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.

7 files changed, 103 insertions, 14 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
diff --git a/Library/Homebrew/extend/ENV/std.rb b/Library/Homebrew/extend/ENV/std.rb
index 67ab85952..e931b33ba 100644
--- a/Library/Homebrew/extend/ENV/std.rb
+++ b/Library/Homebrew/extend/ENV/std.rb
@@ -167,6 +167,16 @@ module Stdenv
   end
   alias_method :gcc_4_2, :gcc
 
+  GNU_GCC_VERSIONS.each do |n|
+    define_method(:"gcc-4.#{n}") do
+      gcc = "gcc-4.#{n}"
+      self.cc = self['OBJC'] = gcc
+      self.cxx = self['OBJCXX'] = gcc.gsub('c', '+')
+      set_cpu_cflags
+      @compiler = gcc
+    end
+  end
+
   def llvm
     self.cc  = MacOS.locate("llvm-gcc")
     self.cxx = MacOS.locate("llvm-g++")
diff --git a/Library/Homebrew/extend/ENV/super.rb b/Library/Homebrew/extend/ENV/super.rb
index 2b3957209..9ca88750c 100644
--- a/Library/Homebrew/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/ENV/super.rb
@@ -266,6 +266,13 @@ module Superenv
     self.cc  = self['HOMEBREW_CC'] = "clang"
     self.cxx = "clang++"
   end
+  GNU_GCC_VERSIONS.each do |n|
+    define_method(:"gcc-4.#{n}") do
+      gcc = "gcc-4.#{n}"
+      self.cc = self['HOMEBREW_CC'] = gcc
+      self.cxx = gcc.gsub('c', '+')
+    end
+  end
   def make_jobs
     self['MAKEFLAGS'] =~ /-\w*j(\d)+/
     [$1.to_i, 1].max
diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index bbcb1dab2..29e87af06 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -212,7 +212,12 @@ class Formula
   def fails_with? cc
     cc = Compiler.new(cc) unless cc.is_a? Compiler
     (self.class.cc_failures || []).any? do |failure|
-      failure.compiler == cc.name && failure.build >= cc.build
+      if cc.version
+        # non-Apple GCCs don't have builds, just version numbers
+        failure.compiler == cc.name && failure.version >= cc.version
+      else
+        failure.compiler == cc.name && failure.build >= cc.build
+      end
     end
   end
 
diff --git a/Library/Homebrew/macos.rb b/Library/Homebrew/macos.rb
index 8e379ad2a..de109ade3 100644
--- a/Library/Homebrew/macos.rb
+++ b/Library/Homebrew/macos.rb
@@ -151,6 +151,16 @@ module MacOS extend self
       end
   end
 
+  def non_apple_gcc_version(cc)
+    return unless path = locate(cc)
+
+    ivar = "@#{cc.gsub(/(-|\.)/, '')}_version"
+    return instance_variable_get(ivar) if instance_variable_defined?(ivar)
+
+    `#{path} --version` =~ /gcc-\d.\d \(GCC\) (\d\.\d\.\d)/
+    instance_variable_set(ivar, $1)
+  end
+
   # See these issues for some history:
   # http://github.com/mxcl/homebrew/issues/#issue/13
   # http://github.com/mxcl/homebrew/issues/#issue/41
diff --git a/Library/Homebrew/test/test_compiler_selector.rb b/Library/Homebrew/test/test_compiler_selector.rb
index 17c3b0449..5374a5452 100644
--- a/Library/Homebrew/test/test_compiler_selector.rb
+++ b/Library/Homebrew/test/test_compiler_selector.rb
@@ -22,16 +22,29 @@ class CompilerSelectorTests < Test::Unit::TestCase
     MacOS.stubs(:gcc_build_version).returns(5666)
     MacOS.stubs(:llvm_build_version).returns(2336)
     MacOS.stubs(:clang_build_version).returns(425)
+    # Yes, this is ugly - we only want one GCC version to be available.
+    MacOS.send(:alias_method, :old_non_apple_gcc_version, :non_apple_gcc_version)
+    MacOS.send(:define_method, :non_apple_gcc_version) do |name|
+      if name == 'gcc-4.8'
+        '4.8.1'
+      else
+        nil
+      end
+    end
     @f  = Double.new
     @cc = :clang
   end
 
