command-not-found module: add support for homebrew >= 4.6.12

As of Homebrew 4.6.12, command-not-found is built into Homebrew core and
the tap is deprecated, causing Homebrew to print deprecation warnings on
init until the tap is uninstalled, after which prezto can't find the
helper in its new location.

* Added logic to look first in the new location for handler.sh in the
  core Homebrew repository, *then* check in Taps.
* Added an OSTYPE check for MacOS to prevent this from accidentally
  engaging on Linux systems using Homebrew as a third party package
  manager

modules/command-not-found/README.md

@@ -6,18 +6,26 @@ install command.
 
 Debian and Arch Linux based distributions use the [`command-not-found`][1] tool.
 
-macOS uses Homebrew's [`command-not-found` clone][2]. Note that unless you have
-a recent version of Homebrew installed, you might also need to tap the
-`command-not-found` Homebrew repository [following the instructions][3].
+macOS uses Homebrew's [`command-not-found` clone][2]. This module will
+automatically load it without needing to manually source `handler.sh` from
+`.zshrc` per the [instructions][3].
+
+Note: Prior to [Homebrew 4.6.12][4], you may have also needed to tap the
+[`command-not-found` Homebrew repository][5]. This will still work as a
+fallback when the `command-not-found` handler can't be detected in Homebrew
+core, but the repository has been deprecated and may print a warning. After
+upgrading Homebrew, it can be untapped.
 
 ## Authors
 
-_The authors of this module should be contacted via the [issue tracker][4]._
+_The authors of this module should be contacted via the [issue tracker][6]._
 
 - [Joseph Booker](https://github.com/sargas)
 - [Indrajit Raychaudhuri](https://github.com/indrajitr)
 
 [1]: https://code.launchpad.net/command-not-found
-[2]: https://github.com/Homebrew/homebrew-command-not-found
-[3]: https://github.com/Homebrew/homebrew-command-not-found#install
-[4]: https://github.com/sorin-ionescu/prezto/issues
+[2]: https://docs.brew.sh/Command-Not-Found
+[3]: https://docs.brew.sh/Command-Not-Found#install
+[4]: https://github.com/Homebrew/brew/releases/tag/4.6.12
+[5]: https://github.com/Homebrew/homebrew-command-not-found
+[6]: https://github.com/sorin-ionescu/prezto/issues

modules/command-not-found/init.zsh

@@ -12,11 +12,22 @@ if [[ -s /etc/zsh_command_not_found ]]; then
 # Load command-not-found on Arch Linux-based distributions.
 elif [[ -s /usr/share/doc/pkgfile/command-not-found.zsh ]]; then
   source /usr/share/doc/pkgfile/command-not-found.zsh
-# Load command-not-found on macOS when Homebrew tap is configured.
-elif (( $+commands[brew] )) \
-      && [[ -s ${hb_cnf_handler::="${HOMEBREW_REPOSITORY:-$commands[brew]:A:h:h}/Library/Taps/homebrew/homebrew-command-not-found/handler.sh"} ]]; then
-  source "$hb_cnf_handler"
-  unset hb_cnf_handler
+# Load command-not-found on macOS when Homebrew is present. Check explicitly
+# for MacOS, since homebrew can be installed on Linux as a supplementary PM
+elif [[ "$OSTYPE" =~ ^darwin ]] && (( $+commands[brew] )); then
+  homebrew_repo=${HOMEBREW_REPOSITORY:-$commands[brew]:A:h:h/Library}
+  # Look for handler in Homebrew core (as of >=4.6.12), then in Taps (< 4.6.12)
+  for hb_cnf_handler in "$homebrew_repo"/{Homebrew/command-not-found/handler.sh,Taps/homebrew/homebrew-command-not-found/handler.sh}; do
+    if [ -f "$hb_cnf_handler" ]; then
+      source "$hb_cnf_handler"
+      unset hb_cnf_handler homebrew_repo
+      break
+    fi
+  done
+  if [ -n "$hb_cnf_handler" ]; then
+    unset hb_cnf_handler homebrew_repo
+    return 1
+  fi
 # Return if requirements are not found.
 else
   return 1