Re: Solving the config.h nightmare ?

[Russ Allbery]

Ralf Wildenhues <address@hidden> writes:
> * Russ Allbery wrote on Sun, Apr 23, 2006 at 03:58:52AM CEST:

>> Even your stripped-down version should rename the defines, since they
>> may otherwise conflict with other Autoconf-using software.  (Yes,
>> usually they will end up with the same values, but not always.)

> Oh, the ones that can conflict should not appear in the installed header
> _at all_, but rather be recomputed by the Autoconf macro that goes along
> with the package, to use by the client package.  (At least for the
> generic ones I'd recommend that; for the other ones renaming is fine.)

Hm... I'm not sure that's a good idea.

Once you've compiled a library, the Autoconf results are now part of the
ABI, particularly such things as the size of data types.  If something
changes on the system to change the Autoconf results and a package
recomputes those values with different results, but you don't recompile
the library, you now get ABI breakage and bus errors and segfaults galore.

I'm much more comfortable with fixing such things in stone at the time of
the library build, and only recomputing them when you rebuild the library.

-- 
Russ Allbery (address@hidden)             <http://www.eyrie.org/~eagle/>