patchGNU Autoconf Archive - Patches: patch #7666, ax_pthread macro fails for C++ on...


patch #7666: ax_pthread macro fails for C++ on Solaris

Submitter:  None
Submitted:  Thu 17 Nov 2011 12:57:22 AM UTC
Priority:  5 - Normal Status:  Done
Assigned to:  simons Originator Email:  -email is unavailable-
Open/Closed:  Closed
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Mon 05 Dec 2011 11:50:18 PM UTC, comment #9: 

Solaris is SunOS 5, so no, it's not a SunOS 4 thing, and I doubt threading was the same going back that far (and I think we can safely consider that going back farther than necessary).

I have not personally had any problems putting it only in PTHREAD_CFLAGS, but I may have thought libtool included CFLAGS in that link step.

-- Scott

Fri 02 Dec 2011 08:17:07 PM UTC, comment #8: 

My concern is the redundancy of specifying -D_REENTRANT with cc+"-mt" or gcc+"-pthreads", as well as cc+"-lpthread", and the lack of "-mt" in PTHREAD_LIBS.

There is this note in the macro:

  # On Solaris (at least, for some versions), libc contains stubbed
  # (non-functional) versions of the pthreads routines, so link-based
  # tests will erroneously succeed. [...] So,
  # we'll just look for -pthreads and -lpthread first:

Does anyone here know what versions of Solaris this applies to? Is this a SunOS4 thing?

Daniel Richard G. <iskunk>
Fri 02 Dec 2011 03:32:37 PM UTC, comment #7: 

I've used the patch for years in my software packages without any trouble, but I would say the only possible improvement is detecting that it's "that" compiler on Solaris. I don't know what the convention is for that or if you have one. Maybe just checking for "CC" is enough. I use the "if gcc" check because I haven't encountered anything there but gcc and Sun's.

-- Scott Cantor

Fri 02 Dec 2011 03:15:44 PM UTC, comment #6: 

I'm wondering about the state of this patch, because I'd like to release a new version of the archive soon. Is that change to AX_PTHREAD considered all right the way it is, or does anyone object?

Peter Simons <simons>
Group administrator
Tue 22 Nov 2011 01:08:46 AM UTC, comment #5: 

Sounds about right. From the (Solaris 8) CC(1) man page...

  -mt       Compile and link for multithreaded code.

            This option:

            o Passes -D_REENTRANT to the preprocessor

            o Passes -lthread in the correct order to ld

            o Ensures that, for standard mode (the default
              mode), libthread is linked before libCrun

            o Ensures that, for compability mode (-compat),
              libthread is linked before libC

            The -mt option is required if the application or
            libraries are multithreaded.


            You must use this option, rather than -lthread.

            If you are using POSIX threads, you must link with
            the options -mt -lpthread.  The -mt option is
            necessary because libC (compatibility mode) and
            libCrun (standard mode) need libthread for a mul-
            tithreaded application.

Daniel Richard G. <iskunk>
Tue 22 Nov 2011 12:22:48 AM UTC, comment #4: 

Usually omitting -mt doesn't matter that much for C applications, but it triggers different startup code for C++ applications that ensures the right ordering of static constructors and so forth in conjunction with the threading routines.

If you have a preferred test for which compiler is involved, that's fine, as long as -mt is added for Solaris Studio.

Mon 21 Nov 2011 11:33:57 PM UTC, comment #3: 

> What does PTHREAD_CFLAGS and PTHREAD_LIBS return without this patch?

On both a 64-bit Solaris 8 system, and a 64-bit/AMD64 Solaris 10 system here:

    PTHREAD_CC = cc
    PTHREAD_LIBS = -lpthread

But then, things aren't as simple as they seem. From the cc(1) man page:

 -mt  Passes D_REENTRANT to preprocessor.  Appends  -lthread.
      If  you are doing your own multithread coding, you must
      use this option in the  compile  and  link  steps.   To
      obtain  faster  execution,  this option requires a mul-
      tiprocessor system. On a single-processor  system,  the
      resulting executable usually runs more slowly with this

So potentially, for the Solaris compiler, -D_REENTRANT is redundant and -mt is also needed in PTHREAD_LIBS...

Daniel Richard G. <iskunk>
Mon 21 Nov 2011 10:52:23 PM UTC, comment #2: 

Pushed to the Git repository in commit 6c8eddf2606e768cea66e49fc746330ba88de18e. Thank you very much!

Peter Simons <simons>
Group administrator
Mon 21 Nov 2011 06:35:21 PM UTC, comment #1: 

Thank you very much for pointing out that problem. If you have the chance, could you please attach a proper diff/patch file to this bug report to fix the problem?

Peter Simons <simons>
Group administrator
Thu 17 Nov 2011 12:57:22 AM UTC, original submission:  

The section that adds "extra" flags for Solaris is missing the addition of the -mt option for Oracle/Sun CC. It's used at the top in the detection code, but never gets added. _RENTRANT alone is not sufficient when using that compiler with C++, you get improper safety for object startup and shutdown.

I use this in place of the existing code for special flags:

            if test "$GCC" = "yes"; then
                flag="-mt -D_REENTRANT"



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Attach Files:

Attached Files
file #24417:  axthreadpatch.txt added by None (715B - text/plain - My working patch is attached.)


Depends on the following items: None found

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Carbon-Copy List
  • -email is unavailable- added by iskunk (Posted a comment)
  • -email is unavailable- added by simons (Posted a comment)
  • -email is unavailable- added by simons
  • -email is unavailable- added by simons
  • -email is unavailable- added by None (Submitted the item)

    Follow 8 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2011-12-21 simons StatusReady For Test Done
        Open/ClosedOpen Closed
    2011-11-21 simons StatusNeed Info Ready For Test
    2011-11-21 None Attached File- Added axthreadpatch.txt, #24417
    2011-11-21 simons StatusNone Need Info
        Assigned toNone simons
        Carbon-Copy- Added steven g. johnson <>
        Carbon-Copy- Added daniel richard g. <>

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