Implement fails_with for non-Apple compilers

This adds support for non-Apple GCC compilers in the fails_with code.
A fails_with block for a non-Apple compiler looks like:

fails_with :gcc => '4.8.1' do
  cause 'Foo'
end

Non-Apple compilers don't have build numbers, so compiler failures are
based on version strings instead.

Internally non-Apple compilers can be distinguished because they are
passed around as strings instead of symbols.

In addition, this alters the priority list for compilers, with the
following changes:

* Apple GCC 4.2 and LLVM-GCC swap positions, with GCC now taking
  priority. (Maybe LLVM-GCC should just go away.)
* Non-Apple GCC compilers are ranked below GCC 4.2 but above LLVM-GCC
  and Apple GCC 4.0.

1 files changed, 27 insertions, 5 deletions

diff --git a/Library/Homebrew/compilers.rb b/Library/Homebrew/compilers.rb
index 3aaaecbc8..8eb6d56fb 100644
--- a/Library/Homebrew/compilers.rb
+++ b/Library/Homebrew/compilers.rb
@@ -2,16 +2,28 @@ class Compiler < Struct.new(:name, :priority)
   def build
     MacOS.send("#{name}_build_version")
   end
+
+  def version
+    MacOS.non_apple_gcc_version(name) if name.is_a? String
+  end
 end
 
 class CompilerFailure
-  attr_reader :compiler
+  attr_reader :compiler, :version
   attr_rw :build, :cause
 
   def initialize compiler, &block
-    @compiler = compiler
+    # Non-Apple compilers are in the format fails_with compiler => version
+    if compiler.is_a? Hash
+      # currently the only compiler for this case is GCC
+      _, @version = compiler.shift
+      @compiler = 'gcc-' + @version.match(/(\d\.\d)/)[0]
+    else
+      @compiler = compiler
+    end
+
     instance_eval(&block) if block_given?
-    @build = (@build || 9999).to_i
+    @build = (@build || 9999).to_i unless compiler.is_a? Hash
   end
 end
 
@@ -43,6 +55,14 @@ class CompilerSelector
         @compilers << Compiler.new(cc, 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?
+        # priority is based on version, with newest preferred first
+        @compilers << Compiler.new("gcc-4.#{v}", 1.0 + v/10.0)
+      end
+    end
   end
 
   # Attempts to select an appropriate alternate compiler, but
@@ -64,9 +84,11 @@ class CompilerSelector
   def priority_for(cc)
     case cc
     when :clang then MacOS.clang_build_version >= 318 ? 3 : 0.5
-    when :llvm  then 2
-    when :gcc   then 1
+    when :gcc   then 2
+    when :llvm  then 1
     when :gcc_4_0 then 0.25
+    # non-Apple gcc compilers
+    else 1.5
     end
   end
 end