問題描述

string foo() { return "hello"; }
int main() 
{
    //below should be illegal for binding a non-const (lvalue) reference to a rvalue
    string& tem  = foo();   

    //below should be the correct one as only const reference can be bind to rvalue(most important const)
    const string& constTem = foo();   
}

1. GCC 是給出編譯錯誤的好方法:從 類型的臨時對象對 std::string& 類型的非常量引用無效初始化std::string
2. VS2008 還不錯，至少它給出了一個編譯警告:警告 C4239:使用了非標準擴展:正在初始化":從 std::string 到 std::string & 的轉換 非常量引用只能綁定到左值
3. 問題來了 - VS2010(SP1) 沒有任何問題錯誤或警告，為什么??！！我知道 VS2010 中的 rvalue reference 可用于綁定 rvalue 但我沒有使用 &&，而是在演示代碼中，我只是使用非常量左值引用！

1. GCC is the good one to give a compile error: invalid initialization of non-const reference of type std::string& from a temporary of type std::string
2. VS2008 is not too bad as at least it gives a compile warning: warning C4239: nonstandard extension used : 'initializing' : conversion from std::string to std::string & A non-const reference may only be bound to an lvalue
3. Here comes the problematic one - VS2010(SP1) comples fine WITHOUT any error or warning, WHY ??!! I know rvalue reference in VS2010 can be used to bind with rvalue but I am NOT using &&, instead in the demo code, I was just using non-const lvalue reference !

這里有人能幫我解釋一下VS2010的行為嗎?是bug嗎！?謝謝

Can somone help me explain the behavior of VS2010 here? Is it a bug !? Thanks

推薦答案

這是 VS 編譯器的已知問題/功能.他們一直允許這樣做，并且似乎沒有任何推動刪除該擴展.

That is a known issue/feature of the VS compilers. They have always allowed that and there does not seem to be any push into removing that extension.

這篇關于一個 VS2010 錯誤?允許在沒有警告的情況下綁定非常量引用到右值?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！