blink_gc_plugin: detect singletons with embedded ScriptWrappables.

tools/clang/blink_gc_plugin/BlinkGCPluginConsumer.cpp

Index: tools/clang/blink_gc_plugin/BlinkGCPluginConsumer.cpp
diff --git a/tools/clang/blink_gc_plugin/BlinkGCPluginConsumer.cpp b/tools/clang/blink_gc_plugin/BlinkGCPluginConsumer.cpp
index 28af4bc098c5aa62af72bed93d51b7b8f0cb722c..ff05e0712001ed921b54f09b9c1e63f2408cbfb7 100644
--- a/tools/clang/blink_gc_plugin/BlinkGCPluginConsumer.cpp
+++ b/tools/clang/blink_gc_plugin/BlinkGCPluginConsumer.cpp
@@ -11,6 +11,7 @@
 #include "CheckFieldsVisitor.h"
 #include "CheckFinalizerVisitor.h"
 #include "CheckGCRootsVisitor.h"
+#include "CheckSingletonVisitor.h"
 #include "CheckTraceVisitor.h"
 #include "CollectVisitor.h"
 #include "JsonWriter.h"
@@ -87,7 +88,7 @@ void BlinkGCPluginConsumer::HandleTranslationUnit(ASTContext& context) {
 
   ParseFunctionTemplates(context.getTranslationUnitDecl());
 
-  CollectVisitor visitor;
+  CollectVisitor visitor(options_.warn_singleton_with_scriptwrappables);
   visitor.TraverseDecl(context.getTranslationUnitDecl());
 
   if (options_.dump_graph) {
@@ -120,6 +121,9 @@ void BlinkGCPluginConsumer::HandleTranslationUnit(ASTContext& context) {
   for (const auto& method : visitor.trace_decls())
     CheckTracingMethod(method);
 
+  for (const auto& singleton : visitor.singleton_decls())
+    CheckStaticSingleton(singleton);
+
   if (json_) {
     json_->CloseList();
     delete json_;
@@ -564,6 +568,37 @@ void BlinkGCPluginConsumer::CheckTraceMethod(
   }
 }
 
+void BlinkGCPluginConsumer::CheckStaticSingleton(clang::VarDecl* singleton) {
+  // Ignorance is a declaration-level annotation, so eagerly checked for
+  // before adding it to the processing set.
+  assert(!Config::IsIgnoreAnnotated(singleton));
+
+  const Type* singleton_type = singleton->getType().getTypePtr();
+  if (singleton_type->isPointerType() || singleton_type->isReferenceType())
+    singleton_type = singleton_type->getPointeeType().getTypePtr();
+
+  CXXRecordDecl* record = singleton_type->getAsCXXRecordDecl();
+  if (!record)
+    return;
+
+  RecordInfo* info = cache_.Lookup(record);
+  if (!info)
+    return;
+
+  // Walk over singleton type, looking for undesirable ScriptWrappable
+  // references.
+  CheckSingletonVisitor visitor;
+  if (!visitor.CheckIfSafe(info, singleton_type)) {
+    reporter_.StaticSingletonContainsScriptWrappable(singleton);
+    for (const auto& error : visitor.illegal_types()) {
+      reporter_.NoteUnsafeScriptWrappableField(
+          singleton, error.first,
+          QualType::getAsString(
+              error.second->getCanonicalTypeInternal().split()));
+    }
+  }
+}
+
 void BlinkGCPluginConsumer::DumpClass(RecordInfo* info) {
   if (!json_)
     return;