remove a custom implementation of std::enable_if

googletest/include/gtest/gtest-matchers.h

@@ -42,6 +42,7 @@
 #include <memory>
 #include <ostream>
 #include <string>
+#include <type_traits>
 
 #include "gtest/gtest-printers.h"
 #include "gtest/internal/gtest-internal.h"
@@ -299,8 +300,8 @@ class MatcherBase {
   template <typename U>
   explicit MatcherBase(
       const MatcherInterface<U>* impl,
-      typename internal::EnableIf<
-          !internal::IsSame<U, const U&>::value>::type* = nullptr)
+      typename std::enable_if<!internal::IsSame<U, const U&>::value>::type* =
+          nullptr)
       : impl_(new internal::MatcherInterfaceAdapter<U>(impl)) {}
 
   MatcherBase(const MatcherBase&) = default;
@@ -333,9 +334,10 @@ class Matcher : public internal::MatcherBase<T> {
       : internal::MatcherBase<T>(impl) {}
 
   template <typename U>
-  explicit Matcher(const MatcherInterface<U>* impl,
-                   typename internal::EnableIf<
-                       !internal::IsSame<U, const U&>::value>::type* = nullptr)
+  explicit Matcher(
+      const MatcherInterface<U>* impl,
+      typename std::enable_if<!internal::IsSame<U, const U&>::value>::type* =
+          nullptr)
       : internal::MatcherBase<T>(impl) {}
 
   // Implicit constructor here allows people to write

googletest/include/gtest/gtest.h

@@ -292,7 +292,7 @@ class GTEST_API_ AssertionResult {
   template <typename T>
   explicit AssertionResult(
       const T& success,
-      typename internal::EnableIf<
+      typename std::enable_if<
           !std::is_convertible<T, AssertionResult>::value>::type*
       /*enabler*/
       = nullptr)

googletest/include/gtest/internal/gtest-internal.h

@@ -991,13 +991,6 @@ struct IsRecursiveContainerImpl<C, true> {
 template <typename C>
 struct IsRecursiveContainer : public IsRecursiveContainerImpl<C>::type {};
 
-// EnableIf<condition>::type is void when 'Cond' is true, and
-// undefined when 'Cond' is false.  To use SFINAE to make a function
-// overload only apply when a particular expression is true, add
-// "typename EnableIf<expression>::type* = 0" as the last parameter.
-template<bool> struct EnableIf;
-template<> struct EnableIf<true> { typedef void type; };  // NOLINT
-
 // Utilities for native arrays.
 
 // ArrayEq() compares two k-dimensional native arrays using the