[ace-users] [RFC] #error'ing or #warning when _REENTRANT is not defined

[Thomas Girard]

Hello,

here's the PRF:

    ACE VERSION: 5.5.9
    HOST MACHINE and OPERATING SYSTEM:
      Debian GNU/Linux unstable
    COMPILER NAME AND VERSION (AND PATCHLEVEL):
      g++ (GCC) 4.1.3 20070601 (prerelease) (Debian 4.1.2-12)
    THE $ACE_ROOT/ace/config.h FILE:
      symlink to config-linux.h
    THE $ACE_ROOT/include/makeinclude/platform_macros.GNU FILE:
      symlink to platform_linux.GNU
      
    CONTENTS OF $ACE_ROOT/bin/MakeProjectCreator/config/default.features
      unchanged

    AREA/CLASS/EXAMPLE AFFECTED:
      Depending on #include order, a program behavior can change

    DOES THE PROBLEM AFFECT:
        COMPILATION? yes
        LINKING? no
        EXECUTION? possibly

    SYNOPSIS:
      Including some headers before or after ACE can make programs
behave differently. It does not affect the autotools compilation method.

    DESCRIPTION:
A while ago, the Debian packages for ACE got a bug report showing that
#include'ing a boost header before any ACE header or after did not
behave the same[1].

I worked around this by converting the automatic definition of the
_REENTRANT macro into an #error. (Note that the code has moved to
$ACE_ROOT/ace/config-macros.h recently.)

It turns out it's probably not the way to go, as it breaks very simple
use cases[3].

What would be a better way to address this issue? I think replacing the
#error with a #warning followed by the #define could do.

Regards,

Thomas

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=380739
[2] http://bugs.debian.org/cgi-bin/bugreport.cgi?msg=22;filename=20-check-_REENTRANT.dpatch;att=1;bug=380739
[3] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=420216