Revert of GC plugin: improve error reporting when tracing illegal fields.

tools/clang/blink_gc_plugin/Edge.h

 // 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.
 
 #ifndef TOOLS_BLINK_GC_PLUGIN_EDGE_H_
 #define TOOLS_BLINK_GC_PLUGIN_EDGE_H_
 
 #include <cassert>
 #include <deque>
 #include <vector>
 
 #include "TracingStatus.h"
 
 class RecordInfo;
 
 class Edge;
-class Collection;
-class CrossThreadPersistent;
-class Member;
-class OwnPtr;
-class Persistent;
+class Value;
 class RawPtr;
 class RefPtr;
-class UniquePtr;
-class Value;
+class OwnPtr;
+class Member;
 class WeakMember;
+class Persistent;
+class Collection;
 
 // Bare-bones visitor.
 class EdgeVisitor {
  public:
   virtual ~EdgeVisitor() {}
   virtual void VisitValue(Value*) {}
   virtual void VisitRawPtr(RawPtr*) {}
   virtual void VisitRefPtr(RefPtr*) {}
   virtual void VisitOwnPtr(OwnPtr*) {}
-  virtual void VisitUniquePtr(UniquePtr*) {}
   virtual void VisitMember(Member*) {}
   virtual void VisitWeakMember(WeakMember*) {}
   virtual void VisitPersistent(Persistent*) {}
-  virtual void VisitCrossThreadPersistent(CrossThreadPersistent*) {}
   virtual void VisitCollection(Collection*) {}
 };
 
 // Recursive edge visitor. The traversed path is accessible in context.
 class RecursiveEdgeVisitor : public EdgeVisitor {
  public:
   // Overrides that recursively walk the edges and record the path.
   void VisitValue(Value*) override;
   void VisitRawPtr(RawPtr*) override;
   void VisitRefPtr(RefPtr*) override;
   void VisitOwnPtr(OwnPtr*) override;
-  void VisitUniquePtr(UniquePtr*) override;
   void VisitMember(Member*) override;
   void VisitWeakMember(WeakMember*) override;
   void VisitPersistent(Persistent*) override;
-  void VisitCrossThreadPersistent(CrossThreadPersistent*) override;
   void VisitCollection(Collection*) override;
 
  protected:
   typedef std::deque<Edge*> Context;
   Context& context() { return context_; }
   Edge* Parent() { return context_.empty() ? 0 : context_.front(); }
   void Enter(Edge* e) { return context_.push_front(e); }
   void Leave() { context_.pop_front(); }
 
   // Default callback to overwrite in visitor subclass.
   virtual void AtValue(Value*);
   virtual void AtRawPtr(RawPtr*);
   virtual void AtRefPtr(RefPtr*);
   virtual void AtOwnPtr(OwnPtr*);
-  virtual void AtUniquePtr(UniquePtr*);
   virtual void AtMember(Member*);
   virtual void AtWeakMember(WeakMember*);
   virtual void AtPersistent(Persistent*);
-  virtual void AtCrossThreadPersistent(CrossThreadPersistent*);
   virtual void AtCollection(Collection*);
 
  private:
   Context context_;
 };
 
 // Base class for all edges.
 class Edge {
  public:
   enum NeedsTracingOption { kRecursive, kNonRecursive };
   enum LivenessKind { kWeak, kStrong, kRoot };
 
   virtual ~Edge() {}
   virtual LivenessKind Kind() = 0;
   virtual void Accept(EdgeVisitor*) = 0;
   virtual bool NeedsFinalization() = 0;
   virtual TracingStatus NeedsTracing(NeedsTracingOption) {
     return TracingStatus::Unknown();
   }
 
   virtual bool IsValue() { return false; }
   virtual bool IsRawPtr() { return false; }
   virtual bool IsRefPtr() { return false; }
   virtual bool IsOwnPtr() { return false; }
-  virtual bool IsUniquePtr() { return false; }
   virtual bool IsMember() { return false; }
   virtual bool IsWeakMember() { return false; }
+  virtual bool IsPersistent() { return false; }
   virtual bool IsCollection() { return false; }
 };
 
