Pass the version into the Compiler constructor, eliminate a type check

Library/Homebrew/compilers.rb

@@ -1,13 +1,4 @@
-class Compiler < Struct.new(:name, :priority)
+class Compiler < Struct.new(:name, :version, :priority)
-  # The full version of the compiler for comparison purposes.
-  def version
-    if name.is_a? String
-      MacOS.non_apple_gcc_version(name)
-    else
-      MacOS.send("#{name}_build_version")
-    end
-  end
-
   # This is exposed under the `build` name for compatibility, since
   # `fails_with` continues to use `build` in the public API.
   # `build` indicates the build number of an Apple compiler.
@@ -107,16 +98,19 @@ class CompilerSelector
     @f = f
     @compilers = CompilerQueue.new
     %w{clang llvm gcc gcc_4_0}.map(&:to_sym).each do |cc|
-      unless MacOS.send("#{cc}_build_version").nil?
+      version = MacOS.send("#{cc}_build_version")
-        @compilers << Compiler.new(cc, priority_for(cc))
+      unless version.nil?
+        @compilers << Compiler.new(cc, version, priority_for(cc))
       end
     end
 
     # non-Apple GCC 4.x
     SharedEnvExtension::GNU_GCC_VERSIONS.each do |v|
-      unless MacOS.non_apple_gcc_version("gcc-4.#{v}").nil?
+      name = "gcc-4.#{v}"
+      version = MacOS.non_apple_gcc_version(name)
+      unless version.nil?
         # priority is based on version, with newest preferred first
-        @compilers << Compiler.new("gcc-4.#{v}", 1.0 + v/10.0)
+        @compilers << Compiler.new(name, version, 1.0 + v/10.0)
       end
     end
   end