Keg::MUST_EXIST_DIRECTORIES: Frameworks is for macOS

Library/Homebrew/extend/os/keg.rb

+require "extend/os/mac/keg" if OS.mac?

Library/Homebrew/extend/os/mac/keg.rb

+class Keg
+  GENERIC_KEG_LINK_DIRECTORIES = remove_const :KEG_LINK_DIRECTORIES
+  KEG_LINK_DIRECTORIES = (GENERIC_KEG_LINK_DIRECTORIES + ["Frameworks"]).freeze
+end

Library/Homebrew/keg.rb

@@ -66,7 +66,7 @@ class Keg
   LOCALEDIR_RX = %r{(locale|man)/([a-z]{2}|C|POSIX)(_[A-Z]{2})?(\.[a-zA-Z\-0-9]+(@.+)?)?}
   INFOFILE_RX = %r{info/([^.].*?\.info|dir)$}
   KEG_LINK_DIRECTORIES = %w[
-    bin etc include lib sbin share var Frameworks
+    bin etc include lib sbin share var
   ].freeze
   MUST_EXIST_SUBDIRECTORIES = (
     KEG_LINK_DIRECTORIES - %w[var] + %w[
@@ -672,3 +672,5 @@ class Keg
     end
   end
 end
+
+require "extend/os/keg"