+ # 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=$DEFAULT_AUTOCONF_MINVERSION
+ fi
+ case "$autoconf_minversion" in
+ 1.* | 2.[0-4]* | 2.5[0-8]*)
+ func_fatal_error "minimum supported autoconf version is 2.59. Try adding AC_PREREQ([$DEFAULT_AUTOCONF_MINVERSION]) to your configure.ac." ;;
+ esac
+