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List:       asterisk-dev
Subject:    Re: [asterisk-dev] [Code Review] 4554: clang compiler warning: -Wunused-value
From:       "rmudgett" <reviewboard () asterisk ! org>
Date:       2015-03-31 22:30:06
Message-ID: 20150331223006.28317.6906 () sonic ! digium ! api
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https://reviewboard.asterisk.org/r/4554/#review14999
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I dislike this warning.  It is more nuisance than helpful.  I once worked with \
compiler that had a similar warning.  The lengths you sometimes have to go to \
eradicate the the warning can be extream.

There are several places in this patch that change code behavior and introduce bugs.

- rmudgett


On March 28, 2015, 7:44 p.m., Diederik de Groot wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/4554/
> -----------------------------------------------------------
> 
> (Updated March 28, 2015, 7:44 p.m.)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Bugs: ASTERISK-24917
> https://issues.asterisk.org/jira/browse/ASTERISK-24917
> 
> 
> Repository: Asterisk
> 
> 
> Description
> -------
> 
> clang's static analyzer will throw quite a number warnings / errors during \
> compilation, some of which can be very helpfull in finding corner-case bugs.  
> clang compiler warning:-Wunused-value
> 
> Changes:
> apps/app_agent_pool.c
> multiple occasions where return value from ast_channel_ref and ast_channel_unref is \
> not checked not used. return value from AST_LIST_REMOVE should be checked.
> Possible issues with leaked logged reference (added remark)
> 
> channels/chan_iax2.c
> return values from ast_callid_ref and ast_callid_unref can/should be used to update \
> the pointer return value from AST_SCHED_DEL should be used to update the scheduled \
> variable return value from AST_LIST_REMOVE should be checked.
> 
> channels/iax2/parser.c
> return value from AST_LIST_REMOVE should be checked.
> 
> include/asterisk/stringfields.h
> Quick fix to send the returned value from ast_string_field_ptr_set into the void.
> 
> Work in Progress:
> There are too many sources issues with "-Wunused-value" for one person to create \
> all the fixes. If we want to actually use this warning we will need a couple of \
> extra hands-on. 
> Should we suppress "-Wunused-value" ? :
> I think some of the issues pointed out by clang could be very helpfull, for example \
> the "unref/ref/AST_LIST_REMOVE" changes that where needed in chan_iax2.c and \
> apps/app_agent_pool.c. Some others a less interesting, for example the SCHED_DEL \
> fixes. 
> 
> Diffs
> -----
> 
> /branches/13/include/asterisk/stringfields.h 433444 
> /branches/13/channels/iax2/parser.c 433444 
> /branches/13/channels/chan_iax2.c 433444 
> /branches/13/apps/app_agent_pool.c 433444 
> 
> Diff: https://reviewboard.asterisk.org/r/4554/diff/
> 
> 
> Testing
> -------
> 
> 
> File Attachments
> ----------------
> 
> ASTCFLAGS="-Wno-error=unused-value" make &| grep "[-W" -B1 -A2
> https://reviewboard.asterisk.org/media/uploaded/files/2015/03/28/83f2f382-9ef2-41cf-8e7a-c188c014c17e__make.report
>  
> 
> Thanks,
> 
> Diederik de Groot
> 
> 


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 <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;">I dislike this warning.  \
It is more nuisance than helpful.  I once worked with compiler that had a similar \
warning.  The lengths you sometimes have to go to eradicate the the warning can be \
extream.

There are several places in this patch that change code behavior and introduce \
bugs.</pre>  <br />









<p>- rmudgett</p>


<br />
<p>On March 28th, 2015, 7:44 p.m. CDT, Diederik de Groot wrote:</p>








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<div>Review request for Asterisk Developers.</div>
<div>By Diederik de Groot.</div>


<p style="color: grey;"><i>Updated March 28, 2015, 7:44 p.m.</i></p>







<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>


 <a href="https://issues.asterisk.org/jira/browse/ASTERISK-24917">ASTERISK-24917</a>


</div>



<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt;">Repository: </b>
Asterisk
</div>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
 <table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">clang&#39;s static analyzer will throw quite a number warnings / errors \
during compilation, some of which can be very helpfull in finding corner-case bugs. 

clang compiler warning:-Wunused-value

Changes:
apps/app_agent_pool.c
multiple occasions where return value from ast_channel_ref and ast_channel_unref is \
not checked not used. return value from AST_LIST_REMOVE should be checked.
Possible issues with leaked logged reference (added remark)

channels/chan_iax2.c
return values from ast_callid_ref and ast_callid_unref can/should be used to update \
the pointer return value from AST_SCHED_DEL should be used to update the scheduled \
variable return value from AST_LIST_REMOVE should be checked.

channels/iax2/parser.c
return value from AST_LIST_REMOVE should be checked.

include/asterisk/stringfields.h
Quick fix to send the returned value from ast_string_field_ptr_set into the void.

Work in Progress:
There are too many sources issues with &quot;-Wunused-value&quot; for one person to \
create all the fixes. If we want to actually use this warning we will need a couple \
of extra hands-on.

Should we suppress &quot;-Wunused-value&quot; ? :
I think some of the issues pointed out by clang could be very helpfull, for example \
the &quot;unref/ref/AST_LIST_REMOVE&quot; changes that where needed in chan_iax2.c \
and apps/app_agent_pool.c. Some others a less interesting, for example the SCHED_DEL \
fixes.</pre>  </td>
 </tr>
</table>



<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">

 <li>/branches/13/include/asterisk/stringfields.h <span style="color: \
grey">(433444)</span></li>

 <li>/branches/13/channels/iax2/parser.c <span style="color: \
grey">(433444)</span></li>

 <li>/branches/13/channels/chan_iax2.c <span style="color: grey">(433444)</span></li>

 <li>/branches/13/apps/app_agent_pool.c <span style="color: \
grey">(433444)</span></li>

</ul>

<p><a href="https://reviewboard.asterisk.org/r/4554/diff/" style="margin-left: \
3em;">View Diff</a></p>



<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">File Attachments \
</h1>

<ul>

 <li><a href="https://reviewboard.asterisk.org/media/uploaded/files/2015/03/28/83f2f38 \
2-9ef2-41cf-8e7a-c188c014c17e__make.report">ASTCFLAGS=&quot;-Wno-error=unused-value&quot; \
make &amp;| grep &quot;[-W&quot; -B1 -A2</a></li>

</ul>





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