Fix Cpplint issues in framework/data_type.h and framework/feed_fetch_type.h (#10146)

* Fix CPPLint issues with data_type.h

* Fix CPPLint issues with feed_fetch_type.h

Author: abhinavarora

paddle/fluid/framework/data_type.h

@@ -13,6 +13,7 @@ See the License for the specific language governing permissions and
 limitations under the License. */
 
 #pragma once
+#include <string>
 #include <typeindex>
 #include "paddle/fluid/framework/framework.pb.h"
 #include "paddle/fluid/platform/enforce.h"
@@ -22,26 +23,28 @@ namespace paddle {
 namespace framework {
 
 inline proto::VarType::Type ToDataType(std::type_index type) {
-  using namespace paddle::framework::proto;
   if (typeid(platform::float16).hash_code() == type.hash_code()) {
     return proto::VarType::FP16;
-  } else if (typeid(float).hash_code() == type.hash_code()) {
+  } else if (typeid(const float).hash_code() == type.hash_code()) {
+    // CPPLint complains Using C-style cast.  Use static_cast<float>() instead
+    // One fix to this is to replace float with const float because
+    // typeid(T) == typeid(const T)
+    // http://en.cppreference.com/w/cpp/language/typeid
     return proto::VarType::FP32;
-  } else if (typeid(double).hash_code() == type.hash_code()) {
+  } else if (typeid(const double).hash_code() == type.hash_code()) {
     return proto::VarType::FP64;
-  } else if (typeid(int).hash_code() == type.hash_code()) {
+  } else if (typeid(const int).hash_code() == type.hash_code()) {
     return proto::VarType::INT32;
-  } else if (typeid(int64_t).hash_code() == type.hash_code()) {
+  } else if (typeid(const int64_t).hash_code() == type.hash_code()) {
     return proto::VarType::INT64;
-  } else if (typeid(bool).hash_code() == type.hash_code()) {
+  } else if (typeid(const bool).hash_code() == type.hash_code()) {
     return proto::VarType::BOOL;
   } else {
     PADDLE_THROW("Not supported");
   }
 }
 
 inline std::type_index ToTypeIndex(proto::VarType::Type type) {
-  using namespace paddle::framework::proto;
   switch (type) {
     case proto::VarType::FP16:
       return typeid(platform::float16);
@@ -62,7 +65,6 @@ inline std::type_index ToTypeIndex(proto::VarType::Type type) {
 
 template <typename Visitor>
 inline void VisitDataType(proto::VarType::Type type, Visitor visitor) {
-  using namespace paddle::framework::proto;
   switch (type) {
     case proto::VarType::FP16:
       visitor.template operator()<platform::float16>();
@@ -88,7 +90,6 @@ inline void VisitDataType(proto::VarType::Type type, Visitor visitor) {
 }
 
 inline std::string DataTypeToString(const proto::VarType::Type type) {
-  using namespace paddle::framework::proto;
   switch (type) {
     case proto::VarType::FP16:
       return "float16";

paddle/fluid/framework/feed_fetch_type.h

@@ -13,7 +13,6 @@ See the License for the specific language governing permissions and
 limitations under the License. */
 
 #pragma once
-#include <string>
 #include <vector>
 #include "paddle/fluid/framework/lod_tensor.h"
 
@@ -22,7 +21,8 @@ namespace framework {
 using FeedFetchType = LoDTensor;
 using FeedFetchList = std::vector<FeedFetchType>;
 
-static const std::string kFeedOpType = "feed";
-static const std::string kFetchOpType = "fetch";
+static const char kFeedOpType[] = "feed";
+static const char kFetchOpType[] = "fetch";
+
 }  // namespace framework
 }  // namespace paddle