feat(brew): add support for custom `BREW_LOCATION`

Fixes #11888

Co-authored-by: Matt Cable <github@curiousstranger.org>

plugins/brew/README.md

@@ -10,10 +10,12 @@ plugins=(... brew)
 
 ## Shellenv
 
-If `brew` is not found in the PATH, this plugin will attempt to find it in common
-locations, and execute `brew shellenv` to set the environment appropriately.
-This plugin will also export `HOMEBREW_PREFIX="$(brew --prefix)"` if not previously
-defined for convenience.
+If `brew` is not found in the PATH, this plugin will attempt to find it in common locations, and execute
+`brew shellenv` to set the environment appropriately. This plugin will also export
+`HOMEBREW_PREFIX="$(brew --prefix)"` if not previously defined for convenience.
+
+In case you installed `brew` in a non-common location, you can still set `BREW_LOCATION` variable pointing to
+the `brew` binary before sourcing `oh-my-zsh.sh` and it'll set up the environment.
 
 ## Aliases
 
@@ -33,9 +35,9 @@ defined for convenience.
 
 ## Completion
 
-This plugin configures paths with Homebrew's completion functions automatically, so you don't need to do it manually. See: https://docs.brew.sh/Shell-Completion#configuring-completions-in-zsh.
+This plugin configures paths with Homebrew's completion functions automatically, so you don't need to do it
+manually. See: https://docs.brew.sh/Shell-Completion#configuring-completions-in-zsh.
 
-With the release of Homebrew 1.0, they decided to bundle the zsh completion as part of the
-brew installation, so we no longer ship it with the brew plugin; now it only has brew
-aliases. If you find that brew completion no longer works, make sure you have your Homebrew
-installation fully up to date.
+With the release of Homebrew 1.0, they decided to bundle the zsh completion as part of the brew installation,
+so we no longer ship it with the brew plugin; now it only has brew aliases. If you find that brew completion
+no longer works, make sure you have your Homebrew installation fully up to date.

plugins/brew/brew.plugin.zsh

@@ -1,5 +1,10 @@
 if (( ! $+commands[brew] )); then
-  if [[ -x /opt/homebrew/bin/brew ]]; then
+  if [[ -n "$BREW_LOCATION" ]]; then
+    if [[ ! -x "$BREW_LOCATION" ]]; then
+      echo "[oh-my-zsh] $BREW_LOCATION is not executable"
+      return
+    fi
+  elif [[ -x /opt/homebrew/bin/brew ]]; then
     BREW_LOCATION="/opt/homebrew/bin/brew"
   elif [[ -x /usr/local/bin/brew ]]; then
     BREW_LOCATION="/usr/local/bin/brew"