[CLN-list] CLN defines macro As in global space

[Bruno Haible]

Hi Sebastian,

> We, developers of the model checker Storm, are long-time users of CLN. Thanks for all your work.
> We recently got a bug message that boils down to a conflict between different libraries. 
> 
> In particular, CLN adds the Macro AS in include/cln/number.h in line 274. This macro is globally defined upon including CLN and uses conflicts, e.g., MLPACK. 
> While we can work around this issue, we thought it may be possible to rename the macro to CL_AS or even _CL_AS. 

This would be problematic, because the 'As' macro is a documented (and important)
functionality of CLN. For 'The', there is 'cln::the' as a template alternative,
but for 'As' we don't have an alternative 'cln::as' yet.

Is the problem really so big? In https://github.com/mlpack/mlpack the only uses
of the identifier 'As' are not in front of an opening parenthesis:
  mlpack/src/mlpack/methods/lsh/lsh_search_impl.hpp:671:      std::vector<bool> As = Ai;
  mlpack/src/mlpack/methods/lsh/lsh_search_impl.hpp:674:      if (PerturbationShift(As) && PerturbationValid(As))
  mlpack/src/mlpack/methods/lsh/lsh_search_impl.hpp:676:        perturbationSets.push_back(As); // add shifted set to sets
  mlpack/src/mlpack/methods/lsh/lsh_search_impl.hpp:678:            std::make_pair(PerturbationScore(As, scores),
therefore in fact I cannot see a conflict with mlpack at all.

I would therefore suggest the usual workaround:
  - tweak the order of #includes,
  - '#undef As' at appropriate places.

Bruno