Re: [bug-gnulib] poll.h replacement

[Bruno Haible]

Ralf Wildenhues wrote on 2006-03-03:
> the test is fine, but the build fails later:
> 
> |         xlc -DHAVE_CONFIG_H -DEXEEXT=\"\" -DEXEEXT=\"\"  
> -DLIBDIR=\"/usr/local/lib\" -I. -I../../dummy-0/lib -I..    -D_THREAD_SAFE  
> -g -c ../../dummy-0/lib/poll.c
> | "../../dummy-0/lib/poll.c", line 54.1: 1506-343 (S) Redeclaration of 
> rpl_poll differs from previous declaration on line 119 of 
> "/usr/include/sys/poll.h".
> | "../../dummy-0/lib/poll.c", line 54.1: 1506-381 (I) The type "void*" of 
> parameter 1 in the prototype declaration is not compatible with the 
> corresponding parameter type "struct pollfd*" in the nonprototype declaration.
> 
> because /usr/include/poll.h exists and thus the replacement header is
> not added (earlier in gl_FUNC_POLL).  The patch below adds it anyway in
> case we deem poll() inacceptable.

Thanks. I agree with you that AIX should be treated like MacOS X here.
(The bug on MacOS X led to very strange behaviour of GNU clisp on MacOS X
when stdin was redirected from a pipe; similar brokenness would likely
happen on AIX.)

With your patch in, the variable POLL_H is modified 37 lines after it has
already been AC_SUBSTed. To keep the macro maintainable, I rearrange it a bit.

Bruno


2006-04-23  Bruno Haible  <address@hidden>

        * poll.m4 (gl_FUNC_POLL): Rearrange code, so that POLL_H gets
        assigned exactly once.

*** poll.m4.bak 2006-04-24 01:46:18.000000000 +0200
--- poll.m4     2006-04-24 01:57:49.000000000 +0200
***************
*** 8,19 ****
  [
    AC_CHECK_HEADERS(poll.h)
    if test "$ac_cv_header_poll_h" = no; then
!     POLL_H=poll.h
    else
-     POLL_H=
-   fi
-   AC_SUBST([POLL_H])
- 
    AC_CHECK_FUNC(poll,
      [# Check whether poll() works on special files (like /dev/null) and
       # and ttys (like /dev/tty). On MacOS X 10.4.0 and AIX 5.3, it doesn't.
--- 8,15 ----
  [
    AC_CHECK_HEADERS(poll.h)
    if test "$ac_cv_header_poll_h" = no; then
!     gl_cv_func_poll=no
    else
      AC_CHECK_FUNC(poll,
        [# Check whether poll() works on special files (like /dev/null) and
         # and ttys (like /dev/tty). On MacOS X 10.4.0 and AIX 5.3, it doesn't.
***************
*** 53,70 ****
  This is MacOSX or AIX
  #endif
  ], [gl_cv_func_poll=no], [gl_cv_func_poll=yes])])])
    if test $gl_cv_func_poll = yes; then
      AC_DEFINE([HAVE_POLL], 1,
        [Define to 1 if you have the 'poll' function and it works.])
!   fi
! 
!   if test $gl_cv_func_poll = no; then
!     POLL_H=poll.h # Avoid differing declaration from a system header.
      AC_LIBOBJ(poll)
      AC_DEFINE(poll, rpl_poll,
        [Define to poll if the replacement function should be used.])
      gl_PREREQ_POLL
    fi
  ])
  
  # Prerequisites of lib/poll.c.
--- 49,67 ----
  This is MacOSX or AIX
  #endif
  ], [gl_cv_func_poll=no], [gl_cv_func_poll=yes])])])
+   fi
    if test $gl_cv_func_poll = yes; then
+     POLL_H=
      AC_DEFINE([HAVE_POLL], 1,
        [Define to 1 if you have the 'poll' function and it works.])
!   else
!     POLL_H=poll.h
      AC_LIBOBJ(poll)
      AC_DEFINE(poll, rpl_poll,
        [Define to poll if the replacement function should be used.])
      gl_PREREQ_POLL
    fi
+   AC_SUBST([POLL_H])
  ])
  
  # Prerequisites of lib/poll.c.