From 9bac107b31f05cca65d8aab23be05e1b867bd289 Mon Sep 17 00:00:00 2001
From: Misty De Meo <mistydemeo@github.com>
Date: Thu, 3 Nov 2016 16:28:16 -0700
Subject: [PATCH 1/9] Add Version::NULL singleton

---
 Library/Homebrew/test/test_versions.rb | 23 ++++++++++++++++
 Library/Homebrew/version.rb            |  6 ++++
 Library/Homebrew/version/null.rb       | 38 ++++++++++++++++++++++++++
 3 files changed, 67 insertions(+)
 create mode 100644 Library/Homebrew/version/null.rb

diff --git a/Library/Homebrew/test/test_versions.rb b/Library/Homebrew/test/test_versions.rb
index 21bf324a38..6f85fe7a06 100644
--- a/Library/Homebrew/test/test_versions.rb
+++ b/Library/Homebrew/test/test_versions.rb
@@ -30,6 +30,29 @@ class VersionTokenTests < Homebrew::TestCase
   end
 end
 
+class NullVersionTests < Homebrew::TestCase
+  def test_null_version_is_always_smaller
+    assert_operator Version::NULL, :<, version("1")
+  end
+
+  def test_null_version_is_never_greater
+    refute_operator Version::NULL, :>, version("0")
+  end
+
+  def test_null_version_is_not_equal_to_itself
+    refute_eql Version::NULL, Version::NULL
+  end
+
+  def test_null_version_creates_an_empty_string
+    assert_eql "", Version::NULL.to_s
+  end
+
+  def test_null_version_produces_nan_as_a_float
+    # Float::NAN is not equal to itself so compare object IDs
+    assert_eql Float::NAN.object_id, Version::NULL.to_f.object_id
+  end
+end
+
 class VersionNullTokenTests < Homebrew::TestCase
   def test_inspect
     assert_equal "#<Version::NullToken>", Version::NullToken.new.inspect
diff --git a/Library/Homebrew/version.rb b/Library/Homebrew/version.rb
index 60a8336095..433964dc70 100644
--- a/Library/Homebrew/version.rb
+++ b/Library/Homebrew/version.rb
@@ -1,3 +1,5 @@
+require "version/null"
+
 class Version
   include Comparable
 
@@ -206,6 +208,10 @@ class Version
     false
   end
 
+  def null?
+    false
+  end
+
   def <=>(other)
     return unless other.is_a?(Version)
     return 0 if version == other.version
diff --git a/Library/Homebrew/version/null.rb b/Library/Homebrew/version/null.rb
new file mode 100644
index 0000000000..77106bcce2
--- /dev/null
+++ b/Library/Homebrew/version/null.rb
@@ -0,0 +1,38 @@
+class Version
+  NULL = Class.new do
+    include Comparable
+
+    def <=>(_other)
+      -1
+    end
+
+    def eql?(_other)
+      # Makes sure that the same instance of Version::NULL
+      # will never equal itself; normally Comparable#==
+      # will return true for this regardless of the return
+      # value of #<=>
+      false
+    end
+
+    def detected_from_url?
+      false
+    end
+
+    def head?
+      false
+    end
+
+    def null?
+      true
+    end
+
+    def to_f
+      Float::NAN
+    end
+
+    def to_s
+      ""
+    end
+    alias_method :to_str, :to_s
+  end.new
+end

From fbcf500a48bd8a6be2f009c35be5ae971e841b87 Mon Sep 17 00:00:00 2001
From: Misty De Meo <mistydemeo@github.com>
Date: Thu, 3 Nov 2016 16:36:20 -0700
Subject: [PATCH 2/9] Version.parse: return Version::NULL for unparseable
 strings

---
 Library/Homebrew/test/testing_env.rb | 2 +-
 Library/Homebrew/version.rb          | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Library/Homebrew/test/testing_env.rb b/Library/Homebrew/test/testing_env.rb
index 5f98ace15d..4f2619464b 100644
--- a/Library/Homebrew/test/testing_env.rb
+++ b/Library/Homebrew/test/testing_env.rb
@@ -36,7 +36,7 @@ module Homebrew
     end
 
     def assert_version_nil(url)
-      assert_nil Version.parse(url)
+      assert Version.parse(url).null?
     end
   end
 
diff --git a/Library/Homebrew/version.rb b/Library/Homebrew/version.rb
index 433964dc70..57a9c11a50 100644
--- a/Library/Homebrew/version.rb
+++ b/Library/Homebrew/version.rb
@@ -287,7 +287,7 @@ class Version
 
   def self.parse(spec)
     version = _parse(spec)
-    new(version) unless version.nil?
+    version.nil? ? NULL : new(version)
   end
 
   def self._parse(spec)

From b6acb9cb47817631a69fba31a4cab2cae30da01b Mon Sep 17 00:00:00 2001
From: Misty De Meo <mistydemeo@github.com>
Date: Thu, 3 Nov 2016 16:43:31 -0700
Subject: [PATCH 3/9] Version: allow comparing against nil

