[janitor] tools -Wwrite-strings cleanup

Daniel Marmier d.marmier at bluewin.ch
Fri Oct 15 11:43:31 CDT 2004

On Thursday 14 October 2004 02.55, Alexandre Julliard wrote:
> Daniel Marmier <d.marmier at bluewin.ch> writes:
> > This is one situation I would like to discuss a bit more.
> > Some code uses a mix of static and dynamic structures containing strings.
> > The static instances have constant strings, the others are xmalloc'd. These
> > strings must be declared char *, since we need to be able to free them. But
> > this prevents us from initializing the static ones with constant strings.
> >
> > Solution 1 (double casting to avoid constness removal warning)
> > 	s->name = FAKE_CHARPTR("hello");
> >
> > Solution 2 (shows clearly that we mix constant/variable and avoids casting):
> > 	union {
> > 		const char *c;
> > 		char *v;
> > 	} name;
> > 	s->name.c = "hello";
> >
> > Can you think of a better solution? What is preferable?
> I think this sort of construct should be avoided. If we mix static and
> allocated data in the same structure, there is a big risk that we will
> one day try to free static data, with random results. We should change
> the code so that it doesn't need that, either by storing the static
> data in a separate structure, or for non performance critical code by
> allocating a copy of the static data.

If such a risk exists, the latter change implies that we will silently free
the copy of the data instead of trying to free the static data. This could
lead to consider a simple test passed, while causing random results in
more complex code that still references the data ...

					Daniel Marmier

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