[Bug c++/98345] Different behaviour of gcc Versions (<=8, >=9)

[budek at wtal dot de via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98345

--- Comment #4 from Peter Budek <budek at wtal dot de> ---
The requested test-case:

#include <iostream>
#include <QtCore/QList>

int main(int argc, char *argv[])
{
   QList<int> l ;

   l.append(1) ;    
   l.append(2) ;
   l.append(3) ;
   foreach(int i, l) std::cout << i << std::endl ;  

   return(0) ;
}

The result is '1' with gcc 10.2.0 (not 1 2 3).
I found this compiling qucs (http://qucs.sourceforge.net/index.html).

patching qt helps:
+++ qt-everywhere-opensource-src-4.8.7/src/corelib/global/qglobal.h    
2020-12-17 10:46:30.000000000 +0100
@@ -2496,9 +2496,9 @@
 #define Q_FOREACH(variable, container)                                \
 for (QForeachContainer<__typeof__(container)> _container_(container); \
      !_container_.brk && _container_.i != _container_.e;              \
      __extension__  ({ ++_container_.brk; ++_container_.i; }))                
      \
-    for (variable = *_container_.i;; __extension__ ({--_container_.brk;
break;}))
+    for (variable = *_container_.i;!_container_.brk; __extension__
({--_container_.brk;}))

 #else

 struct QForeachContainerBase {};