Zsh completion defaults crash

Question

$ zsh -f
$ autoload -U compinit
$ compinit
$ zstyle ':completion:*' matcher-list 'm:{a-z}={A-Z}'
now here's the problem:
$ defaults read com.apple.S<tab> offers a number of completions, but
$ defaults read com.apple.s<tab> crashes the shell.
apparently case-insensitive matching can't coexist with the partial-completion matching used in the _defaults function (removing the latter solved the problem). so i'm wondering if my mac just isn't powerful enough to handle this or (if other people can reproduce this) it's a _defaults function bug.
zsh 4.2.6

Answer 1

It seems the problem can be reproduced (on MacOSX and Linux) by the following procedure:
Create a file _mycmd in $HOME/.zsh/functions/ (or anywhere in your FPATH) with the following contents:
#compdef mycmd
_mydomains() {
local -a list
local expl
list=( a.b.Cx a.b.cy a.b.cz )
_wanted domains expl domain compadd -M 'r:|.=* r:|=*' -a list
_arguments '*:domains:_mydomains'
and start a new zsh
% zsh -f
zsh% FPATH=$HOME/.zsh/fuctions:$FPATH
zsh% autoload -U compinit; compinit
zsh% zstyle ':completion:*' matcher-list 'm:{a-z}={A-Z}'
zsh% mycmd a.b.c<TAB>
If you hit <TAB>, zsh hangs and eventually core dumps after few seconds (or minutes). This happens on (at least) Tiger, Leopard and Linux (Fefora7).
As ra5ul writes, the core dump does not occur
if "zstyle ':completion:*' matcher-list 'm:{a-z}={A-Z}'" is not run, or
if "-M 'r:|.=* r:|=*'" is omitted from _mycmd, or
if the value of "list" is changed to either of
list=( a.b.Cx a.b.cy )
list=( a.b.cx a.b.cy a.b.cz )
list=( b.Cx b.cy b.cz )
I have posted a bug report to zsh-workers mailing list.