gccrs: Small improvements to DefaultASTVisitor and nr2.0

gcc/rust/ChangeLog:

	* ast/rust-ast-visitor.cc
	(DefaultASTVisitor::visit): Only visit the path of an instance
	of Visibility if the instance has a path.
	* ast/rust-ast.h
	(SimplePath::SimplePath): Make sure constructors are explicit.
	* resolve/rust-early-name-resolver-2.0.cc
	(Early::visit_attributes): Pass entire paths to
	NameResolutionContext::resolve_path.
	(Early::visit): Likewise and avoid copying a path.
	* resolve/rust-forever-stack.hxx
	(ForeverStack::resolve_path): Assert that at least one path
	segment has been passed in.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>

gcc/rust/ast/rust-ast-visitor.cc

@@ -762,7 +762,8 @@ DefaultASTVisitor::visit (AST::TypeBoundWhereClauseItem &item)
 void
 DefaultASTVisitor::visit (AST::Visibility &vis)
 {
-  visit (vis.get_path ());
+  if (vis.has_path ())
+    visit (vis.get_path ());
 }
 
 void

gcc/rust/ast/rust-ast.h

@@ -402,15 +402,15 @@ class SimplePath
 
 public:
   // Constructor
-  SimplePath (std::vector<SimplePathSegment> path_segments,
-	      bool has_opening_scope_resolution = false,
-	      location_t locus = UNDEF_LOCATION)
+  explicit SimplePath (std::vector<SimplePathSegment> path_segments,
+		       bool has_opening_scope_resolution = false,
+		       location_t locus = UNDEF_LOCATION)
     : opening_scope_resolution (has_opening_scope_resolution),
       segments (std::move (path_segments)), locus (locus),
       node_id (Analysis::Mappings::get ().get_next_node_id ())
   {}
 
-  SimplePath (Identifier ident)
+  explicit SimplePath (Identifier ident)
     : opening_scope_resolution (false),
       segments ({SimplePathSegment (ident.as_string (), ident.get_locus ())}),
       locus (ident.get_locus ()),

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

@@ -249,7 +249,7 @@ Early::visit (AST::Module &module)
 void
 Early::visit (AST::MacroInvocation &invoc)
 {
-  auto path = invoc.get_invoc_data ().get_path ();
+  auto &path = invoc.get_invoc_data ().get_path ();
 
   if (invoc.get_kind () == AST::MacroInvocation::InvocKind::Builtin)
     for (auto &pending_invoc : invoc.get_pending_eager_invocations ())
@@ -272,7 +272,7 @@ Early::visit (AST::MacroInvocation &invoc)
   // we won't have changed `definition` from `nullopt` if there are more
   // than one segments in our path
   if (!definition.has_value ())
-    definition = ctx.resolve_path (path.get_segments (), Namespace::Macros);
+    definition = ctx.resolve_path (path, Namespace::Macros);
 
   // if the definition still does not have a value, then it's an error
   if (!definition.has_value ())
@@ -314,8 +314,8 @@ Early::visit_attributes (std::vector<AST::Attribute> &attrs)
 	  auto traits = attr.get_traits_to_derive ();
 	  for (auto &trait : traits)
 	    {
-	      auto definition = ctx.resolve_path (trait.get ().get_segments (),
-						  Namespace::Macros);
+	      auto definition
+		= ctx.resolve_path (trait.get (), Namespace::Macros);
 	      if (!definition.has_value ())
 		{
 		  // FIXME: Change to proper error message
@@ -337,8 +337,8 @@ Early::visit_attributes (std::vector<AST::Attribute> &attrs)
 		 ->lookup_builtin (name)
 		 .is_error ()) // Do not resolve builtins
 	{
-	  auto definition = ctx.resolve_path (attr.get_path ().get_segments (),
-					      Namespace::Macros);
+	  auto definition
+	    = ctx.resolve_path (attr.get_path (), Namespace::Macros);
 	  if (!definition.has_value ())
 	    {
 	      // FIXME: Change to proper error message

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

@@ -629,7 +629,7 @@ ForeverStack<N>::resolve_path (
   std::function<void (const S &, NodeId)> insert_segment_resolution,
   std::vector<Error> &collect_errors)
 {
-  // TODO: What to do if segments.empty() ?
+  rust_assert (!segments.empty ());
 
   // handle paths with opening scopes
   std::function<void (void)> cleanup_current = [] () {};