(_AS_LINENO_WORKS): New macro.

(_AS_LINENO_PREPARE): Use it instead of shell eval, since
eval $LINENO is not portable in practice.

diff --git a/lib/m4sugar/m4sh.m4 b/lib/m4sugar/m4sh.m4
index 4ea6d03659f45ec7abfb30b5d8e8754cb27b0cac..5cb299fb84182e51f8277201a25e40d6bb4aadaf 100644 (file)
--- a/lib/m4sugar/m4sh.m4
+++ b/lib/m4sugar/m4sh.m4
@@ -459,6 +459,17 @@ else
 fi
 ])# _AS_EXPR_PREPARE
 
+# _AS_LINENO_WORKS
+# ---------------
+# Succeed if the currently executing shell supports LINENO.
+m4_define([_AS_LINENO_WORKS],
+[{
+  as_lineno_1=$LINENO
+  as_lineno_2=$LINENO
+  as_lineno_3=`(expr $as_lineno_1 + 1) 2>/dev/null`
+  test "x$as_lineno_1" != "x$as_lineno_2" &&
+  test "x$as_lineno_3"  = "x$as_lineno_2"
+}])
 
 # _AS_LINENO_PREPARE
 # ------------------
@@ -473,16 +484,7 @@ fi
 # it protects us from repetitive rewrites.  Be sure to have a test
 # that does detect non LINENO support...
 m4_define([_AS_LINENO_PREPARE],
-[as_command='
-  as_lineno_1=$LINENO
-  as_lineno_2=$LINENO
-  as_lineno_3=`(expr $as_lineno_1 + 1) 2>/dev/null`
-  test "x$as_lineno_1" != "x$as_lineno_2" &&
-  test "x$as_lineno_3"  = "x$as_lineno_2"
-'
-if eval "$as_command"; then
-  :
-else
+[_AS_LINENO_WORKS || {
   # Find who we are.  Look in the path if we contain no path at all
   # relative or not.
   case $[0] in
@@ -505,7 +507,7 @@ else
       [for as_base in sh bash ksh sh5; do
         case $as_dir in
         /*)
-          if ("$as_dir/$as_base" -c "$as_command") 2>/dev/null; then
+          if ("$as_dir/$as_base" -c '_AS_LINENO_WORKS') 2>/dev/null; then
             CONFIG_SHELL=$as_dir/$as_base
             export CONFIG_SHELL
             exec "$CONFIG_SHELL" "$[0]" ${1+"$[@]"}
@@ -533,7 +535,7 @@ else
   . ./$as_me.lineno
   # Exit status is that of the last command.
   exit
-fi
+}
 ])# _AS_LINENO_PREPARE