[Bug c++/49679] Increment/decrement operator (++/--) not working as expected

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49679

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-07-08 
18:37:41 UTC ---
(In reply to comment #3)
> a and b must be the same.

No, it's undefined behaviour. Anything can happen.

http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html