[Interest] [SOLVED] Re: Compiling Programs with C++11 with Qt5, which was compiled without C++11 flag. Possible?

[Guido Seifert]

You are great. On the spot with your error analysis. (This is a general response to all, who helped brainstorming) :-)
I just found this on SO:

> Yay, someone (JKSH) found what the problem was on Qt Project forums (here).

> In short: The problem was that I had written somewhere #define I complex(0.0, 1.0), 
> which created a name clash in qobjectdefs_impl.h (where complex was a typedef for 
> std::complex<double>). For some (weird) reason that didn’t cause any problems as long 
> as I didn’t write CONFIG = c+11 in the pro file, but not it did after writing it.

Guido