[cairo-bugs] [Bug 58727] warn_unused_result noise

[bugzilla-daemon at freedesktop.org]

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

--- Comment #8 from Bill Spitzak <spitzak at gmail.com> ---
On 05/12/2014 11:28 PM, bugzilla-daemon at freedesktop.org wrote:
> *Comment # 7 <https://bugs.freedesktop.org/show_bug.cgi?id=58727#c7> on
> bug 58727 <https://bugs.freedesktop.org/show_bug.cgi?id=58727> from Ravi
> Nanjundappa <mailto:nravi.n at samsung.com> *
>
> (In reply tocomment #6  <show_bug.cgi?id=58727#c6>)
>> I think the complaint is about strtol(), which is being used apparently
>> to find the other end of the numeric value (returned in the char** arg)
>> while the number is ignored, thus causing this error.
>>
>> It does seem that nobody is going to "accidentally" ignore the result of
>> strtol. The warning really should be on functions returning things you
>> *must* do something with, for instance malloc() where if you don't free
>> the returned value you have a memory leak.
>>
>> And they really should restore the (void)fn() work-around, which is
>> readable.
>
> In some of the cases (for ex: _cairo_polygon_add_external_edge()), the return
> values of the callee are used by the caller (for ex: ln. no. 63 and 177 in
> cairo-path-fill.c file), while in other cases it is ignored for some reasons.
> The warnings are thrown in these scenarios. In such a case, I fell like we can
> use the approach provided by Sergey Shandar, @
> http://stackoverflow.com/questions/3614691/casting-to-void-doesnt-remove-warn-unused-result-error
>
> Bill,
> Could you please share your opinion on this?

My tests just confirm that the ridiculous workaround described in the 
link (of using a temporary and casting *that* to void) is required by 
gcc, instead of the more sensible workaround of casting the function 
call to void.

I have no opinion on whether removing the warn-unused-result attribute 
from that function, or adding the workaround, or figuring out if the 
code should in fact should be paying attention to the result.

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