zsh compinit breaks with KSH_ARRAYS, KSH_GLOB

[Mikel Ward]

After upgrading to wily, trying to Tab autocomplete prints a bunch of errors.

It seems that

if [[ -z "$skip_global_compinit" ]]; then
  autoload -U compinit
  compinit
fi

in /etc/zsh/zshrc, and the completion rules it loads from /usr/share/zsh/functions/Completion, is incompatible with KSH_ARRAYS and KSH_GLOB, which previously worked fine in vivid.

Repro:
---
sudo useradd -m zshtest
sudo su - zshtest
cat >.zshrc <<EOF
emulate sh
setopt KSH_ARRAYS
setopt KSH_GLOB
EOF

sudo su - zshtest
cd /<TAB>
mikel-study% cd /
_all_labels:63: bad math expression: operator expected at `funcstack ...'
_description:63: bad math expression: operator expected at `comp_ignor...'
_path_files:63: bad math expression: operator expected at `pfx '
_path_files:63: bad math expression: operator expected at `prepaths '
_path_files:63: bad math expression: operator expected at `ignore '
_path_files:63: bad math expression: operator expected at `ignore'
_main_complete:338: bad math expression: operator expected at `lastdescr'
_main_complete:377: bad math expression: operator expected at `comp_color...'
---

Putting skip_global_compinit=1 in ~/.zshenv works around the problem, as does "unsetopt GLOBAL_RCS".

I imagine my set up is unsupported, but I notice that /usr/share/zsh/functions/Completion/compinit at least makes an attempt to avoid this by doing
---
emulate -L zsh
setopt extendedglob
---

One pattern that seems likely to be problematic is the dynamic definition of functions inside other functions, such as _next_tags creating _all_labels inside its body, which presumably uses the current shell options rather than the ones the completions assume are active.

$ dpkg -S /etc/zsh/zshrc /usr/share/zsh/functions/Completion/Base/_next_tags
zsh-common: /etc/zsh/zshrc
zsh-common: /usr/share/zsh/functions/Completion/Base/_next_tags

$ apt-cache show zsh-common
Package: zsh-common
Priority: optional
Section: shells
Installed-Size: 11882
Maintainer: Ubuntu Developers <email address hidden>
Original-Maintainer: Debian Zsh Maintainers <email address hidden>
Architecture: all
Source: zsh
Version: 5.1.1-1ubuntu1

[Mikel Ward (mikelward)]

Oops, my repro left out

sudo chsh -s /bin/zsh zshtest

between lines 1 and 2, and

exit

after "EOF" and before the second "sudo su - zshtest".