path.has_opening_scope_resolution ())
+    {
+      if (get_rust_edition () == Edition::E2015)
+	mode = ResolutionMode::FromRoot;
+      else
+	mode = ResolutionMode::FromExtern;
+    }
+  else if (!first_seg.is_crate_path_seg () && !first_seg.is_super_path_seg ()
+	   && !first_seg.is_lower_self_seg ())
+    {
+      if (get_rust_edition () == Edition::E2015)
+	{
+	  mode = ResolutionMode::FromRoot;
+	}
+      else
+	{
+	  rust_error_at (path.get_locus (),
+			 "relative paths are not supported in visibilities in "
+			 "2018 edition or later");
+	  return;
+	}
+    }
+
+  auto res = ctx.resolve_path (path.get_segments (), mode, Namespace::Types);
+
+  if (!res.has_value ())
+    {
+      rust_error_at (path.get_locus (), ErrorCode::E0433,
+		     "could not resolve path %qs", path.as_string ().c_str ());
+      return;
+    }
+
+  // TODO: is this possible?
+  if (res->is_ambiguous ())
+    {
+      rust_error_at (path.get_locus (), ErrorCode::E0659, "%qs is ambiguous",
+		     path.as_string ().c_str ());
+      return;
+    }
+
+  ctx.map_usage (Usage (path.get_node_id ()), Definition (res->get_node_id ()));
+}
+
 void
 Late::visit (AST::Trait &trait)
 {

gcc/rust/resolve/rust-late-name-resolver-2.0.h

@@ -60,6 +60,7 @@ class Late : public DefaultResolver
   void visit (AST::LoopLabel &) override;
   void visit (AST::PathInExpression &) override;
   void visit (AST::TypePath &) override;
+  void visit (AST::Visibility &) override;
   void visit (AST::Trait &) override;
   void visit (AST::StructExprStruct &) override;
   void visit (AST::StructExprStructBase &) override;