Subject: Re: [PATCH v5 (for maint)] git-completion: fix regression in zsh support

From: Jonathan Nieder <[email-masked]>
Date: Tue, 10 May 2011 17:16:00 -0500

Felipe Contreras wrote:

> Right now zsh is quite broken; the completion doesn't notice when
> there's a subcommand. For example: "git log origi<TAB>" gives no
> completions because it would try to find a "git origi..." command. The
> issue would be gone in zsh 4.3.12, but for now we can workaround it by
> porting the same fix.
>
> The problem started after commit v1.7.4-rc0~11^2~2 (bash: get
> --pretty=m<tab> completion to work with bash v4), which introduced
> _get_comp_words_by_ref() that comes from bash-completion[1] scripts, and
> relies on the 'words' variable. However, it turns out 'words' is a

The _get_comp_words_by_ref function does not rely on but writes to the
'words' variable.  Aside from that, this is a nicer summary.

> special variable used by zsh completion. From zshcompwid(1):
[...]
> [2] http://zsh.git.sourceforge.net/git/gitweb.cgi?p=zsh/zsh;a=commitdiff;h=e880604f029088f32fb1ecc39213d720ae526aaa

I doubt this URL will last forever.  Why not just say commit
e880604f029088f32fb1ecc, or '"29140: hide the "words" special variable
so that it may be used as an ordinary variable by bash completions",
2011-05-04' which conveniently includes a mailing list reference?

Thanks for the fix and your patience with me.  To answer the sincere
questions I could find among your replies to v4:

 - I included the "completion: move private shopt shim for zsh to
   __git_ namespace" patch in the series as a reminder to Junio,
   since he had requested one.

 - "in no part of [compgen] does the zsh emulation make use of the
   'words' special variable" is just plain false.  compgen -F uses the
   'words' variable, and we are lucky to have not needed to use it
   yet.

 - I changed the comment because when I read the original, putting
   myself in the shoes of someone who didn't know the context, I found
   it confusing.  "work around bug in old versions of zsh" just leaves
   me wondering "What bug?  Is it a bug in the behavior of 'local',
   and are we working around it by using an alternate spelling?"  

   That said, I suppose the main point of a comment is to say
   "something important happens here", and a person can use 

	git log -S"workaround zsh's bug" -- contrib/completion/git-completion.bash

   to find out what exactly it is, so no harm done.