EXC_BAD_ACCESS with lambda capture

首先，請原諒，如果這看起來很明顯 - 我對C++很陌生。我一直在尋找這個，但我沒有發現任何特別有用的東西。EXC_BAD_ACCESS with lambda capture

當試圖訪問lambda內的捕獲變量時，我的應用程序崩潰，我不知道爲什麼。我不認爲這個對象已經被刪除，就像在崩潰的地方放置一個斷點並使用CLion的調試器一樣，CLion顯示該對象存在。

一個代碼示例可能會幫我解釋一下這個：

//Create the progress dialog 
QProgressDialog *progDialog = new QProgressDialog(tr("Opening Project…\nExtracted: 0 (0.0%)\nWaiting…"), nullptr, 0, 0, this); 

// ... Some code here 

//Declare a function to be passed as a callback 
std::function<void (int minValue, int maxValue)> *progRangeChangedCallback = nullptr; 

// ... More code here 

//Create the lambda 
//I capture progDialog (The progress dialog) 
auto progRangeChangedCallbackLambda = [&progDialog](int newMin, int newMax) { 
    //Putting a breakpoint here reveals that progDialog exists 
    //CLion even autocompletes the below functions 
    //when trying to evaluate an expresion 
    progDialog->setMinimum(newMin); //EXC_BAD_ACCESS: Crashes happen here! 
    progDialog->setMaximum(newMax); 
}; 

// ... Even more code here 

//Put the lambda in a std::function 
progRangeChangedCallback = new std::function<void (int minValue, int maxValue)>(progRangeChangedCallbackLambda); 

// ... More code 

//Pass the std::function object as a callback to a new thread 
//This extends QThread 
OpenProjectThread *thread = new OpenProjectThread(filePath, this, progChangedCallback, progRangeChangedCallback, onSuccessCallback, onErrorCallback); 
thread->start();

來源

2016-08-20 CraftedCart