Index: configure.ac
===================================================================
RCS file: /sources/quilt/quilt/configure.ac,v
retrieving revision 1.72
diff -u -u -r1.72 configure.ac
--- configure.ac	1 Feb 2006 15:18:10 -0000	1.72
+++ configure.ac	2 Feb 2006 06:36:05 -0000
@@ -172,7 +172,6 @@
 $PACKAGE_NAME needs it.  If you have access to a version of awk
 which does understand such constructs, you can supply its path
 with the '--with-awk=' option.
-Solaris users can use /usr/xpg4/bin/awk.
 ])
 fi
 
@@ -220,9 +219,33 @@
 QUILT_COMPAT_PROG_PATH(DIFF, diff)
 QUILT_COMPAT_PROG_PATH(PATCH, patch)
 
+# Sun diff and others will not work, and feature does are pointless.
+AC_MSG_CHECKING([the version of $DIFF])
+if $DIFF --version 2>/dev/null | grep GNU >/dev/null; then
+  set -- `$DIFF --version 2>/dev/null | cut -d ' ' -f 6`
+  diff_version=$1
+  AC_MSG_RESULT($diff_version)
+  saved_IFS=$IFS; IFS='.'
+  set -- $diff_version
+  IFS=$saved_IFS
+  set -- `echo $1 | $TR -cd 0-9` `echo $2 | $TR -cd 0-9`
+  if test 0$1 -lt 2 || test 0$1 -eq 2 -a 0$2 -lt 4 ; then
+    diff_version=
+  fi
+else
+  AC_MSG_RESULT(no GNU diff)
+fi
+if test -z "$diff_version" ; then
+  AC_MSG_ERROR([
+$PACKAGE_NAME requires at least version 2.7 of GNU diffutils. You can
+download a current version of patch from ftp.gnu.org, or if you already
+have GNU diff then you can supply its path with the '--with-diff=' option.
+])
+fi
+
 # Sun's patch, and others, do not work because GNU patch options are used.
 AC_MSG_CHECKING([the version of $PATCH])
-if $PATCH --version 2> /dev/null | grep -q GNU ; then
+if $PATCH --version 2> /dev/null | grep GNU >/dev/null; then
   set -- `$PATCH --version 2> /dev/null`
   patch_version=$2
   AC_MSG_RESULT($patch_version)