blink_gc_plugin: detect singletons with embedded ScriptWrappables.

tools/clang/blink_gc_plugin/CheckSingletonVisitor.cpp

Index: tools/clang/blink_gc_plugin/CheckSingletonVisitor.cpp
diff --git a/tools/clang/blink_gc_plugin/CheckSingletonVisitor.cpp b/tools/clang/blink_gc_plugin/CheckSingletonVisitor.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..c3bc43e615a0ec3884a30c3a35886167565cabcd
--- /dev/null
+++ b/tools/clang/blink_gc_plugin/CheckSingletonVisitor.cpp
@@ -0,0 +1,150 @@
+// Copyright 2017 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.
+
+#include "CheckSingletonVisitor.h"
+
+#include "BlinkGCPluginOptions.h"
+#include "Config.h"
+#include "RecordInfo.h"
+
+using namespace clang;
+
+CheckSingletonVisitor::CheckSingletonVisitor() = default;
+
+CheckSingletonVisitor::~CheckSingletonVisitor() = default;
+
+bool CheckSingletonVisitor::IsScriptWrappable(RecordInfo* info) {
+  return Config::IsScriptWrappable(info->name()) && info->IsInBlinkNamespace();
+}
+
+bool CheckSingletonVisitor::InheritsScriptWrappable(CXXRecordDecl* record) {
+  RecordInfo* info = info_->cache()->Lookup(record);
+  if (!info)
+    return false;
+
+  if (IsScriptWrappable(info))
+    return true;
+
+  for (auto& base : info->GetBases())
+    if (InheritsScriptWrappable(base.first))
+      return true;
+
+  return false;
+}
+
+void CheckSingletonVisitor::CheckScriptWrappable(const std::string& name,
+                                                 const Type* type) {
+  RecordInfo* info = info_->cache()->Lookup(type);
+  if (!info)
+    return;
+
+  if (IsScriptWrappable(info)) {
+    std::string context = GenerateErrorContext(name);
+    illegal_types_.push_back(std::make_pair(context, type));
+    return;
+  }
+
+  RecordInfo::TemplateArgs args;
+  if (Config::IsMember(info->name()) && info->GetTemplateArgs(1, &args)) {
+    PushType(name, args[0]);
+    return;
+  }
+  if (Config::IsWeakMember(info->name()) && info->GetTemplateArgs(1, &args)) {
+    PushType(name, args[0]);
+    return;
+  }
+  bool has_persistent_name = false;
+  if (const Type* arg_type =
+          info->GetPersistentArgumentType(has_persistent_name)) {
+    PushType(name, arg_type);
+    return;
+  }
+  if (Config::IsGCCollection(info->name()) ||
+      Config::IsWTFCollection(info->name())) {
+    if (Config::IsPersistentGCCollection(info->name()) ||
+        info->IsHeapAllocatedCollection()) {
+      size_t count = Config::CollectionDimension(info->name());
+      if (info->GetTemplateArgs(count, &args)) {
+        for (const auto& t : args)
+          PushType(name, t);
+        return;
+      }
+    }
+  }
+
+  // First check if the class inherits |blink::ScriptWrappable|,
+  // and fail early if so.
+  if (InheritsScriptWrappable(info->record())) {
+    std::string context = GenerateErrorContext(name);
+    illegal_types_.push_back(std::make_pair(context, type));
+    return;
+  }
+  for (auto& base : info->GetBases()) {
+    PushType(name, base.first->getTypeForDecl());
+  }
+  for (auto& field : info->GetFields()) {
+    CheckScriptWrappable(field.first->getNameAsString(),
+                         field.first->getType().getTypePtr());
+  }
+}
+
+void CheckSingletonVisitor::PushType(const Type* type) {
+  if (type->isPointerType() || type->isReferenceType())
+    return;
+
+  if (already_seen_.find(type) != already_seen_.end())
+    return;
+
+  already_seen_.insert(type);
+  types_stack_.push_back(std::make_pair("", type));
+}
+
+void CheckSingletonVisitor::PushType(const std::string& name,
+                                     const Type* type) {
+  if (type->isPointerType() || type->isReferenceType())
+    return;
+
+  if (already_seen_.find(type) != already_seen_.end())
+    return;
+
+  already_seen_.insert(type);
+  types_stack_.push_back(std::make_pair(name, type));
+}
+
+bool CheckSingletonVisitor::CheckIfSafe(RecordInfo* info, const Type* type) {
+  info_ = info;
+  types_stack_.push_back(std::make_pair("", type));
+  while (types_stack_.size()) {
+    auto t = types_stack_.back();
+    types_stack_.pop_back();
+    if (!t.second) {
+      // We push a stack marker when extending the
+      // (field) error context - pop the context when
+      // it is encountered again.
+      error_context_.pop_back();
+      continue;
+    } else if (!t.first.empty()) {
+      error_context_.push_back(t.first);
+      types_stack_.push_back(std::make_pair(t.first, nullptr));
+    }
+    CheckScriptWrappable("", t.second);
+  }
+  return !illegal_types_.size();
+}
+
+std::string CheckSingletonVisitor::GenerateErrorContext(
+    const std::string& name) {
+  std::string result;
+  for (const auto& elem : error_context_) {
+    if (!result.empty())
+      result.append(" => ");
+    result.append(elem);
+  }
+  if (!name.empty()) {
+    if (!result.empty())
+      result.append(" => ");
+    result.append(name);
+  }
+  return result;
+}