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

Dean Michael Berris writes:

On Thu, Jan 6, 2011 at 9:28 PM, Anthony Williams wrote:

...

"Hicham Mouline" writes:

...

in Release build in Xcode, gcc 4.2.1,

inline void condition_variable::wait(unique_lock<mutex>& m) { ...  int const res = pthread_cond_wait(&cond, &internal_mutex);  BOOST_ASSERT(!res);  ... }

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 Just Software Solutions Ltd http://www.justsoftwaresolutions.co.uk 15 Carrallack Mews, St Just, Cornwall, TR19 7UL, UK. Company No. 5478976