postinstall: Use CLI::Parser to parse args

Library/Homebrew/cmd/postinstall.rb

@@ -3,11 +3,27 @@
 
 require "sandbox"
 require "formula_installer"
+require "cli_parser"
 
 module Homebrew
   module_function
 
+  def postinstall_args
+    Homebrew::CLI::Parser.new do
+      usage_banner <<~EOS
+        `postinstall` <formula>
+
+        Rerun the post-install steps for <formula>.
+      EOS
+      switch :verbose
+      switch :force
+      switch :debug
+    end
+  end
+
   def postinstall
+    postinstall_args.parse
+
     ARGV.resolved_formulae.each do |f|
       ohai "Postinstalling #{f}"
       fi = FormulaInstaller.new(f)