Re: Fix AC_FUNC_ERROR_AT_LINE and others

[Paul Eggert]

Ralf Wildenhues <address@hidden> writes:

> -[AC_LIBSOURCES([error.h, error.c])dnl
> +[AC_CHECK_HEADERS_ONCE(error.h)
> +AC_LIBSOURCES([error.h, error.c])dnl
>  AC_CACHE_CHECK([for error_at_line], ac_cv_lib_error_at_line,
> -[AC_LINK_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT],
> -                              [error_at_line (0, 0, "", 0, "");])],
> +[AC_LINK_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT
> +                               #ifdef HAVE_ERROR_H
> +                               # include <error.h>
> +                               #endif],

Thanks, but it's simpler just to include <error.h> without testing for it.
That should work on all modern hosts.

> -   address@hidden:@include <stdio.h>], [return !fseeko;])
> +   address@hidden:@include <stdio.h>], [typedef int (*fp) ();
> +                          fp p = (fp) fseeko;
> +                          return !p;])

How about if we just call fseeko as a function, and use it in parentheses
(to avoid macros, which was part of the point.)?  The patch below does that.

> +[AC_REQUIRE([AC_GNU_SOURCE])dnl

I think you are right, it's better to use AC_USE_SYSTEM_EXTENSIONS hee.

Thanks.  I installed this revised patch.

2006-09-26  Paul Eggert  <address@hidden>

        * lib/autoconf/functions.m4 (AC_FUNC_FSEEKO): Don't compile the
        fseeko testing program twice; just use the earlier result.
        * lib/autoconf/specific.m4 (_AC_SYS_LARGEFILE_MACRO_VALUE):
        Set cache var to 'unknown' (not 'no') if leaving the macro unset
        still doesn't let the program compile.
        (AC_SYS_LARGEFILE): Test for _LARGE_FILES only if earlier tests
        failed.

        * lib/autoconf/functions.m4: Fix problems reported by Ralf Wildenhues.
        (AC_FUNC_ERROR_AT_LINE): Don't bother to check for error.h.  Just
        include it, without including anything else.
        (AC_FUNC_FSEEKO): Avoid gcc -Wall warnings about constant
        expressions.
        (AC_FUNC_STRNLEN): Require AC_USE_SYSTEM_EXTENSIONS.

2006-09-26  Ralf Wildenhues  <address@hidden>

        * lib/autoconf/functions.m4 (AC_FUNC_ERROR_AT_LINE): Check for
        `error.h', and include it, for a `error_at_line' prototype.
        Use a nonempty format string in the link test.
        * lib/autoconf/functions.m4 (AC_FUNC_WAIT3): Include <sys/wait.h>,
        for a declaration of wait3.

Index: lib/autoconf/functions.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/functions.m4,v
retrieving revision 1.110
diff -p -u -r1.110 functions.m4
--- lib/autoconf/functions.m4   25 Sep 2006 17:50:06 -0000      1.110
+++ lib/autoconf/functions.m4   26 Sep 2006 20:53:23 -0000
@@ -472,8 +472,8 @@ AN_FUNCTION([error_at_line], [AC_FUNC_ER
 AC_DEFUN([AC_FUNC_ERROR_AT_LINE],
 [AC_LIBSOURCES([error.h, error.c])dnl
 AC_CACHE_CHECK([for error_at_line], ac_cv_lib_error_at_line,
-[AC_LINK_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT],
-                                [error_at_line (0, 0, "", 0, "");])],
+[AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <error.h>],
+                                [error_at_line (0, 0, "", 0, "an error 
occurred");])],
                [ac_cv_lib_error_at_line=yes],
                [ac_cv_lib_error_at_line=no])])
 if test $ac_cv_lib_error_at_line = no; then
@@ -589,17 +589,13 @@ AC_DEFUN([AC_FUNC_FSEEKO],
 [_AC_SYS_LARGEFILE_MACRO_VALUE(_LARGEFILE_SOURCE, 1,
    [ac_cv_sys_largefile_source],
    [Define to 1 to make fseeko visible on some hosts (e.g. glibc 2.2).],
-   address@hidden:@include <stdio.h>], [return !fseeko;])
+   address@hidden:@include <stdio.h>],
+   [[return fseeko (stdin, 0, 0) && (fseeko) (stdin, 0, 0);]])
 
