Re: bug in ${##} expansion

[Peter Stephenson <p.w.stephenson@xxxxxxxxxxxx>]

On Fri, 11 Mar 2011 12:07:20 -0700
Eric Blake <eblake@xxxxxxxxxx> wrote:
> POSIX requires ${#parameter} to expand to the length of parameter as a
> string.  It also requires that ${parameter#word} substitution have a
> word (that is, ${parameter#} with a missing word is a zsh extension).
> 
> Therefore, this should output 2, not 11:
> 
> zsh -c 'set 1 2 3 4 5 6 7 8 9 10 11; echo ${##}'

It's a straightforward bug, not specific to POSIX compatibility in
this case; testing for a name after the # is a special case which
covered some special names but not others.

Index: Src/subst.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/subst.c,v
retrieving revision 1.117
diff -p -u -r1.117 subst.c
--- Src/subst.c	11 Mar 2011 16:32:11 -0000	1.117
+++ Src/subst.c	11 Mar 2011 19:59:57 -0000
@@ -2039,6 +2039,7 @@ paramsubst(LinkList l, LinkNode n, char 
 	} else if ((c == '#' || c == Pound) &&
 		   (itype_end(s+1, IIDENT, 0) != s + 1
 		    || (cc = s[1]) == '*' || cc == Star || cc == '@'
+		    || cc == '#' || cc == Pound
 		    || cc == '-' || (cc == ':' && s[2] == '-')
 		    || (isstring(cc) && (s[2] == Inbrace || s[2] == Inpar)))) {
 	    getlen = 1 + whichlen, s++;
Index: Test/D04parameter.ztst
===================================================================
RCS file: /cvsroot/zsh/zsh/Test/D04parameter.ztst,v
retrieving revision 1.54
diff -p -u -r1.54 D04parameter.ztst
--- Test/D04parameter.ztst	18 Jan 2011 10:29:58 -0000	1.54
+++ Test/D04parameter.ztst	11 Mar 2011 19:59:57 -0000
@@ -175,6 +175,14 @@
 0:${#...}, $#...
 >8 8 8 8 8 8 8 8
 
+  set 1 2 3 4 5 6 7 8 9
+  print ${##}
+  set 1 2 3 4 5 6 7 8 9 10
+  print ${##}
+0:${##} is length of $#
+>1
+>2
+
   array=(once bitten twice shy)
   print IF${array}THEN
   print IF${^array}THEN

-- 
Peter Stephenson <p.w.stephenson@xxxxxxxxxxxx>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/