AC_INIT: quote invalid feature names

Changes:
   configure: error: invalid feature name: debug
to
   configure: error: invalid feature name: `debug '
to make it obvious if trailing space is the reason why a feature
name was rejected; similar to existing error messages elsewhere
about invalid shell variable names.

* lib/autoconf/general.m4 (_AC_INIT_PARSE_ENABLE2): Add quotes.
Reported by Noel Grandin.

Signed-off-by: Eric Blake <eblake@redhat.com>

diff --git a/lib/autoconf/general.m4 b/lib/autoconf/general.m4
index e2e9b6a7879d13435ad490f364a6eab8bbd55249..696a9a1a6e43a095d90069ce77eafab232d5e5c4 100644 (file)
--- a/lib/autoconf/general.m4
+++ b/lib/autoconf/general.m4
@@ -998,8 +998,8 @@ m4_define([_AC_INIT_PARSE_ENABLE2],
     ac_useropt=`expr "x$ac_option" : 'x-*$1-\(m4_if([$1], [$2], [[[^=]]], [.])*\)'`
     # Reject names that are not valid shell variable names.
     expr "x$ac_useropt" : "[.*[^-+._$as_cr_alnum]]" >/dev/null &&
-      AC_MSG_ERROR(
-       [invalid ]m4_if([$2], [with], [package], [feature])[ name: $ac_useropt])
+      AC_MSG_ERROR([invalid ]m4_if([$2], [with],
+        [package], [feature])[ name: `$ac_useropt'])
     ac_useropt_orig=$ac_useropt
     ac_useropt=`AS_ECHO(["$ac_useropt"]) | sed 's/[[-+.]]/_/g'`
     case $ac_user_opts in