support bazel complie this project and format code.

learn_class/modern_cpp_30/obj/obj2.cpp

@@ -0,0 +1,46 @@
+//
+// Created by light on 19-12-22.
+//
+
+// nrvo example
+
+#include <iostream>
+
+using namespace std;
+
+// Can copy and move
+class A {
+public:
+  A() { cout << "Create A\n"; }
+
+  ~A() { cout << "Destroy A\n"; }
+
+  A(const A &) { cout << "Copy A\n"; }
+
+  A(A &&) { cout << "Move A\n"; }
+
+  A &operator=(const A &a) {
+    std::cout << "copy assignment" << std::endl;
+    return *this;
+  }
+
+  A &operator=(A &&a) {
+    cout << "move assignment\n";
+    return *this;
+  }
+};
+
+// 编译器可以优化 返回值移动出去
+A getA_named() {
+  A a;
+  return a;
+}
+
+int main() {
+  //    cout<<"拷贝"<<endl;
+  //    auto a = getA_named();
+
+  cout << "赋值" << endl;
+  A aa;
+  aa = getA_named();
+}