support bazel complie this project and format code.

learn_class/modern_cpp_30/reference/ref.cpp

@@ -0,0 +1,55 @@
+//
+// Created by light on 19-12-15.
+//
+
+#include <iostream> // std::cout/endl
+#include <utility> // std::move
+using namespace std;
+class Obj {
+public:
+    Obj()
+    {
+        cout << "Obj()" << endl;
+    }
+    Obj(const Obj&)
+    {
+        cout << "Obj(const Obj&)"
+             << endl;
+    }
+    Obj(Obj&&)
+    {
+        cout << "Obj(Obj&&)" << endl;
+    }
+};
+Obj simple()
+{
+    Obj obj;
+// 简单返回对象；一般有 NRVO
+    return obj;
+}
+Obj simple_with_move()
+{
+    Obj obj;
+// move 会禁止 NRVO
+    return std::move(obj);
+}
+Obj complicated(int n)
+{
+    Obj obj1;
+    Obj obj2;
+    // 有分支，一般无 NRVO
+    if (n % 2 == 0) {
+        return obj1;
+    } else {
+        return obj2;
+    }
+}
+int main()
+{
+    cout << "*** 1 ***" << endl;
+    auto obj1 = simple();
+    cout << "*** 2 ***" << endl;
+    auto obj2 = simple_with_move();
+    cout << "*** 3 ***" << endl;
+    auto obj3 = complicated(42);
+}