Can someone explain why this while loop exits immediately even though the condition is true?

bool cond = false;

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    while ( cond == false ) ;

    std::cout << " while loop completed " << std::endl;

    return a.exec();
}

If we rewrite the loop to something like this, then it works as expected , i.e. it loops as long cond is set to false.

 while( true ){
            if( cond )
                break;
        }

cond is a global variable and if we were to change it to a local variable, then the first (and second) while would loop infinitely.

This was built with a MingGW64 compiler in release mode.