Archiving git branches as tags

I have a spicy git alias that allows me to "archive" old git branches by converting them to tags, making them less visible across git tooling.

# ~/.gitconfig
[alias]
archive-branch = "!f() { \
    : git switch; \
    local git_branch=${1:-$(git branch --show-current)}; \
    git co main && \
      git tag archive/$git_branch && \
      git branch -D $git_branch; \
  }; f"

The magic of this alias is that aside from tagging and deleting the branch as desired, it also adds support for shell completion so I can tab complete the branch I want to archive (if not the current branch I'm on).

This is accomplished by the strange magic of wrapping the alias in an immediately executed bash function (!f() { ... }; f) and having the first line be : git switch. git switch isn't actually run; it's a hint to git to use the same completion for this alias as git switch (via and source).

Important note: the strange magic requires the official git completion script. zsh comes with its own git completion which does not support specifying the completion style, so you'll also have to make sure zsh loads the official completion. On macOS, if using the Xcode Developer Tools version of git, you can link it into /usr/local/share/zsh/site-functions like so:

sudo mkdir -p /usr/local/share/zsh/site-functions
sudo ln -s /Applications/Xcode.app/Contents/Developer/usr/share/git-core/git-completion.zsh \
  /usr/local/share/zsh/site-functions/_git

And then adding the following to .zshrc, because git-completion.zsh relies on git-completion.bash.

# ~/.zshrc
# you may already have this line
autoload -Uz compinit && compinit

zstyle ':completion:*:*:git:*' script /Applications/Xcode.app/Contents/Developer/usr/share/git-core/git-completion.bash

Credit for original idea goes to this reddit thread.