bug in ${##} expansion

bug in ${##} expansion

[Eric Blake]

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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 ${##}'

-- 
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org


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Re: bug in ${##} expansion

[Peter Stephenson]

On Fri, 11 Mar 2011 12:07:20 -0700
Eric Blake <eblake@redhat.com> 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@ntlworld.com>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/

Re: bug in ${##} expansion

[Peter Stephenson]

On Fri, 11 Mar 2011 20:04:37 +0000
Peter Stephenson <p.w.stephenson@ntlworld.com> wrote:
> On Fri, 11 Mar 2011 12:07:20 -0700
> Eric Blake <eblake@redhat.com> 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.

A couple more missing.

Index: Src/subst.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/subst.c,v
retrieving revision 1.118
diff -p -u -r1.118 subst.c
--- Src/subst.c	11 Mar 2011 21:06:00 -0000	1.118
+++ Src/subst.c	21 Mar 2011 10:13:00 -0000
@@ -2039,6 +2039,8 @@ 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 == Quest
+		    || cc == '$' || cc == String || cc == Qstring
 		    || cc == '#' || cc == Pound
 		    || cc == '-' || (cc == ':' && s[2] == '-')
 		    || (isstring(cc) && (s[2] == Inbrace || s[2] == Inpar)))) {

-- 
Peter Stephenson <pws@csr.com>            Software Engineer
Tel: +44 (0)1223 692070                   Cambridge Silicon Radio Limited
Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK


Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom