Re: [PATCH] A better (?) _AC_EXEEXT

[Akim Demaille]

| It was also mentioned on the list a while ago (by yours truly) how the
| _AC_EXEEXT macro has a circular dependency: _AC_EXEEXT uses
| AC_LINK_IFELSE which uses $ac_exeext which is found by _AC_EXEEXT.

AFAICS you still have this problem: you use AC_LINK_IFELSE.  You
shouldn't, rather, see how AC_OBJEXT uses AC_TRY_EVAL directly, that's
the way to go.

| My new version of the _AC_EXEEXT macro fixes both these problems, with
| a change in behavior: it now just searches (in a prefered order) for a
| valid executable suffix -- instead of trying hard to find _the_
| correct suffix.

The previous code was, apparently, able to cope with other extensions
than `' and `.exe'.  I know of no others, agreed, but we could keep
this part.  I wouldn't struggle though :)

| BTW, is the "-ef" option to ``test'' portable? If not, that part could
| be stripped out.

See the documentation of Autoconf :)

        @item @command{test} (files)
        To enable @code{configure} scripts to support
        cross-compilation, they shouldn't do anything that tests
        features of the build system instead of the host system.  But
        occasionally you may find it necessary to check whether some
        arbitrary file exists.  To do so, use @samp{test -f} or
        @samp{test -r}.  Do not use @samp{test -x}, because
        @sc{4.3bsd} does not have it.  Do not use @samp{test -e}
        either, because Solaris 2.5 does not have it.


| AFAICS, this should also kill the last trace of use of _AC_CYGWIN,
| _AC_MINGW32 and _AC_EMXOS2.

This is good and bad.  I'm in favor of removing these macros, because
people should then depend upon AC_CANONICAL_HOST.  But if some people
think we should keep them, then we should reimplement then on top of
the AC_CANONICAL macros.

Thanks a lot for working on this issue!