[GHC] #9283: bad autoconf variable names

[GHC]

#9283: bad autoconf variable names
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       Reporter:  rwbarton          |             Owner:
           Type:  bug               |            Status:  new
       Priority:  low               |         Milestone:
      Component:  libraries/base    |           Version:  7.9
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 {{{
 if test "$ac_cv_header_sys_epoll_h" = yes -a "$ac_cv_func_epoll_ctl" =
 yes; then
   AC_DEFINE([HAVE_EPOLL], [1], [Define if you have epoll support.])
 fi

 if test "$ac_cv_header_sys_event_h" = yes -a "$ac_cv_func_kqueue" = yes;
 then
   AC_DEFINE([HAVE_KQUEUE], [1], [Define if you have kqueue support.])

   AC_CHECK_SIZEOF([kev.filter], [], [#include <sys/event.h>
 struct kevent kev;])

   AC_CHECK_SIZEOF([kev.flags], [], [#include <sys/event.h>
 struct kevent kev;])
 fi

 if test "$ac_cv_header_poll_h" = yes -a "$ac_cv_func_poll" = yes; then
   AC_DEFINE([HAVE_POLL], [1], [Define if you have poll support.])
 fi
 }}}

 The `AC_DEFINE` lines for `HAVE_KQUEUE` and `HAVE_POLL` don't do anything,
 because earlier we have

 {{{
 AC_CHECK_FUNCS([epoll_ctl eventfd kevent kevent64 kqueue poll])
 }}}

 and that already defines `HAVE_KQUEUE` (and sets `ac_cv_func_kqueue`) when
 the `kqueue` function is found.

 Not entirely sure what the right thing to do is here, do we rely on having
 a prototype for `kqueue` in `sys/event.h` specifically? Technically that
 wouldn't be what we check for even if we used a renamed `HAVE_KQUEUE`
 variable.

 AFAIK this doesn't cause any real problems except that it really confused
 me when I tried to simulate not having `poll` by moving
 `/usr/include/poll.h` away temporarily.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9283>
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