Allow opting out of ZSH completions for Git

[seivan]

This commit removed the ability to opt out.

This issue shows that this is inherently a degrading experience for the user. Some of the examples are posted here that documents some of the differences between the two approaches.

There was an attempt to completely remove the official ZSH completions that was shut down on the premise So long as upstream are providing it: we'll be shipping it, sorry.

However, this causes some issues

Forcing the git completions on users, will degrade the experience. How much depends on what you expect, there has been some hyperbole, but in the end there is a degradation in user experience.
There is no way out of it since the way fpath is setup, site-functions takes precedence.

/usr/local/share/zsh/site-functions
/usr/local/Cellar/zsh/5.8_1/share/zsh/functions

1. git <tab> don't show aliases.
2. Don't properly work with other zsh plugins using git.
3. Documentation on arguments are omitted.
   And so on.

Again, this is forced on a user, when installing git from Homebrew.

One solution is for a manual removal of the symlink /usr/local/share/zsh/site-functions/{_git, git-completion.bash}, but that's not a good approach as brew upgrade will add them again.
Another solution is to opt out of all Homebrew completions, this isn't a viable solution as most are actually useful and it's good to offer a nice out of the box experience.

There was PR that added the ability to opt out, but it was shut down in 2018.
Can there be a new discussions to revive that, and allow users to opt out using without-completion

[carlocab]

Does prepending to fpath not work?

[seivan]

I am not sure what issues that will cause, so far I haven't touched or modified my fpath personally, maybe OMZ or Zinit is doing so.
But I rather not modify my fpath and cause more issues down the line, if the alternative can be just opting out of git ZSH completion, which has been a point of discussion.

[h3xOo]

Homebrew prepends its zsh completion to the fpath, overwriting default zsh git completion. I hacked it by moving first entry of fpath at the end, right after evaling Homebrew setup.

Here's the code I'm left with:

eval "$(/opt/homebrew/bin/brew shellenv)"
# Move prepended Homebrew's fpath to the end.
fpath=(${fpath[@]:1} $fpath[1])

[CFD2]

what a legend, thank you!

It is a bit hard to believe nobody has done anything about it in so long

[rhcarvalho]

For future reference, I went with a more explicit take by removing the path by name:

if [[ -f "/opt/homebrew/bin/brew" ]]; then
  eval "$(/opt/homebrew/bin/brew shellenv)"
fi

# Remove the Homebrew completions that the above `brew shellenv` prepends to
# fpath, so that we can prefer system-level completions. In particular, the git
# completions that come with zsh are much better than the ones provided by the
# Homebrew formula, see https://github.com/orgs/Homebrew/discussions/2797.
fpath=("${fpath[@]:#/opt/homebrew/share/zsh/site-functions}")
# Now add the Homebrew site-functions back to the END of the list.
fpath+=(/opt/homebrew/share/zsh/site-functions(N-/))