Re: [Boost-users] 1.45: thread/condition_variable.hpp: unused variable 'res' warning, gcc 4.2

Subject: Re: [Boost-users] 1.45: thread/condition_variable.hpp: unused variable 'res' warning, gcc 4.2
From: Anthony Williams (anthony.ajw_at_[hidden])
Date: 2011-01-06 17:54:22

Dean Michael Berris <mikhailberis_at_[hidden]> writes:

> On Thu, Jan 6, 2011 at 9:28 PM, Anthony Williams <anthony.ajw_at_[hidden]> wrote:
>> "Hicham Mouline" <hicham_at_[hidden]> writes:
>>
>>> in Release build in Xcode, gcc 4.2.1,
>>>
>>> inline void condition_variable::wait(unique_lock<mutex>& m)
>>> {
>>> ...
>>> Â int const res = pthread_cond_wait(&cond, &internal_mutex);
>>> Â BOOST_ASSERT(!res);
>>> Â ...
>>> }
>>>
>>> Unused variable 'res'
>>>
>>> is gcc mistaken?
>>
>> Yes and no :-)
>>
>> In the release build the assert compiles to nothing, so res is no longer
>> referenced, even though it is referenced in the source.
>>
>
> I actually have a patch for this:
> https://svn.boost.org/trac/boost/ticket/4818 which I don't think has
> been merged into (or acted upon) yet.

I've changed it to throw rather than assert, for consistency with
condition_variable_any. This should get rid of the warning too.

Anthony
-- 
Author of C++ Concurrency in Action     http://www.stdthread.co.uk/book/
just::thread C++0x thread library             http://www.stdthread.co.uk
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