[boost] Re: Problematic inclusion of "pthread.h".

From: Markus Schöpflin (markus.schoepflin_at_[hidden])
Date: 2004-10-05 11:23:46

Jonathan Wakely wrote:

> On Tue, Oct 05, 2004 at 04:28:46PM +0100, John Maddock wrote:
> 
> 
>>>Markus, I believe what you're seeing is the problem that prompted the
>>>GCC developers to unconditionally define _REENTRANT even when -pthread
>>>is not given (and which breaks Boost for GCC 3.4), see
>>>http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11953
>>
>>That's what I thought, but http://tinyurl.com/3lyr8 suggests that 
>>_REENTRANT *is* defined, even without -pthread (unless this is an artifact 
>>of including <iostream>).
> 
> <iostream> includes <ostream> which includes <ios> which includes <iosfwd>
> which includes $platform/bits/c++io.h which includes gthr.h which includes
> gthr-default.h which defines _REENTRANT to 1.

That's what I also discovered.

> Solution: define _REENTRANT before including anything, or include a
> libstdc++ header (which will define _REENTRANT and include pthread.h)

The native compiler (toolset tru64cxx65) doesn't define _REENTRANT and 
things seem to work out correctly.

GCC's include files OTOH unconditionally define _REENTRANT before including 
"pthread.h" which forces boost to also include "pthread.h", if I understand 
things correctly.

But reentrant is not defined at the point where "pthread.h" is included 
which leads to the problem described.

I think I'm missing something here.

Markus