[doogie@brainfood.com: Bug#163237: zsh barfs on valid shell]

[doogie@brainfood.com: Bug#163237: zsh barfs on valid shell]

[Clint Adams]

This happens under emulate -R sh as well.

----- Forwarded message from Adam Heath <doogie@brainfood.com> -----

adam@yakko:~$ for shell in ash bash zsh ksh; do echo -n "$shell:"; $shell -c 'case foo in (foo)echo foo;;(bar)echo bar;;esac';done
ash:foo
bash:foo
zsh:zsh: parse error near `foo'
ksh:foo
adam@yakko:~$ for shell in ash bash zsh ksh; do echo -n "$shell:"; $shell -c 'case foo in (foo) echo foo;;(bar) echo bar;;esac';done
ash:foo
bash:foo
zsh:foo
ksh:foo

http://www.opengroup.org/onlinepubs/007904975/utilities/xcu_chap02.html#tag_02_10_02

Scroll down a bit to the actual grammer(surrounded by <pre>):

The case_item and case_item_ns show that there is no required space(or other
break char) between the ')' and the compound_list.

case_item_ns     :     pattern ')'               linebreak
                 |     pattern ')' compound_list linebreak
                 | '(' pattern ')'               linebreak
                 | '(' pattern ')' compound_list linebreak
                 ;
case_item        :     pattern ')' linebreak     DSEMI linebreak
                 |     pattern ')' compound_list DSEMI linebreak
                 | '(' pattern ')' linebreak     DSEMI linebreak
                 | '(' pattern ')' compound_list DSEMI linebreak



----- End forwarded message -----

PATCH Re: [doogie@brainfood.com: Bug#163237: zsh barfs on valid shell]

[Bart Schaefer]

On Oct 3,  4:43pm, Clint Adams wrote:
} Subject: [doogie@brainfood.com: Bug#163237: zsh barfs on valid shell]
}
} This happens under emulate -R sh as well.
} 
} ----- Forwarded message from Adam Heath <doogie@brainfood.com> -----
} 
} case foo in (foo)echo foo;;(bar)echo bar;;esac
} zsh:zsh: parse error near `foo'

This is because "(foo)echo" is being parsed as a file pattern [equivalent
to "(foo|foo)echo" for those who don't immediately see why it's being
parsed that way].  The syntax error thus is that there is no close paren
after the pattern -- e.g. zsh is trying to parse one of

  case_item_ns     :     pattern ')' compound_list linebreak
  case_item        :     pattern ')' compound_list DSEMI linebreak

and therefore fails.

This is an inherent ambiguity in using parens for pattern grouping and is
going to have to stay the way it is when not in emulation mode.

Fortunately the emulation fix is not as difficult as I feared it would be.

Index: Src/lex.c
===================================================================
diff -c -r1.7 lex.c
--- Src/lex.c	1 Sep 2002 16:47:38 -0000	1.7
+++ Src/lex.c	4 Oct 2002 03:45:30 -0000
@@ -993,8 +993,12 @@
 	    c = Outbrack;
 	    break;
 	case LX2_INPAR:
-	    if ((sub || in_brace_param) && isset(SHGLOB))
-		break;
+	    if (isset(SHGLOB)) {
+		if (sub || in_brace_param)
+		    break;
+		if (incasepat && !len)
+		    return INPAR;
+	    }
 	    if (!in_brace_param) {
 		if (!sub) {
 		    e = hgetc();
Index: Src/parse.c
===================================================================
diff -c -r1.14 parse.c
--- Src/parse.c	12 Sep 2002 07:59:07 -0000	1.14
+++ Src/parse.c	4 Oct 2002 03:53:08 -0000
@@ -1042,6 +1042,8 @@
 	    yylex();
 	if (tok == OUTBRACE)
 	    break;
+	if (tok == INPAR)
+	    yylex();
 	if (tok != STRING)
 	    YYERRORV(oecused);
 	if (!strcmp(tokstr, "esac"))

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net   

Re: PATCH Re: [doogie@brainfood.com: Bug#163237: zsh barfs on valid shell]

[Peter Stephenson]

"Bart Schaefer" wrote:
> On Oct 3,  4:43pm, Clint Adams wrote:
> } Subject: [doogie@brainfood.com: Bug#163237: zsh barfs on valid shell]
> }
> } This happens under emulate -R sh as well.
> } 
> } ----- Forwarded message from Adam Heath <doogie@brainfood.com> -----
> } 
> } case foo in (foo)echo foo;;(bar)echo bar;;esac
> } zsh:zsh: parse error near `foo'
> 
> This is because "(foo)echo" is being parsed as a file pattern [equivalent
> to "(foo|foo)echo" for those who don't immediately see why it's being
> parsed that way].
> 
> This is an inherent ambiguity in using parens for pattern grouping and is
> going to have to stay the way it is when not in emulation mode.

An option `case_balance_parens' would be a possibility.  The reasoning
for this would be (1) balancing the parentheses is neater anyway, so
having a test to force better syntax is useful (2) inside $(...),
balancing is essential, so using the option makes it consistent.  It
couldn't be on by default, though, so you wouldn't get it with `emulate
zsh', which makes it less useful.

The SH_GLOB test is definitely better for Bourne-style use.

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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