fyi: yet another LINENO bug, this time with Bash

[Paul Eggert]

I just installed the following patch to work around a problem that I
just discovered with Bash 2.05 and LINENO.  I'll also send a bug
report to the Bash maintainers.

Perhaps my optimism about LINENO was not well-founded....

2001-10-31  Paul Eggert  <address@hidden>

        * lib/m4sugar/m4sh.m4 (_AS_LINENO_WORKS): Do not surround body
        with {}, as that triggers a bug in Bash 2.05.

Index: lib/m4sugar/m4sh.m4
===================================================================
RCS file: /cvsroot/autoconf/autoconf/lib/m4sugar/m4sh.m4,v
retrieving revision 1.68
diff -p -u -r1.68 m4sh.m4
--- lib/m4sugar/m4sh.m4 2001/10/31 19:23:37     1.68
+++ lib/m4sugar/m4sh.m4 2001/10/31 20:03:06
@@ -462,14 +462,18 @@ fi
 # _AS_LINENO_WORKS
 # ---------------
 # Succeed if the currently executing shell supports LINENO.
+# This macro does not expand to a single shell command, so be careful
+# when using it.  Surrounding the body of this macro with {} would
+# cause "bash -c '_ASLINENO_WORKS'" to fail (with Bash 2.05, anyway),
+# but that bug is irrelevant to our use of 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$as_lineno_2"
-}])
+  test "x$as_lineno_3"  = "x$as_lineno_2" dnl
+])
 
 # _AS_LINENO_PREPARE
 # ------------------