Update Xcode version checks

Closes Homebrew/homebrew#11044.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Homebrew/cmd/doctor.rb

@@ -181,41 +181,12 @@ def check_for_broken_symlinks
   end
 end
 
-def check_gcc_42
-  if MacOS.gcc_42_build_version == nil
-    # Don't show this warning on Xcode 4.2+
-    if MacOS.xcode_version < "4.2"
-      "We couldn't detect gcc 4.2.x. Some formulae require this compiler."
-    end
-  elsif MacOS.gcc_42_build_version < RECOMMENDED_GCC_42
-    <<-EOS.undent
-      Your gcc 4.2.x version is older than the recommended version.
-      It may be advisable to upgrade to the latest release of Xcode.
+def check_for_latest_xcode
+  if MacOS.xcode_version.nil? then return <<-EOS.undent
+    We couldn't detect any version of Xcode.
+    If you downloaded Xcode from the App Store, you may need to run the installer.
     EOS
   end
-end
-
-def check_xcode_exists
-  if MacOS.xcode_version == nil
-      <<-EOS.undent
-        We couldn't detect any version of Xcode.
-        If you downloaded Xcode from the App Store, you may need to run the installer.
-      EOS
-  elsif MacOS.xcode_version < "4.0"
-    if MacOS.gcc_40_build_version == nil
-      "We couldn't detect gcc 4.0.x. Some formulae require this compiler."
-    elsif MacOS.gcc_40_build_version < RECOMMENDED_GCC_40
-      <<-EOS.undent
-        Your gcc 4.0.x version is older than the recommended version.
-        It may be advisable to upgrade to the latest release of Xcode.
-      EOS
-    end
-  end
-end
-
-def check_for_latest_xcode
-  # the check_xcode_exists check is enough
-  return if MacOS.xcode_version.nil?
 
   latest_xcode = case MacOS.version
     when 10.5 then "3.1.4"

Library/Homebrew/cmd/install.rb

@@ -34,20 +34,10 @@ module Homebrew extend self
     raise "Cannot write to #{HOMEBREW_PREFIX}" unless HOMEBREW_PREFIX.writable? or HOMEBREW_PREFIX.to_s == '/usr/local'
   end
 
-  def check_cc
-    if MacOS.snow_leopard?
-      if MacOS.llvm_build_version < RECOMMENDED_LLVM
-        opoo "You should upgrade to Xcode 3.2.6"
-      end
-    else
-      if (MacOS.gcc_40_build_version < RECOMMENDED_GCC_40) or (MacOS.gcc_42_build_version < RECOMMENDED_GCC_42)
-        opoo "You should upgrade to Xcode 3.1.4"
-      end
-    end
-  rescue
-    # the reason we don't abort is some formula don't require Xcode
-    # TODO allow formula to declare themselves as "not needing Xcode"
-    opoo "Xcode is not installed! Builds may fail!"
+  def check_xcode
+    require 'cmd/doctor'
+    xcode = Checks.new.check_for_latest_xcode
+    opoo xcode unless xcode.nil?
   end
 
   def check_macports
@@ -70,7 +60,7 @@ module Homebrew extend self
   def perform_preinstall_checks
     check_ppc
     check_writable_install_location
-    check_cc
+    check_xcode
     check_macports
     check_cellar
   end

Library/Homebrew/global.rb

@@ -76,10 +76,6 @@ HOMEBREW_USER_AGENT = "Homebrew #{HOMEBREW_VERSION} (Ruby #{RUBY_VERSION}-#{RUBY
 
 HOMEBREW_CURL_ARGS = '-qf#LA'
 
-RECOMMENDED_LLVM = 2326
-RECOMMENDED_GCC_40 = (MACOS_VERSION >= 10.6) ? 5494 : 5493
-RECOMMENDED_GCC_42 = (MACOS_VERSION >= 10.6) ? 5664 : 5577
-
 require 'fileutils'
 module Homebrew extend self
   include FileUtils