[cmake-developers] CheckSymbolExists.cmake

[Rolf Eike Beer]

Christopher Sean Morrison wrote:
> On Jun 04, 2013, at 04:17 PM, Brad King <brad.king at kitware.com> wrote:
> 
> > The discussion that led to that change was here:
> > 
> > http://thread.gmane.org/gmane.comp.programming.tools.cmake.devel/2523/focu
> > s=2530

> The predicating problem is curious.  If a pthreads library was no longer
> being detected, that would imply that CheckSymbolExists was failing, yes?
>  Getting optimized out of compilation would have resulted in the check
> *passing*...

The change was two-fold: the new check for pthreads was to first try if 
pthread is in the libc itself, i.e. no additional libraries need to be linked 
it. If you now have a gcc that drops the symbol before linking the linking 
will succeed on the first try, so FindThreads.cmake will think 
pthread_create() is in libc. But in fact it is not, and if you _really_ use 
the symbol you will get linker errors.

> It possible to quell that conversion warning.  Perhaps something like this:
>  ((char *)(long)&SYMBOL)[argc] + 1

This will cause errors on those platforms where long and void* are not the 
same size, i.e. Windows64.

Eike

P.S.: please fix your mailer to properly insert quote signs as otherwise the 
mail is very hard to understand.
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