support bazel complie this project and format code.

learn_class/modern_cpp_30/SFINAE/SFINAE.cpp

@@ -0,0 +1,33 @@
+//
+// Created by light on 20-1-5.
+//
+#include <iostream>
+
+using namespace std;
+
+template <typename T> class IsClassT {
+private:
+  typedef char One;
+  typedef struct {
+    char a[2];
+  } Two;
+
+  template <typename C> static One test(int C::*);
+
+  // Will be chosen if T is anything except a class.
+  template <typename C> static Two test(...);
+
+public:
+  enum { Yes = sizeof(IsClassT<T>::test<T>(0)) == 1 };
+  enum { No = !Yes };
+};
+
+struct A {};
+
+int main() {
+  // 0不能转换为int int::*因为int不是类，所以它不能有成员指针。
+  cout << IsClassT<int>::Yes << endl;
+  cout << IsClassT<A>::Yes << endl;
+
+  return 0;
+}