---
 Library/Homebrew/test/test_versions.rb | 4 ++++
 Library/Homebrew/version.rb            | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/Library/Homebrew/test/test_versions.rb b/Library/Homebrew/test/test_versions.rb
index 6f85fe7a06..3e1c97b03a 100644
--- a/Library/Homebrew/test/test_versions.rb
+++ b/Library/Homebrew/test/test_versions.rb
@@ -145,6 +145,10 @@ class VersionComparisonTests < Homebrew::TestCase
     assert_operator version("2-p194"), :<, version("2.1-p195")
   end
 
+  def test_comparing_against_nil
+    assert_operator version("2.1.0-p194"), :>, nil
+  end
+
   def test_comparison_returns_nil_for_non_version
     v = version("1.0")
     assert_nil v <=> Object.new
diff --git a/Library/Homebrew/version.rb b/Library/Homebrew/version.rb
index 57a9c11a50..56ffc9a642 100644
--- a/Library/Homebrew/version.rb
+++ b/Library/Homebrew/version.rb
@@ -213,6 +213,8 @@ class Version
   end
 
   def <=>(other)
+    return 1 if other.nil?
+
     return unless other.is_a?(Version)
     return 0 if version == other.version
     return 1 if head? && !other.head?

From 16529a4de5c24f62574ba0b7dbc033f5323e7afb Mon Sep 17 00:00:00 2001
From: Misty De Meo <mistydemeo@github.com>
Date: Thu, 3 Nov 2016 16:47:18 -0700
Subject: [PATCH 4/9] Version: allow coercing non-versions in comparisons

These are needed due to the raw string and fixnum comparisons which
exist for legacy reasons, for instance compiler version and build
comparisons.
---
 Library/Homebrew/test/test_versions.rb | 5 +++++
 Library/Homebrew/version.rb            | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/Library/Homebrew/test/test_versions.rb b/Library/Homebrew/test/test_versions.rb
index 3e1c97b03a..a6e922178f 100644
--- a/Library/Homebrew/test/test_versions.rb
+++ b/Library/Homebrew/test/test_versions.rb
@@ -149,6 +149,11 @@ class VersionComparisonTests < Homebrew::TestCase
     assert_operator version("2.1.0-p194"), :>, nil
   end
 
+  def test_comparing_against_strings
+    assert_operator version("2.1.0-p194"), :==, "2.1.0-p194"
+    assert_operator version("1"), :==, 1
+  end
+
   def test_comparison_returns_nil_for_non_version
     v = version("1.0")
     assert_nil v <=> Object.new
diff --git a/Library/Homebrew/version.rb b/Library/Homebrew/version.rb
index 56ffc9a642..f5fdb09669 100644
--- a/Library/Homebrew/version.rb
+++ b/Library/Homebrew/version.rb
@@ -213,6 +213,11 @@ class Version
   end
 
   def <=>(other)
+    # Needed to retain API compatibility with older string comparisons
+    # for compiler versions, etc.
+    other = Version.new(other) if other.is_a? String
+    # Used by the *_build_version comparisons, which formerly returned Fixnum
+    other = Version.new(other.to_s) if other.is_a? Integer
     return 1 if other.nil?
 
     return unless other.is_a?(Version)

From 20bbeb5e9c4cdd5fb5b7cc92b46325d86b543cf8 Mon Sep 17 00:00:00 2001
From: Misty De Meo <mistydemeo@github.com>
Date: Thu, 3 Nov 2016 16:48:51 -0700
Subject: [PATCH 5/9] Return compiler versions and builds as Versions

---
 Library/Homebrew/compilers.rb         | 11 +++++++++--
 Library/Homebrew/development_tools.rb | 22 +++++++++++++++++-----
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/Library/Homebrew/compilers.rb b/Library/Homebrew/compilers.rb
index 7503f1d77e..b6c87aeca8 100644
--- a/Library/Homebrew/compilers.rb
+++ b/Library/Homebrew/compilers.rb
@@ -14,7 +14,14 @@ end
 
 class CompilerFailure
   attr_reader :name
-  attr_rw :version
+
+  def version(val = nil)
+    if val
+      @version = Version.parse(val.to_s)
+    else
+      @version
+    end
+  end
 
   # Allows Apple compiler `fails_with` statements to keep using `build`
   # even though `build` and `version` are the same internally
@@ -45,7 +52,7 @@ class CompilerFailure
 
   def initialize(name, version, &block)
     @name = name
-    @version = version
+    @version = Version.parse(version.to_s)
     instance_eval(&block) if block_given?
   end
 
