early-name-resolver: Add simple macro name resolution

This name resolver performs the same macro name resolution as what was
previously done by the AttrVisitor visitor and macro expander.

It also resolves macro expressions in builtin-macros properly, as well
as expanded AST nodes when necessary.

gcc/rust/Make-lang.in

@@ -94,6 +94,7 @@ GRS_OBJS = \
     rust/rust-ast-lower-base.o \
     rust/rust-ast-lower-pattern.o \
     rust/rust-ast-lower-item.o \
+    rust/rust-early-name-resolver.o \
     rust/rust-name-resolver.o \
     rust/rust-ast-resolve.o \
     rust/rust-ast-resolve-base.o \

gcc/rust/expand/rust-attribute-visitor.cc

@@ -2877,16 +2877,6 @@ AttrVisitor::visit (AST::MacroRulesDefinition &rules_def)
       rules_def.mark_for_strip ();
       return;
     }
-
-  // I don't think any macro rules can be stripped in any way
-
-  auto path = Resolver::CanonicalPath::new_seg (rules_def.get_node_id (),
-						rules_def.get_rule_name ());
-  expander.resolver->get_macro_scope ().insert (path, rules_def.get_node_id (),
-						rules_def.get_locus ());
-  expander.mappings->insert_macro_def (&rules_def);
-  rust_debug_loc (rules_def.get_locus (), "inserting macro def: [%s]",
-		  path.get ().c_str ());
 }
 
 void

gcc/rust/expand/rust-macro-builtins.cc

@@ -24,6 +24,7 @@
 #include "rust-macro-invoc-lexer.h"
 #include "rust-lex.h"
 #include "rust-parse.h"
+#include "rust-early-name-resolver.h"
 #include "rust-attribute-visitor.h"
 
 namespace Rust {
@@ -70,9 +71,11 @@ try_expand_macro_expression (AST::Expr *expr, MacroExpander *expander)
 {
   rust_assert (expander);
 
-  auto vis = Rust::AttrVisitor (*expander);
-  expr->accept_vis (vis);
-  return expander->take_expanded_fragment (vis);
+  auto attr_visitor = Rust::AttrVisitor (*expander);
+  auto early_name_resolver = Resolver::EarlyNameResolver ();
+  expr->accept_vis (early_name_resolver);
+  expr->accept_vis (attr_visitor);
+  return expander->take_expanded_fragment (attr_visitor);
 }
 
 /* Expand and then extract a string literal from the macro */

gcc/rust/expand/rust-macro-expand.cc

@@ -23,6 +23,7 @@
 #include "rust-diagnostics.h"
 #include "rust-parse.h"
 #include "rust-attribute-visitor.h"
+#include "rust-early-name-resolver.h"
 
 namespace Rust {
 AST::ASTFragment
@@ -138,32 +139,17 @@ MacroExpander::expand_invoc (AST::MacroInvocation &invoc, bool has_semicolon)
   //      - else is unreachable
   //  - derive container macro - unreachable
 
-  // lookup the rules for this macro
-  NodeId resolved_node = UNKNOWN_NODEID;
-  NodeId source_node = UNKNOWN_NODEID;
-  if (has_semicolon)
-    source_node = invoc.get_macro_node_id ();
-  else
-    source_node = invoc.get_pattern_node_id ();
-  auto seg
-    = Resolver::CanonicalPath::new_seg (source_node,
-					invoc_data.get_path ().as_string ());
-
-  bool found = resolver->get_macro_scope ().lookup (seg, &resolved_node);
-  if (!found)
-    {
-      rust_error_at (invoc.get_locus (), "unknown macro: [%s]",
-		     seg.get ().c_str ());
-      return;
-    }
+  auto fragment = AST::ASTFragment::create_error ();
+  invoc_data.set_expander (this);
 
   // lookup the rules
   AST::MacroRulesDefinition *rules_def = nullptr;
-  bool ok = mappings->lookup_macro_def (resolved_node, &rules_def);
-  rust_assert (ok);
+  bool ok = mappings->lookup_macro_invocation (invoc, &rules_def);
 
-  auto fragment = AST::ASTFragment::create_error ();
-  invoc_data.set_expander (this);
+  // If there's no rule associated with the invocation, we can simply return
+  // early. The early name resolver will have already emitted an error.
+  if (!ok)
+    return;
 
   if (rules_def->is_builtin ())
     fragment

gcc/rust/expand/rust-macro-expand.h

@@ -25,6 +25,7 @@
 #include "rust-ast.h"
 #include "rust-macro.h"
 #include "rust-hir-map.h"
+#include "rust-early-name-resolver.h"
 #include "rust-name-resolver.h"
 #include "rust-macro-invoc-lexer.h"
 
@@ -323,10 +324,13 @@ struct MacroExpander
     AST::ASTFragment old_fragment = std::move (expanded_fragment);
     auto accumulator = std::vector<AST::SingleASTNode> ();
     expanded_fragment = AST::ASTFragment::create_error ();
+    auto early_name_resolver = Resolver::EarlyNameResolver ();
 
     for (auto &node : old_fragment.get_nodes ())
       {
 	expansion_depth++;
+
+	node.accept_vis (early_name_resolver);
 	node.accept_vis (vis);
 	// we'll decide the next move according to the outcome of the macro
 	// expansion