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

[Douglas C. Schmidt]

Hi Thomas,

   Thanks for using 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].

Right, in general, it's a good idea to include the ACE headers first.

> 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.

That's fine, but I still recommend including the ACE headers first!

Thanks,

        Doug

> 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
> 
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