Blink GC plugin: require that trace call base::trace and traceAfterDispatch call base::traceAfterDi…

tools/clang/blink_gc_plugin/BlinkGCPlugin.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This clang plugin checks various invariants of the Blink garbage
 // collection infrastructure.
 //
 // Errors are described at:
 // http://www.chromium.org/developers/blink-gc-plugin-errors
 
@@ skipping 338 matching lines @@
               if (callback->hasBody()) {
                 CheckTraceVisitor nested_visitor(info_);
                 nested_visitor.TraverseStmt(callback->getBody());
               }
             }
           }
         }
         return true;
       }
 
-      // TODO: It is possible to have multiple bases, where one must be traced
-      // using a traceAfterDispatch. In such a case we should also check that
-      // the mixin does not add a vtable.
-      if (Config::IsTraceMethod(fn) && member->hasQualifier()) {
+      // Currently, a manually dispatched class cannot have mixin bases (having
+      // one would add a vtable which we explicitly check against). This means
+      // that we can only make calls to a trace method of the same name. Revisit
+      // this if our mixin/vtable assumption changes.
+      if (Config::IsTraceMethod(fn) &&
+          fn->getName() == trace_->getName() &&
+          member->hasQualifier()) {
         if (const Type* type = member->getQualifier()->getAsType()) {
           if (CXXRecordDecl* decl = type->getAsCXXRecordDecl()) {
             RecordInfo::Bases::iterator it = info_->GetBases().find(decl);
             if (it != info_->GetBases().end())
               it->second.MarkTraced();
           }
         }
       }
     }
     return true;
@@ skipping 1056 matching lines @@
 
  private:
   BlinkGCPluginOptions options_;
 };
 
 }  // namespace
 
 static FrontendPluginRegistry::Add<BlinkGCPluginAction> X(
     "blink-gc-plugin",
     "Check Blink GC invariants");