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

From: John Maddock (john_at_[hidden])
Date: 2004-10-05 10:06:44

> When compiling the smart pointer tests with gcc 3.4.2 on Tru64, two tests 
> fail with an error message. (See http://tinyurl.com/4jngu )
>
> As far as I can see, the shared pointer implementation at some point 
> includes the "pthread.h" system header file but gcc on Tru64 requires 
> that -pthread must be specified on the command line when including this 
> header file.
>
> When running this test with gcc 3.4.2 on Linux the file "pthread.h" is 
> also included but gcc doesn't require the addition of -pthread in the 
> command line on this platform.
>
> This leads to the question whether it is ok to include "pthread.h" without 
> specifying -pthread on the command line. Does anyone know an answer to 
> this?

I think on some platforms <pthread.h> doesn't compile unless _REENTRANT or 
some similar compiler-specific magic symbol is defined: in other words it's 
an assert that the compiler is indeed in thread safe mode.

It looks to me as though BOOST_HAS_THREADS is getting set unconditionally 
for gcc on this platform, and presumably we should only set it when 
_REENTRANT is defined (I'm assuming that's the symbol that gets defined when 
the -thread option is used - can you check?).

Hold on... checked the output from config_info and looks as though 
_REENTRANT *is* defined, so I'm mystified.  I also note that the platform is 
detected as "generic unix".  Do you know what macros gcc defines to identify 
this platform?

Thanks,

John.