feat(bun): add plugin (#11859)

plugins/bun/README.md

@@ -0,0 +1,20 @@
+# Bun Plugin
+
+This plugin sets up completion for [Bun](https://bun.sh).
+
+To use it, add `bun` to the plugins array in your zshrc file:
+
+```zsh
+plugins=(... bun)
+```
+
+This plugin does not add any aliases.
+
+## Cache
+
+This plugin caches the completion script and is automatically updated when the
+plugin is loaded, which is usually when you start up a new terminal emulator.
+
+The cache is stored at:
+
+- `$ZSH_CACHE_DIR/completions/_bun_` completions script

plugins/bun/bun.plugin.zsh

@@ -0,0 +1,14 @@
+# If Bun is not found, don't do the rest of the script
+if (( ! $+commands[bun] )); then
+  return
+fi
+
+# If the completion file doesn't exist yet, we need to autoload it and
+# bind it to `bun`. Otherwise, compinit will have already done that.
+if [[ ! -f "$ZSH_CACHE_DIR/completions/_bun" ]]; then
+  typeset -g -A _comps
+  autoload -Uz _bun
+  _comps[bun]=_bun
+fi
+
+bun completions >| "$ZSH_CACHE_DIR/completions/_bun" &|