Explicitly mask enum values to work around probable VS/Win64 compiler bug

src/types.h

 // Copyright 2014 the V8 project 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 V8_TYPES_H_
 #define V8_TYPES_H_
 
 #include "src/factory.h"
 #include "src/handles.h"
 #include "src/ostreams.h"
@@ skipping 257 matching lines @@
   typedef typename Config::template Handle<ConstantType>::type ConstantHandle;
   typedef typename Config::template Handle<RangeType>::type RangeHandle;
   typedef typename Config::template Handle<ContextType>::type ContextHandle;
   typedef typename Config::template Handle<ArrayType>::type ArrayHandle;
   typedef typename Config::template Handle<FunctionType>::type FunctionHandle;
   typedef typename Config::template Handle<UnionType>::type UnionHandle;
   typedef typename Config::Region Region;
 
   // Constructors.
 
+  // Explicitly mask, since VS on Win64 (wrongly?) sign extends the enum value.
   #define DEFINE_TYPE_CONSTRUCTOR(type, value)                                \
-    static TypeImpl* type() { return BitsetType::New(BitsetType::k##type); }  \
+    static TypeImpl* type() {                                                 \
+      return BitsetType::New(BitsetType::k##type & 0xffffffffu);              \
+    }                                                                         \
     static TypeHandle type(Region* region) {                                  \
-      return BitsetType::New(BitsetType::k##type, region);                    \
+      return BitsetType::New(BitsetType::k##type & 0xffffffffu, region);      \
     }
   BITSET_TYPE_LIST(DEFINE_TYPE_CONSTRUCTOR)
   #undef DEFINE_TYPE_CONSTRUCTOR
 
   static TypeHandle Class(i::Handle<i::Map> map, Region* region) {
     return ClassType::New(map, region);
   }
   static TypeHandle Constant(i::Handle<i::Object> value, Region* region) {
     // TODO(neis): Return RangeType for numerical values.
     return ConstantType::New(value, region);
@@ skipping 702 matching lines @@
   bool Narrows(BoundsImpl that) {
     return that.lower->Is(this->lower) && this->upper->Is(that.upper);
   }
 };
 
 typedef BoundsImpl<ZoneTypeConfig> Bounds;
 
 } }  // namespace v8::internal
 
 #endif  // V8_TYPES_H_