development_tools: add installed? method. (#455)

1 files changed, 9 insertions, 0 deletions

diff --git a/Library/Homebrew/extend/os/mac/development_tools.rb b/Library/Homebrew/extend/os/mac/development_tools.rb
index b80be4c81..1afab513b 100644
--- a/Library/Homebrew/extend/os/mac/development_tools.rb
+++ b/Library/Homebrew/extend/os/mac/development_tools.rb
@@ -1,3 +1,5 @@
+require "os/mac/xcode"
+
 # @private
 class DevelopmentTools
   class << self
@@ -13,6 +15,13 @@ class DevelopmentTools
       end
     end
 
+    # Checks if the user has any developer tools installed, either via Xcode
+    # or the CLT. Convenient for guarding against formula builds when building
+    # is impossible.
+    def installed?
+      MacOS::Xcode.installed? || MacOS::CLT.installed?
+    end
+
     def default_compiler
       case default_cc
       # if GCC 4.2 is installed, e.g. via Tigerbrew, prefer it