QFlags type resolution (unexpectedly resolved as int)

This review
https://git.reviewboard.kde.org/r/118016/

triggered an interesting question, since this code:

#include <stdio.h>
#include <QFlags>

enum Foo { Foo1 = 1, Foo2 = 2};
enum Bar { Bar1 = 1, Bar2 = 2};

Q_DECLARE_FLAGS(Foos, Foo)
Q_DECLARE_OPERATORS_FOR_FLAGS(Foos)
Q_DECLARE_FLAGS(Bars, Bar)
Q_DECLARE_OPERATORS_FOR_FLAGS(Bars)

void fooBar(Foos foo, Bars bar, int i = 5)
{
    printf("foo bar int\n");
}

void fooBar(Foos foo, int i = 5)
{
    printf("foo int\n");
}

int main(int, char **)
{
    fooBar(Foo1, Bar1);
    fooBar(Foo1, Bar1|Bar2);
}

g++ -fPIC `pkg-config --libs --cflags Qt5Core` -o enum_cast enum_cast.cpp
g++ `pkg-config --libs --cflags QtCore` -o enum_cast enum_cast.cpp

produces this output:

   foo int
   foo bar int

on Qt4 & Qt5 (g++ (GCC) 4.8.2 20140206 (prerelease))

Ie. the or'd Flag is resolved as "Bars", but the simple Flag is resolved as int

That seems unexpectable to me - it should be

   foo bar int
   foo bar int

Notice that

• the Q_DECLARE_OPERATORS_FOR_FLAGS macro does not trigger the behavior, it's part of QFlags (w/o you'd get "foo int" twice)
• using "dumb" enums will get you the (expectable) output

     foo bar int
     foo int  
  

There's https://bugreports.qt-project.org/browse/QTBUG-13577 which seems related was closed invalid, since flags have to be power of two, but that is not the issue here (1, 2 are 2^x|x=0,1 - I had 0,1 before, what should according to the deco still be fine, but causes the same behavior)