[CMake] FindThreads: the odd one out?

[Marcel Loose]

On Fri, 2009-09-04 at 21:55 +0200, Alexander Neundorf wrote:
> On Sunday 30 August 2009, Philip Lowman wrote:
> > On Fri, Aug 28, 2009 at 4:29 AM, Marcel Loose <loose at astron.nl> wrote:
> > > Hi all,
> > >
> > > Up till now I've been using the not officially supported and released
> > > FindPthreads.cmake macro to check for the presence of pthreads. However,
> > > the maintainer of that macro wrote (a comment in Mantis) that he would
> > > drop support for FindPthreads in favor of the more general and
> > > officially supported FindThreads.cmake macro.
> > >
> > > However, I have some difficulty understandig how to properly use
> > > FindThreads.cmake. Contrary to most FindXXX macros it does not set
> > > THREADS_INCLUDE_DIR and THREADS_LIBRARY. It does set some *_INIT
> > > variables, but I thought that *_INIT variables were only used by CMake
> > > itself to preset compiler and linker flags, and that these were not to
> > > be used outside.
> > >
> > > Could someone shed a light on this?
> >
> > I could also use some illumination on this.  I get that you're supposed to
> > use CMAKE_THREAD_LIBS_INIT with target_link_libraries() because libpthread
> > isn't always called "libpthread", but it also looks like
> > CMAKE_THREAD_LIBS_INIT can also be set to "-pthread" in the event the
> > system doesn't have a pthread library and it's supposed to be a compile
> > definition thing...???  If so, why one variable instead of two?  Also what
> > systems does this happen on?
> >
> > I'm not sure if anyone is actually using the pthreads-win32 stuff I wrote
> 
> This one: http://sourceware.org/pthreads-win32/ ?
> 3 years ago I was using it (to make that software easily portable).
> 
> I also think FindThreads.cmake is somewhat strange, doesn't it basically load 
> the thread library of the current platform ? That means that you get 
> different APIs on different platforms and therefor need different code ?
> 
> Alex

It turns out there different versions of the FindPthreads macro lying
around :-(. I was refering to this
http://www.vtk.org/Bug/file_download.php?file_id=2282&type=bug version,
which can be found here http://www.vtk.org/Bug/view.php?id=9074

Best regards,
Marcel Loose.