cvs commit: fptools/libraries/base/Text/Regex Posix.hsc

[Malcolm Wallace]

Ross Paterson <ross at soi.city.ac.uk> writes:

> >   Modified files:
> >     libraries/base/Text/Regex Posix.hsc 
> >   Log:
> >   Fix regex.h include stuff; Ross and Malcolm might want to look at the
> >   new comment
> 
> The "hacky solution" is the only way offered by the FFI spec to specify
> the include for foreign imports.  I gave up on that limitation some
> time ago, and made the Hugs build system extract the -#include options
> from GHC OPTIONS pragmas.  I think it would be better to have a less
> compiler-specific equivalent, though.  An INCLUDE pragma?

The "correct" solution, blessed by the FFI addendum, is for all
such platform-specific configuration to be done outside Haskell,
incorporated into a single .h file that is named in the foreign import.

For instance, here for regexes, the simplest solution is to prepend
to libraries/base/include/regex/regex.h the following few lines:

    #ifdef __GLASGOW_HASKELL__
    #include "ghcconfig.h"
    #endif

    #if HAVE_REGEX_H && HAVE_REGCOMP
    #include <regex.h>
    #define _REGEX_H_

... and then a simple
    foreign import ccall unsafe "regex/regex.h regexec" :: ....
is correct for all environments.

Regards,
    Malcolm