gnulib-tool: looking for minimum autoconf version

[Bruno Haible]

Hi,

The determination of the minimum autoconf version from configure.ac that
I put in did not work well. I'm changing it.

2006-07-29  Bruno Haible  <address@hidden>

        * gnulib-tool (autoconf_minversion): If a --dir option is given and
        relevant, look for configure.ac there, not in the current directory.
        Also use a simple search for AC_PREREQ, not "autoconf --trace".

*** gnulib-tool.bak     2006-07-30 01:14:26.000000000 +0200
--- gnulib-tool 2006-07-30 02:13:28.000000000 +0200
***************
*** 282,288 ****
    lgpl=
    libtool=
    macro_prefix=
-   autoconf_minversion=
    do_changelog=:
    doit=:
    local_gnulib_dir=
--- 282,287 ----
***************
*** 482,489 ****
    # Determine the minimum supported autoconf version from the project's
    # configure.ac.
    DEFAULT_AUTOCONF_MINVERSION="2.59"
!   if test -f configure.ac; then
!     autoconf_minversion=`$AUTOCONF --trace=AC_PREREQ:'$1' | $SORT -g | uniq | 
tail -1`
    fi
    if test -z "$autoconf_minversion"; then
      autoconf_minversion=$DEFAULT_AUTOCONF_MINVERSION
--- 481,523 ----
    # Determine the minimum supported autoconf version from the project's
    # configure.ac.
    DEFAULT_AUTOCONF_MINVERSION="2.59"
!   autoconf_minversion=
!   configure_ac=
!   if { test "$mode" = import || test "$mode" = update; } && test -n 
"$destdir"; then
!     if test -f "$destdir"/configure.ac; then
!       configure_ac="$destdir/configure.ac"
!     else
!       if test -f "$destdir"/configure.in; then
!         configure_ac="$destdir/configure.in"
!       fi
!     fi
!   else
!     if test -f configure.ac; then
!       configure_ac="configure.ac"
!     else
!       if test -f configure.in; then
!         configure_ac="configure.in"
!       fi
!     fi
!   fi
!   if test -n "$configure_ac"; then
!     # Use sed, not autoconf --trace, to look for the AC_PREREQ invocation,
!     # because when some m4 files are omitted from a CVS repository,
!     # "autoconf --trace=AC_PREREQ" fails with an error message like this:
!     #   m4: aclocal.m4:851: Cannot open m4/absolute-header.m4: No such file 
or directory
!     #   autom4te: m4 failed with exit status: 1
!     prereqs=
!     my_sed_traces='
!       s,#.*$,,
!       s,^dnl .*$,,
!       s, dnl .*$,,
!       /AC_PREREQ/ {
!         s,^.*AC_PREREQ([[ ]*\([^])]*\).*$,prereqs="$prereqs \1",p
!       }'
!     eval `sed -n -e "$my_sed_traces" < "$configure_ac"`
!     if test -n "$prereqs"; then
!       autoconf_minversion=`for version in $prereqs; do echo $version; done | 
$SORT -g | uniq | tail -1`
!     fi
    fi
    if test -z "$autoconf_minversion"; then
      autoconf_minversion=$DEFAULT_AUTOCONF_MINVERSION