Avoid walking the entire PATH when looking for a better shell.

* lib/m4sugar/m4sh.m4 (_AS_SHELL_SANITIZE): Test shell characteristics
as the PATH is walked.

diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4
index 3eac1a8752f10811376abc47ca29c6b23f2dd606..141658764a96ff2b9d2ab7c3c35f56f9def7376c 100644 (file)
--- a/lib/m4sugar/m4sh.m4
+++ b/lib/m4sugar/m4sh.m4
@@ -221,24 +221,23 @@ dnl Remove any tests from suggested that are also required
        [as_have_required=no])
   AS_IF([test x$as_have_required = xyes && _AS_RUN(["$as_suggested"])],
     [],
-    [as_candidate_shells=
-    _AS_PATH_WALK([/bin$PATH_SEPARATOR/usr/bin$PATH_SEPARATOR$PATH],
+    [_AS_PATH_WALK([/bin$PATH_SEPARATOR/usr/bin$PATH_SEPARATOR$PATH],
       [case $as_dir in @%:@(
         /*)
           for as_base in sh bash ksh sh5; do
-            as_candidate_shells="$as_candidate_shells $as_dir/$as_base"
+            # Try only shells that exist, to save several forks.
+            as_shell=$as_dir/$as_base
+            AS_IF([{ test -f "$as_shell" || test -f "$as_shell.exe"; } &&
+                   _AS_RUN(["$as_required"], ["$as_shell"])],
+                  [CONFIG_SHELL=$as_shell as_have_required=yes
+                  m4_set_empty([_AS_DETECT_SUGGESTED_BODY], [break 2],
+                    [AS_IF([_AS_RUN(["$as_suggested"], ["$as_shell"])],
+                           [break 2])])])
           done;;
-       esac])
-
-      for as_shell in $as_candidate_shells $SHELL; do
-        # Try only shells that exist, to save several forks.
-        AS_IF([{ test -f "$as_shell" || test -f "$as_shell.exe"; } &&
-               _AS_RUN(["$as_required"], ["$as_shell"])],
-              [CONFIG_SHELL=$as_shell
-              as_have_required=yes
-              m4_set_empty([_AS_DETECT_SUGGESTED_BODY], [break],
-                [AS_IF([_AS_RUN(["$as_suggested"], ["$as_shell"])], [break])])])
-      done
+       esac],
+      [AS_IF([{ test -f "$SHELL" || test -f "$SHELL.exe"; } &&
+             _AS_RUN(["$as_required"], ["$SHELL"])],
+            [CONFIG_SHELL=$SHELL as_have_required=yes])])
 
       AS_IF([test "x$CONFIG_SHELL" != x],
        [# We cannot yet assume a decent shell, so we have to provide a