treat enum,bool as 32bit; shrink ReadVarint32

src/google/protobuf/map_type_handler.h

@@ -467,11 +467,11 @@ inline const char* ReadSINT32(const char* ptr, int32* value) {
 }
 template <typename E>
 inline const char* ReadENUM(const char* ptr, E* value) {
-  *value = static_cast<E>(ReadVarint64(&ptr));
+  *value = static_cast<E>(ReadVarint32(&ptr));
   return ptr;
 }
 inline const char* ReadBOOL(const char* ptr, bool* value) {
-  *value = static_cast<bool>(ReadVarint64(&ptr));
+  *value = static_cast<bool>(ReadVarint32(&ptr));
   return ptr;
 }
 

src/google/protobuf/parse_context.h

@@ -586,9 +586,9 @@ inline uint64 ReadVarint64(const char** p) {
 }
 
 inline uint32 ReadVarint32(const char** p) {
-  uint64 tmp;
+  uint32 tmp;
   *p = VarintParse(*p, &tmp);
-  return static_cast<uint32>(tmp);
+  return tmp;
 }
 
 inline int64 ReadVarintZigZag64(const char** p) {