FIX: restricting c++ template usage to POD types

paddle/framework/detail/tensor-inl.h

@@ -44,12 +44,14 @@ inline T* Tensor::data() {
 
 template <typename T>
 inline T* Tensor::mutable_data(DDim dims, platform::Place place) {
+  static_assert(std::is_pod<T>::value, "T must be POD");
   Resize(dims);
   return mutable_data<T>(place);
 }
 
 template <typename T>
 inline T* Tensor::mutable_data(platform::Place place) {
+  static_assert(std::is_pod<T>::value, "T must be POD");
   PADDLE_ENFORCE(product(dims_) > 0,
                  "Tensor's numel must be larger than zero to call "
                  "Tensor::mutable_data. Call Tensor::set_dim first.");

paddle/memory/memory.h

@@ -29,10 +29,10 @@ void Free(Place, void*);
 template <typename Place>
 size_t Used(Place);
 
-template <typename T, /* must be POD types */
-          typename Place /* platform::GPUPlace or platform::CPUPlace */,
-          typename std::enable_if<std::is_pod<T>::value>::type* = nullptr>
+template <typename T, typename Place>
 class PODDeleter {
+  static_assert(std::is_pod<T>::value, "T must be POD");
+
  public:
   PODDeleter(Place place) : place_(place) {}
   void operator()(T* ptr) { Free(place_, static_cast<void*>(ptr)); }