 // A value edge is a direct edge to some type, eg, part-object edges.
 class Value : public Edge {
  public:
   explicit Value(RecordInfo* value) : value_(value) {};
   bool IsValue() override { return true; }
   LivenessKind Kind() override { return kStrong; }
   bool NeedsFinalization() override;
@@ skipping 23 matching lines @@
   RawPtr(Edge* ptr, bool is_ref_type)
       : PtrEdge(ptr)
       , is_ref_type_(is_ref_type)
   {
   }
 
   bool IsRawPtr() { return true; }
   LivenessKind Kind() { return kWeak; }
   bool NeedsFinalization() { return false; }
   TracingStatus NeedsTracing(NeedsTracingOption) {
-    return TracingStatus::Illegal();
+    return TracingStatus::Unneeded();
   }
   void Accept(EdgeVisitor* visitor) { visitor->VisitRawPtr(this); }
 
   bool HasReferenceType() { return is_ref_type_; }
  private:
   bool is_ref_type_;
 };
 
 class RefPtr : public PtrEdge {
  public:
   explicit RefPtr(Edge* ptr) : PtrEdge(ptr) { }
   bool IsRefPtr() { return true; }
   LivenessKind Kind() { return kStrong; }
   bool NeedsFinalization() { return true; }
   TracingStatus NeedsTracing(NeedsTracingOption) {
-    return TracingStatus::Illegal();
+    return TracingStatus::Unneeded();
   }
   void Accept(EdgeVisitor* visitor) { visitor->VisitRefPtr(this); }
 };
 
 class OwnPtr : public PtrEdge {
  public:
   explicit OwnPtr(Edge* ptr) : PtrEdge(ptr) { }
   bool IsOwnPtr() { return true; }
   LivenessKind Kind() { return kStrong; }
   bool NeedsFinalization() { return true; }
   TracingStatus NeedsTracing(NeedsTracingOption) {
-    return TracingStatus::Illegal();
+    return TracingStatus::Unneeded();
   }
   void Accept(EdgeVisitor* visitor) { visitor->VisitOwnPtr(this); }
 };
 
-class UniquePtr : public PtrEdge {
- public:
-  explicit UniquePtr(Edge* ptr) : PtrEdge(ptr) { }
-  bool IsUniquePtr() { return true; }
-  LivenessKind Kind() { return kStrong; }
-  bool NeedsFinalization() { return true; }
-  TracingStatus NeedsTracing(NeedsTracingOption) {
-    return TracingStatus::Illegal();
-  }
-  void Accept(EdgeVisitor* visitor) { visitor->VisitUniquePtr(this); }
-};
-
 class Member : public PtrEdge {
  public:
   explicit Member(Edge* ptr) : PtrEdge(ptr) { }
   bool IsMember() { return true; }
   LivenessKind Kind() { return kStrong; }
   bool NeedsFinalization() { return false; }
   TracingStatus NeedsTracing(NeedsTracingOption) {
     return TracingStatus::Needed();
   }
   void Accept(EdgeVisitor* visitor) { visitor->VisitMember(this); }
 };
 
 class WeakMember : public PtrEdge {
  public:
   explicit WeakMember(Edge* ptr) : PtrEdge(ptr) { }
   bool IsWeakMember() { return true; }
   LivenessKind Kind() { return kWeak; }
   bool NeedsFinalization() { return false; }
   TracingStatus NeedsTracing(NeedsTracingOption) {
     return TracingStatus::Needed();
   }
   void Accept(EdgeVisitor* visitor) { visitor->VisitWeakMember(this); }
 };
 
 class Persistent : public PtrEdge {
  public:
   explicit Persistent(Edge* ptr) : PtrEdge(ptr) { }
+  bool IsPersistent() { return true; }
   LivenessKind Kind() { return kRoot; }
   bool NeedsFinalization() { return true; }
   TracingStatus NeedsTracing(NeedsTracingOption) {
     return TracingStatus::Unneeded();
   }
   void Accept(EdgeVisitor* visitor) { visitor->VisitPersistent(this); }
 };
 
-class CrossThreadPersistent : public PtrEdge {
- public:
-  explicit CrossThreadPersistent(Edge* ptr) : PtrEdge(ptr) { }
-  LivenessKind Kind() { return kRoot; }
-  bool NeedsFinalization() { return true; }
-  TracingStatus NeedsTracing(NeedsTracingOption) {
-    return TracingStatus::Illegal();
-  }
-  void Accept(EdgeVisitor* visitor) {
-    visitor->VisitCrossThreadPersistent(this);
-  }
-};
-
 class Collection : public Edge {
  public:
   typedef std::vector<Edge*> Members;
   Collection(RecordInfo* info, bool on_heap, bool is_root)
       : info_(info),
         on_heap_(on_heap),
         is_root_(is_root) {}
   ~Collection() {
     for (Members::iterator it = members_.begin(); it != members_.end(); ++it) {
       assert(*it && "Collection-edge members must be non-null");
@@ skipping 26 matching lines @@
   }
 
  private:
   RecordInfo* info_;
   Members members_;
   bool on_heap_;
   bool is_root_;
 };
 
 #endif  // TOOLS_BLINK_GC_PLUGIN_EDGE_H_