Subject: Re: Advanced option parsing across zsh commands
From: Bart Schaefer <[email-masked]>
To: Zsh hackers list <[email-masked]>
Date: Tue, 26 Jan 2016 22:56:09 -0800
List-Id: Zsh Workers List <zsh-workers.zsh.org>

On Jan 26,  7:59pm, Sebastian Gniazdowski wrote:
} Subject: Re: Advanced option parsing across zsh commands
}
} > zparseopts also doesn't handle "negated options" in the +X format
} 
} This sounded like if there would a workaround for +X. I tried the
} following: define option "+", which takes argument. Then replace "+X"
} with "-+X" in the command line. However:
} 
} % zparseopts -A opts -D -E b: c +:

That does not define an option "+" which takes an argument.  That in
fact defines an option (empty string) which may be repeated multiple
times and takes an argument, because the "+" invokes the NAME+ form
of option description.

There's not a lot of internal consistency checking in zparseopts.  Old
code that has not been reviewed since it was written.

To define an option named "+" instead of an option named "", you are
intended to use:

    zparseopts -A opts -D -E b: c '\+:'

However, because of a bug, you can't actually do that.  The backslash
causes everything after it to shift one character to the left, but
the NUL-terminator is not also shifted, so the above accidentally
defines the option "++" instead of the option "+".

torch% typeset -A opts
torch% set -- a -b something -++X -- -c
torch% zparseopts -A opts -D -E b: c \\+:
torch% print -lr -- $@
a
--
-c
torch% print -r -- ${(kv)opts}
-b something -++ X
torch% 

With the patch below, the very first character of the option spec is
always taken to be part of the option name (unless that first char is
is a backslash, in which case it is shifted off as usual).  So you
no longer need to escape a "+" (though it doesn't hurt to do so):

torch% typeset -A opts
torch% set -- a -b something -+X -- -c
torch% zparseopts -A opts -D -E b: c +:  
torch% print -r -- ${(kv)opts}         
-b something -+ X

And using "++" does the expected thing:

torch% typeset -A opts=()                     
torch% set -- a -b something -+X -+Y -+Z -- -c
torch% zparseopts -A opts -D -E b: c ++:      
torch% print -r -- ${(kv)opts}                
-b something -+ XYZ
torch% 

For pre-5.3 zsh I suggest you use a different character than "+" for
your proposed workaround, e.g.

    set -- a -b something -\*X -\*Y -\*Z -- -c
    zparseopts -A opts -D -E b: c '*+:'

should work.

diff --git a/Src/Modules/zutil.c b/Src/Modules/zutil.c
index d98028a..12a4c03 100644
--- a/Src/Modules/zutil.c
+++ b/Src/Modules/zutil.c
@@ -1745,13 +1745,15 @@ bin_zparseopts(char *nam, char **args, UNUSED(Options ops), UNUSED(int func))
 	for (p = o; *p; p++) {
 	    if (*p == '\\' && p[1])
 		p++;
-	    else if (*p == '+') {
-		f |= ZOF_MULT;
-		*p = '\0';
-		p++;
-		break;
-	    } else if (*p == ':' || *p == '=')
-		break;
+	    else if (p > o) {	/* At least one character of option name */
+		if (*p == '+') {
+		    f |= ZOF_MULT;
+		    *p = '\0';
+		    p++;
+		    break;
+		} else if (*p == ':' || *p == '=')
+		    break;
+	    }
 	}
 	if (*p == ':') {
 	    f |= ZOF_ARG;
@@ -1789,6 +1791,7 @@ bin_zparseopts(char *nam, char **args, UNUSED(Options ops), UNUSED(int func))
 		p++;
 	    *n++ = *p;
 	}
+	*n = '\0';
 	if (get_opt_desc(o)) {
 	    zwarnnam(nam, "option defined more than once: %s", o);
 	    return 1;