+  def teardown
+    MacOS.send(:alias_method, :non_apple_gcc_version, :old_non_apple_gcc_version)
+  end
+
   def actual_cc
     CompilerSelector.new(@f).compiler
   end
 
   def test_all_compiler_failures
-    @f << :clang << :llvm << :gcc
+    @f << :clang << :llvm << :gcc << 'gcc-4.8'
     assert_raise(CompilerSelectionError) { actual_cc }
   end
 
@@ -41,7 +54,7 @@ class CompilerSelectorTests < Test::Unit::TestCase
 
   def test_fails_with_clang
     @f << :clang
-    assert_equal :llvm, actual_cc
+    assert_equal :gcc, actual_cc
   end
 
   def test_fails_with_llvm
@@ -54,13 +67,18 @@ class CompilerSelectorTests < Test::Unit::TestCase
     assert_equal :clang, actual_cc
   end
 
+  def test_fails_with_non_apple_gcc
+    @f << "gcc-4.8"
+    assert_equal :clang, actual_cc
+  end
+
   def test_mixed_failures_1
     @f << :clang << :llvm
     assert_equal :gcc, actual_cc
   end
 
   def test_mixed_failures_2
-    @f << :gcc << :clang
+    @f << :gcc << :clang << 'gcc-4.8'
     assert_equal :llvm, actual_cc
   end
 
@@ -69,22 +87,32 @@ class CompilerSelectorTests < Test::Unit::TestCase
     assert_equal :clang, actual_cc
   end
 
+  def test_mixed_failures_4
+    @f << :clang << "gcc-4.8"
+    assert_equal :gcc, actual_cc
+  end
+
   def test_older_clang_precedence
     MacOS.stubs(:clang_build_version).returns(211)
-    @f << :gcc
+    @f << :gcc << 'gcc-4.8'
     assert_equal :llvm, actual_cc
   end
 
+  def test_non_apple_gcc_precedence
+    @f << :clang << :gcc
+    assert_equal 'gcc-4.8', actual_cc
+  end
+
   def test_missing_gcc
     MacOS.stubs(:gcc_build_version).returns(nil)
-    @f << :clang << :llvm
+    @f << :clang << :llvm << 'gcc-4.8'
     assert_raise(CompilerSelectionError) { actual_cc }
   end
 
   def test_missing_llvm_and_gcc
     MacOS.stubs(:gcc_build_version).returns(nil)
     MacOS.stubs(:llvm_build_version).returns(nil)
-    @f << :clang
+    @f << :clang << 'gcc-4.8'
     assert_raise(CompilerSelectionError) { actual_cc }
   end
 end
diff --git a/Library/Homebrew/test/test_fails_with.rb b/Library/Homebrew/test/test_fails_with.rb
index 2b344cc3d..31f318a4c 100644
--- a/Library/Homebrew/test/test_fails_with.rb
+++ b/Library/Homebrew/test/test_fails_with.rb
@@ -3,7 +3,7 @@ require 'test/testball'
 
 class FailsWithTests < Test::Unit::TestCase
   class Double < Compiler
-    attr_accessor :name, :build
+    attr_accessor :name, :build, :version
   end
 
   def assert_fails_with(cc)
@@ -18,10 +18,11 @@ class FailsWithTests < Test::Unit::TestCase
     @f.send(:fails_with, *args, &block)
   end
 
-  def build_cc(sym, build)
+  def build_cc(sym, build, version=nil)
     cc = Double.new
     cc.name = sym
     cc.build = build
+    cc.version = version
     cc
   end
 
@@ -47,6 +48,12 @@ class FailsWithTests < Test::Unit::TestCase
     assert_fails_with cc
   end
 
+  def test_non_apple_gcc_version
+    fails_with(:gcc => '4.8.2')
+    cc = build_cc("gcc-4.8", nil, "4.8.1")
+    assert_fails_with cc
+  end
+
   def test_multiple_failures
     fails_with(:llvm)
     fails_with(:clang)