Re: IBM z/OS compatibility issues - pthread

[Daniel Richard G.]

On Sun, 2019 Nov 17 22:18-05:00, Bruno Haible wrote:
>
> > More specifically, to get a suitable pthreads interface, you need to
> > #define _UNIX95_THREADS and _XOPEN_SOURCE=600.
> 
> I'd suggest to add this to the recommended values of CC and CXX in
> https://gitlab.com/ghwiki/gnow-how/wikis/Platforms/Configuration

For archive readers: There is a parallel thread discussing what bits of
system knowledge should go into online docs, and which ones might be
better integrated into the build framework.

> > (This could perhaps be added to AC_USE_SYSTEM_EXTENSIONS for this
> > system.)
>
> I'm not sure adding these flags in AC_USE_SYSTEM_EXTENSIONS or
> gl_USE_SYSTEM_EXTENSIONS would work for all packages. For the
> majority, probably yes, but for all of them? Not sure.

I am wondering how inclusive "all" is meant to be.

One could, in theory, have a package that wants/requires the alternate
form of the pthreads API that z/OS provides. But such a package would
only be usable on z/OS, and that is not a likely design decision for a
GNU project.

Would not most packages be suited by a build environment that provides
the standard pthreads API, as well as others? The above feature macros
are similar in spirit to _ALL_SOURCE / _GNU_SOURCE, in that way (i.e.
"why wouldn't you want this?").

Admittedly, there may be some features that are blocked out by those. If
this is occurring in my Gnulib test runs, and it is not producing an
error/failure (e.g. tests skipped due to missing functionality), then I
am not aware of it. The flags (and bug reports!) I've compiled have been
driven primarily by the desire to allow Gnulib to build everything it
wants to build---which presumably spans a broad enough array of
functionality to cover the needs of most, if not all packages.

> > I would thus suggest adding something like the following to
> > lib/pthread.in.h:
> > 
> >     #if defined(__MVS__) && !defined(PTHREAD_RWLOCK_INITIALIZER)
> >     # define PTHREAD_RWLOCK_INITIALIZER PTHREAD_RWLOCK_INITIALIZER_NP
> >     #endif
> 
> Tell the package maintainers to import the gnulib module 'pthread-
> rwlock'. It will deal with the missing PTHREAD_RWLOCK_INITIALIZER;
> this issue occurs also on some older Solaris versions.

If I omit that fragment, I get this build error:

    source='/tmp/testdir/gltests/test-pthread.c' object='test-pthread.o' 
libtool=no \
    DEPDIR=.deps depmode=aix /bin/sh /tmp/testdir/build-aux/depcomp \
    xlc-wrap -DHAVE_CONFIG_H -DEXEEXT=\"\" -I. -I/tmp/testdir/gltests -I..  
-DGNULIB_STRICT_CHECKING=1 -DIN_GNULIB_TESTS=1 -I. -I/tmp/testdir/gltests -I.. 
-I/tmp/testdir/gltests/.. -I../gllib -I/tmp/testdir/gltests/../gllib 
-D_UNIX95_THREADS -D_XOPEN_SOURCE=600 -DNSIG=39 -qhaltonmsg=CCN3296  -g -q64 
-qfloat=ieee -qlanglvl=extc99 -qenumsize=4  -c -o test-pthread.o 
/tmp/testdir/gltests/test-pthread.c
    ERROR CCN3221 /tmp/testdir/gltests/test-pthread.c:35    Initializer must be 
a valid constant expression.
    WARNING CCN3196 /tmp/testdir/gltests/test-pthread.c:56    Initialization 
between types "void*" and "unsigned long" is not allowed.
    CCN0793(I) Compilation failed for file /tmp/testdir/gltests/test-pthread.c. 
 Object file not created.
    make[4]: *** [test-pthread.o] Error 12

I don't see "PTHREAD_RWLOCK_INITIALIZER_NP" anywhere in a clean Gnulib
tree, so I'm not sure how this could already be addressed...


--Daniel


-- 
Daniel Richard G. || address@hidden
My ASCII-art .sig got a bad case of Times New Roman.