Is this a gcc bug?

[Joern Rennecke]

> Warning: Multiple uses of 'x' in statement modifying 'x'.  Statement results
> are implementation dependant.  Randomizer invoked to minimize predicability.
> Attempting to reformat all Hard Drives: Failed.

The standard only talks about undefined behaviour at program run time, not
at compile time.

Of course, you could argue that the standard doesn't forbid you to reformat
all hard drives at compilation time, but then, you could do that irrespective
of the input program.  I'd say that's a quality of implementation issue.