 # We used to try defining _XOPEN_SOURCE=500 too, to work around a bug
 # in glibc 2.1.3, but that breaks too many other things.
 # If you want fseeko and ftello with glibc, upgrade to a fixed glibc.
-AC_CACHE_CHECK([for fseeko], [ac_cv_func_fseeko],
-[AC_LINK_IFELSE([AC_LANG_PROGRAM(address@hidden:@include <stdio.h>],
-                                [[return fseeko && fseeko (stdin, 0, 0);]])],
-               [ac_cv_func_fseeko=yes],
-               [ac_cv_func_fseeko=no])])
-if test $ac_cv_func_fseeko = yes; then
+if test $ac_cv_sys_largefile_source != unknown; then
   AC_DEFINE(HAVE_FSEEKO, 1,
     [Define to 1 if fseeko (and presumably ftello) exists and is declared.])
 fi
@@ -1653,7 +1649,8 @@ LIBS="-lintl $LIBS"])])dnl
 # ---------------
 AN_FUNCTION([strnlen], [AC_FUNC_STRNLEN])
 AC_DEFUN([AC_FUNC_STRNLEN],
-[AC_CACHE_CHECK([for working strnlen], ac_cv_func_strnlen_working,
+[AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])dnl
+AC_CACHE_CHECK([for working strnlen], ac_cv_func_strnlen_working,
 [AC_RUN_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT], [[
 #define S "foobar"
 #define S_LEN (sizeof S - 1)
@@ -1998,6 +1995,7 @@ AC_CACHE_CHECK([for wait3 that fills in 
 [AC_INCLUDES_DEFAULT[
 #include <sys/time.h>
 #include <sys/resource.h>
+#include <sys/wait.h>
 /* HP-UX has wait3 but does not fill in rusage at all.  */
 int
 main ()
Index: lib/autoconf/specific.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/autoconf/specific.m4,v
retrieving revision 1.370
diff -p -u -r1.370 specific.m4
--- lib/autoconf/specific.m4    15 Aug 2006 16:24:42 -0000      1.370
+++ lib/autoconf/specific.m4    26 Sep 2006 20:53:23 -0000
@@ -130,17 +130,18 @@ m4_define([_AC_SYS_LARGEFILE_TEST_INCLUD
 m4_define([_AC_SYS_LARGEFILE_MACRO_VALUE],
 [AC_CACHE_CHECK([for $1 value needed for large files], [$3],
 [while :; do
-  $3=no
   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([$5], [$6])],
-                   [break])
+                   [$3=no; break])
   AC_COMPILE_IFELSE([AC_LANG_PROGRAM(address@hidden:@define $1 $2
 $5], [$6])],
                    [$3=$2; break])
+  $3=unknown
   break
 done])
-if test "$$3" != no; then
-  AC_DEFINE_UNQUOTED([$1], [$$3], [$4])
-fi
+case $$3 in #(
+  no | unknown) ;;
+  *) AC_DEFINE_UNQUOTED([$1], [$$3], [$4]);;
+esac
 rm -f conftest*[]dnl
 ])# _AC_SYS_LARGEFILE_MACRO_VALUE
 
@@ -181,10 +182,12 @@ if test "$enable_largefile" != no; then
     ac_cv_sys_file_offset_bits,
     [Number of bits in a file offset, on hosts where this is settable.],
     [_AC_SYS_LARGEFILE_TEST_INCLUDES])
-  _AC_SYS_LARGEFILE_MACRO_VALUE(_LARGE_FILES, 1,
-    ac_cv_sys_large_files,
-    [Define for large files, on AIX-style hosts.],
-    [_AC_SYS_LARGEFILE_TEST_INCLUDES])
+  if test $ac_cv_sys_file_offset_bits = unknown; then
+    _AC_SYS_LARGEFILE_MACRO_VALUE(_LARGE_FILES, 1,
+      ac_cv_sys_large_files,
+      [Define for large files, on AIX-style hosts.],
+      [_AC_SYS_LARGEFILE_TEST_INCLUDES])
+  fi
 fi
 ])# AC_SYS_LARGEFILE