[cairo-bugs] [Bug 58727] warn_unused_result noise

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=58727

--- Comment #4 from Ravi Nanjundappa <nravi.n at samsung.com> ---
(In reply to comment #3)
> Oh god those gnu-idiots!
> 
> I tried it and in fact the multi-line workaround is the only thing that 
> works. Or a wrapper function. Compile the following with -Wall:
> 
> int fn () __attribute__ ((warn_unused_result));
> 
> int used(int i) { return i; }
> 
> int main(int argc, const char** argv)
> {
>    int a, b;
>    fn(); /* produces error! */
>    (void)fn(); /* produces error! This used to work!*/
>    a = fn(); /* produces warning that a is unused */
>    b = fn(); (void)b; /* this works */
>    used(fn()); /* this also works */
>    return 0;
> }
> 

Agreed. But in the wrapper function approach, we will have to change the
declarations of all the cairo functions, for which the return values are really
not used anywhere. 

> 
> On 05/06/2014 07:20 AM, bugzilla-daemon at freedesktop.org wrote:
> > *Comment # 2 <https://bugs.freedesktop.org/show_bug.cgi?id=58727#c2> on
> > bug 58727 <https://bugs.freedesktop.org/show_bug.cgi?id=58727> from
> > Daniel Macks <mailto:dmacks at netspace.org> *
> >
> > I'm not a machine with compilers right now to test, but you cast the
> > function-call to void rather than assigning to a temp-variable? Instead of:
> >
> > int unused;
> > unused=some_function_with_attribute_wur(foo);
> > (void) unused;
> >
> > Just:
> >
> > (void) some_function_with_attribute_wur(foo);
> >
> > ------------------------------------------------------------------------
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