[CMake] Problems resolving PTHREAD_* symbols.

[Rick McGuire]

This is still driving us crazy.  Digging a little deeper into this, the
symbols we need are defined as enums on Linux, which explains why
check_symbol_exists() does not work there.  The OSX pthread.h header uses
defines, but for some reason, the check_c_source_compiles method is still
failing.  We've updated our script to use

check_c_source_compiles("#include <pthread.h>
                         int main(int arg, char **argv) {
                         int tryme;
                         tryme = PTHREAD_MUTEX_ERRORCHECK;
                         return 0;}"
                        HAVE_PTHREAD_MUTEX_ERRORCHECK)
if (NOT DEFINED HAVE_PTHREAD_MUTEX_ERRORCHECK)
   check_symbol_exists(PTHREAD_MUTEX_ERRORCHECK "pthread.h"
HAVE_PTHREAD_MUTEX_ERRORCHECK)
endif ()


to try both methods, but this is still failing on the Mac and a couple
of the Linux versions we build for.


This is driving us nuts, since we don't understand why the
check_c_source_compiler check is not working.  Is there some way we
can get debug information about why the compile fails?  That might
give us some clues.


Rick


On Mon, Sep 22, 2014 at 12:06 PM, Rick McGuire <object.rexx at gmail.com>
wrote:

> We have some semaphore code that has conditional compilation based on
> #defines in config.h.  We're having problems with resolving the various
> PTHREAD_* symbols to get the correct values in config.h.  Our first attempt
> at this (done on Linux) used
>
> check_symbol_exists(PTHREAD_MUTEX_RECURSIVE "pthread.h" HAVE_PTHREAD_MUTEX_RECURSIVE)
>
>
> This did not pick the symbol up correctly.  Eventually, we got things to work by using
>
>
> check_c_source_compiles("#include <pthread.h>
>                          int main(int arg, char **argv) {
>                          int tryme;
>                          tryme = PTHREAD_MUTEX_RECURSIVE;
>                          return 0;}"
>                         HAVE_PTHREAD_MUTEX_RECURSIVE)
>
> and got everything to build cleanly.  Over the weekend, we tried building on OSX for the first time, and once again, we were not resolving that these symbols existed.  What are we missing here?  Is there some technique we should be using that will work across the various platforms?
>
>
> Rick
>
>
>
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