[BuildTools] An upcoming glpk glitch

[Andreas Waechter]

Hi Lou,

> 	While working on OsiGlpk, I noticed that glpk has changed the way it
> defines symbols.  Glpk defines aliases in its include files.  As of 4.13, it
> used
>
> #define lpx_simplex           glp_lpx_simplex
>
> As of 4.15, it uses
>
> #define lpx_simplex           _glp_lpx_simplex
>
> Note the leading underscore. Also, the organisation of the .h files has changed.
> I haven't pulled 4.14 to pinpoint the change.
>
> 	The immediate challenge on the buildtools side is that we'll probably
> need to cope with both versions for a while.  The immediate workaround (for
> those who can't rebuild configure files locally) is the existing
> --disable-*-libcheck hook.  Longer term, there are a couple of options:
>
>  1) Extend COIN_HAS_USER_LIBRARY so that it accepts a list of symbols, and
>     considers the check successful if any one of them succeeds.
>
>  2) Extend COIN_HAS_USER_LIBRARY so that it #includes the .h file supplied as
>     the third parameter when it makes the link check for the fourth parameter.
>
>  3) Some combination of the above.
>
>  4) Do something in individual configure.ac files (not preferable, in my view).

In principle, I have no concerns about this, except of course that the new 
version will work :)  When I did the original version, I implemented a 
very simple version, and it would be great to make it more powerful.

> Looking at COIN_HAS_USER_LIBRARY, we might also want to begin the conversion
> from AC_TRY_LINK (now deprecated) to AC_LINK_IFELSE.

Good point.

> 	Either of 1) or 2) will solve the problem for glpk.  Option 2) might
> protect us into the future, but actually using an include file in the link test
> has its own hazards.  Upgrading to AC_LINK_IFELSE offers the opportunity for
> some language independence, by way of using AC_LANG_PROGRAM.
>
> 	I'll add something to the BuildTools tickets and Known Issues pages.
> But I wanted to get this out to the list to see if people have opinions about
> which direction to pursue, or cautions from previous experience.

Before submitting anything to the BuildTools/trunk, please get in touch 
with me, because I'm trying to get a new release out soon...  (yes, Laci, 
I have been promising that for a while... and I'm testing!)

Cheers,

Andreas