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Re: svn commit: r1182984 - /subversion/trunk/subversion/tests/libsvn_subr/cache-test.c

From: Daniel Shahaf <d.s_at_daniel.shahaf.name>
Date: Thu, 13 Oct 2011 20:02:30 +0200

Philip Martin wrote on Thu, Oct 13, 2011 at 18:44:44 +0100:
> Daniel Shahaf <d.s_at_daniel.shahaf.name> writes:
>
> > First of all, I made the same patch yesterday elsewhere.
>
> Another bug :)
>
> > Second of all, the use is #if, not #ifdef, so I believe the macro is
> > always defined (to 0 or 1).
>
> The one doesn't follow from the other. In either case the macro could
> be zero, non-zero, no value or not defined:
>
> #if #ifdef
> #define APR_HAS_THREADS 1 true true
> #define APR_HAS_THREADS 0 false true
> #define APR_HAS_THREADS true true
> <nothing> false false
>

Is this standard behaviour?

> So not defining APR_HAS_THREADS is a valid way to define no thread
> support, but it means you can't use APR_HAS_THREADS directly as a
> variable.
>
> It's possible that APR will always ensure that APR_HAS_THREADS is either
> 0 or 1, but the C language does not.
>

My reading of
http://svn.apache.org/repos/asf/apr/apr/tags/0.9.0/include/apr.h.in
http://svn.apache.org/repos/asf/apr/apr/tags/0.9.0/include/apr.hnw
http://svn.apache.org/repos/asf/apr/apr/tags/0.9.0/include/apr.hw
is that APR_HAS_THREADS is always defined.

> --
> uberSVN: Apache Subversion Made Easy
> http://www.uberSVN.com
Received on 2011-10-13 20:03:19 CEST

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