Must use partial specialization

Signed-off-by: Shane Loretz <[email protected]>

Author: sloretz

include/eigenpy/numpy.hpp

@@ -55,7 +55,7 @@ void EIGENPY_DLLAPI import_numpy();
 int EIGENPY_DLLAPI PyArray_TypeNum(PyTypeObject* type);
 
 // By default, the Scalar is considered as a Python object
-template <typename Scalar>
+template <typename Scalar, typename Enable = void>
 struct NumpyEquivalentType {
   enum { type_code = NPY_USERDEF };
 };
@@ -141,12 +141,16 @@ struct NumpyEquivalentType<unsigned long> {
 
 #include <type_traits>
 
-template <>
-struct NumpyEquivalentType<std::enable_if<!std::is_same<int64_t, long long>::value, long long>::type> {
+template <typename Scalar>
+struct NumpyEquivalentType<Scalar, std::enable_if_t<
+    !std::is_same<int64_t, long long>::value &&
+    std::is_same<Scalar, long long>::value>> {
   enum { type_code = NPY_LONGLONG };
 };
-template <>
-struct NumpyEquivalentType<std::enable_if<!std::is_same<uint64_t, unsigned long long>::value, unsigned long long>::type> {
+template <typename Scalar>
+struct NumpyEquivalentType<Scalar, std::enable_if_t<
+    !std::is_same<uint64_t, unsigned long long>::value &&
+    std::is_same<Scalar, unsigned long long>::value>> {
   enum { type_code = NPY_ULONGLONG };
 };