On Fri, Dec 10, 2010 at 15:34:32 +0100, Abderrahim Kitouni wrote:
> Hello,
> في ج، 10-12-2010 عند 00:40 -0300 ، كتب Erick Pérez Castellanos:
> > Is this a bug ???
> >
> > I'm using Glib.Settings API, and specifically this:
> > public bool set_strv (string key, [CCode (array_length = false)]
> > string[] value)
> > from that class and when using as it says passing an string array as second
> > parameters I'm getting a warning from the compiler:
> > spider_window.c: In function ‘spider_window_edit_preferences_callback’:
> > spider_window.c:811:3: warning: passing argument 3 of ‘g_settings_set_strv’
> > from incompatible pointer type
> > /usr/include/glib-2.0/gio/gsettings.h:124:25: note: expected ‘const gchar *
> > const*’ but argument is of type ‘char **’
> >
> > And that shouldn't happen.
>
> "shouldn't happen" may be too strong :-)
> We would like valac generated code to compile without warning, but
> that's not an easy task and it doesn't bring much.
>
> And btw, I don't see what problem there could be when passing char** to
> a "const gchar* const*", maybe your compiler is a bit too paranoid? (and
> maybe there is a complicated corner case I don't see).
Well, you can't cast 'char **' to 'const char **' safely (applies to any
type, not just char, of course). Consider:
void get_message(const char **msg)
{
*msg = "All is wrong!";
}
...
char *msg;
get_message(&msg);
msg[0] = 'B'; /* OOPS! You modified the static buffer! */
The danger does NOT apply to 'char **' -> 'char const * const *', since than
nothing of the structure may be modified, but gcc may not be smart enough to
avoid the warning in this case.
--
Jan 'Bulb' Hudec <[email protected]>
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