Question

In the project .pro file I’ve specified:

QMAKE_CXXFLAGS += -fno-exceptions  

Yet I’m able to throw exceptions in my app. Any thoughts on that?

Example: This shouldn’t work, but it works

#include <QApplication>
#include <QtDebug>

int main(int c, char**v)
{
    QApplication app(c,v);
    try
    {
        throw 1;
    }
    catch(int i)
    {

    }
    return app.exec();
}

Answer 1

You do not turn off exceptions by setting QMAKE_CXXFLAGS because this options is handled by CONFIG. You should use

CONFIG-=exceptions

to turn them off.

See the g++ args when you have neither QMAKE_CXXFLAGS nor CONFIG settings changed:

g++ -c -O2 -frtti -fexceptions -mthreads -Wall <...> main.cpp

Now, let’s set QMAKE_CXXFLAGS: get

g++ -c -fno-exceptions -O2 -frtti -fexceptions -mthreads -Wall <...> main.cpp

Ooops, we get our -fno-exceptions is overridden by CONFIG‘s -fexceptions.
Now, let’s set CONFIG:

g++ -c -O2 -frtti -Wall -fno-exceptions <...> main.cpp
mingw32-make.exe[1]: Leaving directory `G:/proj/ingeritance'
main.cpp: In function 'int qMain(int, char**)':
main.cpp:22:15: error: exception handling disabled, use -fexceptions to enable
mingw32-make.exe[1]: *** [release/main.o] Error 1
mingw32-make.exe: *** [release] Error 2

Oh! compilation error!