使用clang和gcc编译时,代码不调用Move构造函数

Question

使用clang和gcc编译时,代码不调用Move构造函数

dak*_*akt 3 c++ gcc clang visual-c++ c++11

所以,这在GCC,CLANG和MSVC上编译得很好但是给出了不同的输出:

#include <iostream>
using namespace std;

class A {
 public:
    A() {
        cout << this << " def" << endl;
    }
    A(const A&) {
        cout << this << " copy" << endl;
    }
    A(A&&) {
        cout << this << " move" << endl;
    }
    A& operator= (const A&) {
        cout << this << " copy=" << endl;
        return *this;
    }
    A& operator= (A&&) {
        cout << this << " move=" << endl;
        return *this;
    }

    ~A() {
        cout << this << " ~A" << endl;
    }
};

A f() { 
    A a;
    return a; 
}

int main(){
    A a = f();
}

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使用GCC和CLANG输出: