Add early resolver error collection

We need to collect the early resolver's macros error to emit them at a
later stage after further expansion in order to retrieve macros defined
by other macro invocations.

gcc/rust/ChangeLog:

	* resolve/rust-early-name-resolver-2.0.cc (Early::visit):
	Collect error instead of emitting it.
	* resolve/rust-early-name-resolver-2.0.h (std::function<void):
	Add type definition for collection.
	* rust-session-manager.cc (Session::expansion): Collect errors
	while fixed point is not reached then emit remaining errors.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

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

@@ -135,8 +135,10 @@ Early::visit (AST::MacroInvocation &invoc)
   // if the definition still does not have a value, then it's an error
   if (!definition.has_value ())
     {
-      rust_error_at (invoc.get_locus (), ErrorCode::E0433,
-		     "could not resolve macro invocation");
+      collect_error ([&] () {
+	rust_error_at (invoc.get_locus (), ErrorCode::E0433,
+		       "could not resolve macro invocation");
+      });
       return;
     }
 

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

@@ -28,6 +28,8 @@
 namespace Rust {
 namespace Resolver2_0 {
 
+using ResolveError = std::function<void ()>;
+
 class Early : public DefaultResolver
 {
   using DefaultResolver::visit;
@@ -37,6 +39,11 @@ class Early : public DefaultResolver
 
   void go (AST::Crate &crate);
 
+  const std::vector<ResolveError> &get_macro_resolve_errors () const
+  {
+    return macro_resolve_errors;
+  }
+
   // we need to handle definitions for textual scoping
   void visit (AST::MacroRulesDefinition &) override;
 
@@ -76,6 +83,9 @@ class Early : public DefaultResolver
   };
 
   TextualScope textual_scope;
+  std::vector<ResolveError> macro_resolve_errors;
+
+  void collect_error (ResolveError e) { macro_resolve_errors.push_back (e); }
 };
 
 } // namespace Resolver2_0

gcc/rust/rust-session-manager.cc

@@ -875,6 +875,7 @@ Session::expansion (AST::Crate &crate)
   /* expand by calling cxtctxt object's monotonic_expander's expand_crate
    * method. */
   MacroExpander expander (crate, cfg, *this);
+  std::vector<Resolver2_0::ResolveError> macro_errors;
 
   while (!fixed_point_reached && iterations < cfg.recursion_limit)
     {
@@ -883,7 +884,11 @@ Session::expansion (AST::Crate &crate)
       auto ctx = Resolver2_0::NameResolutionContext ();
 
       if (flag_name_resolution_2_0)
-	Resolver2_0::Early (ctx).go (crate);
+	{
+	  Resolver2_0::Early early (ctx);
+	  early.go (crate);
+	  macro_errors = early.get_macro_resolve_errors ();
+	}
       else
 	Resolver::EarlyNameResolver ().go (crate);
 
@@ -897,6 +902,11 @@ Session::expansion (AST::Crate &crate)
 	break;
     }
 
+  for (auto &error : macro_errors)
+    {
+      error ();
+    }
+
   if (iterations == cfg.recursion_limit)
     {
       auto last_invoc = expander.get_last_invocation ();