Octavio,
How would you propose addressing this issue? I split my monster patch
file and reduced it to 31437 lines (roughly 60,000 lines of the patch
turned out to be gettext data that didn't get erased in a make clean) to
just insert "(char *)" on the 6727 lines of code producing this warning
(yes, I counted). String constants are a fact of life and making
everything modifiable is impractical. Just by masking the Char *
warnings, I found a handful of compiler warnings that pointed to real
problems(I will be submitting those patches soon).
Regards,
Paul
On Wed, 2011-09-07 at 18:12 -0700, Octavio Alvarez wrote:
> On Wed, 07 Sep 2011 17:08:08 -0700, Paul Taggart <ptagg...@cinci.rr.com>
> wrote:
> >> It is wrong. You have to use 'const char*' in places where you use
> >> these strings.
> >> This enables compiler to store only one copy of identical texts and
> >> identifie places where someone tries to modify string constant (it is
> >> a bug). I have done this in my branch.
> >
> > No, this is not a bug. the called functions are looking for a pointer to
> > a string (char *). By just providing a quoted string, you are providing
> > the function with the entire string, not just the pointer. The compiler
> > recognizes this discrepancy and automatically creates the pointer
>
> By providing a string literal you are providing the function with a
> pointer to read-only data. If you ever *ever* try to modify any
> character in this region, you will get a segmentation fault.
>
> > but
> > unlike gcc which has the default option -Wno-write-strings, g++ defaults
> > to -Wwrite-strings which issues a warning message : "warning: deprecated
> > conversion from string constant to ‘char*’" for each occurrence.
> > The easy fix would be to add -Wno-write-strings to CXXFLAGS in all of the
> > Makefiles (can be set in configure.in) but I'm a bit of a purest who
> > believes its better to fix the problem than to mask it.
>
> I think we all agree on that: -Wno-write-strings is just masking the
> problem. However, adding (char *) to deprecated conversions from
> (const char *) is actually worse, as it will not only mask the problem but
> will also allow some functions to modify potentially immutable strings,
> and thus make Cinelerra more crash-prone.
>
> When you code something like this:
>
> char * x = "abcde";
> x[3] = '4';
>
> g++ warns about the mistake. If you just shut it up by casting it to
> (char *) like this:
>
> char * x = (char *) "abcde";
> x[3] = '4';
>
> The compiler will not warn you and your program will still crash!
> This is bad!
>
> The correct fix (in this case only) is actually:
>
> char * x = strdup("abcde");
> x[3] = '4';
>
> But you can not abuse this or you will end up wasting memory badly.
>
>