diff --git a/Library/Homebrew/development_tools.rb b/Library/Homebrew/development_tools.rb
index 3e1f16d2ab..febe04b216 100644
--- a/Library/Homebrew/development_tools.rb
+++ b/Library/Homebrew/development_tools.rb
@@ -44,7 +44,9 @@ class DevelopmentTools
     def gcc_40_build_version
       @gcc_40_build_version ||=
         if (path = locate("gcc-4.0"))
-          `#{path} --version 2>/dev/null`[/build (\d{4,})/, 1].to_i
+          Version.new `#{path} --version 2>/dev/null`[/build (\d{4,})/, 1].to_i
+        else
+          Version::NULL
         end
     end
     alias gcc_4_0_build_version gcc_40_build_version
@@ -54,7 +56,9 @@ class DevelopmentTools
         begin
           gcc = locate("gcc-4.2") || HOMEBREW_PREFIX.join("opt/apple-gcc42/bin/gcc-4.2")
           if gcc.exist? && !gcc.realpath.basename.to_s.start_with?("llvm")
-            `#{gcc} --version 2>/dev/null`[/build (\d{4,})/, 1].to_i
+            Version.new `#{gcc} --version 2>/dev/null`[/build (\d{4,})/, 1]
+          else
+            Version::NULL
           end
         end
     end
@@ -63,14 +67,18 @@ class DevelopmentTools
     def clang_version
       @clang_version ||=
         if (path = locate("clang"))
-          `#{path} --version`[/(?:clang|LLVM) version (\d\.\d)/, 1]
+          Version.new `#{path} --version`[/(?:clang|LLVM) version (\d\.\d)/, 1]
+        else
+          Version::NULL
         end
     end
 
     def clang_build_version
       @clang_build_version ||=
         if (path = locate("clang"))
-          `#{path} --version`[/clang-(\d{2,})/, 1].to_i
+          Version.new `#{path} --version`[/clang-(\d{2,})/, 1]
+        else
+          Version::NULL
         end
     end
 
@@ -78,7 +86,11 @@ class DevelopmentTools
       (@non_apple_gcc_version ||= {}).fetch(cc) do
         path = HOMEBREW_PREFIX.join("opt", "gcc", "bin", cc)
         path = locate(cc) unless path.exist?
-        version = `#{path} --version`[/gcc(?:-\d(?:\.\d)? \(.+\))? (\d\.\d\.\d)/, 1] if path
+        version = if path
+          Version.new(`#{path} --version`[/gcc(?:-\d(?:\.\d)? \(.+\))? (\d\.\d\.\d)/, 1])
+        else
+          Version::NULL
+        end
         @non_apple_gcc_version[cc] = version
       end
     end

From d32a1c4c7da96d5cbf12197be1707364d081fa88 Mon Sep 17 00:00:00 2001
From: Misty De Meo <mistydemeo@github.com>
Date: Thu, 3 Nov 2016 16:54:20 -0700
Subject: [PATCH 6/9] Version: add #to_f

This is used by things which used to compare against raw strings,
for example Xcode.uncached_version
---
 Library/Homebrew/version.rb | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Library/Homebrew/version.rb b/Library/Homebrew/version.rb
index f5fdb09669..0f3cbb7737 100644
--- a/Library/Homebrew/version.rb
+++ b/Library/Homebrew/version.rb
@@ -260,6 +260,10 @@ class Version
     version.hash
   end
 
+  def to_f
+    version.to_f
+  end
+
   def to_s
     version.dup
   end

From 4e3d23ad14b29832f14784939acc5afe2f1b28f8 Mon Sep 17 00:00:00 2001
From: Misty De Meo <mistydemeo@github.com>
Date: Thu, 3 Nov 2016 16:52:40 -0700
Subject: [PATCH 7/9] Resource: set version to nil if version is null

Is this the right fix? This fixes version cascading from the parent.
---
 Library/Homebrew/resource.rb | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Library/Homebrew/resource.rb b/Library/Homebrew/resource.rb
index fe18f14ddc..c0e9dbadae 100644
--- a/Library/Homebrew/resource.rb
+++ b/Library/Homebrew/resource.rb
@@ -145,7 +145,10 @@ class Resource
   end
 
   def version(val = nil)
-    @version ||= detect_version(val)
+    @version ||= begin
+      version = detect_version(val)
+      version.null? ? nil : version
+    end
   end
 
   def mirror(val)
@@ -155,7 +158,7 @@ class Resource
   private
 
   def detect_version(val)
-    return if val.nil? && url.nil?
+    return Version::NULL if val.nil? && url.nil?
 
     case val
     when nil     then Version.detect(url, specs)

From d8c19fd7d5f658f17f63f1136de6f80a46be0d76 Mon Sep 17 00:00:00 2001
From: Misty De Meo <mistydemeo@github.com>
Date: Thu, 3 Nov 2016 16:52:58 -0700
Subject: [PATCH 8/9] SystemConfig: fix version reporting

---
 Library/Homebrew/system_config.rb | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Library/Homebrew/system_config.rb b/Library/Homebrew/system_config.rb
index 555493c0dd..9c7a8d1b01 100644
--- a/Library/Homebrew/system_config.rb
+++ b/Library/Homebrew/system_config.rb
@@ -143,9 +143,9 @@ class SystemConfig
       f.puts "HOMEBREW_BOTTLE_DOMAIN: #{BottleSpecification::DEFAULT_DOMAIN}"
       f.puts hardware if hardware
       f.puts "Homebrew Ruby: #{describe_homebrew_ruby}"
-      f.puts "GCC-4.0: build #{gcc_40}" if gcc_40
-      f.puts "GCC-4.2: build #{gcc_42}" if gcc_42
-      f.puts "Clang: #{clang ? "#{clang} build #{clang_build}" : "N/A"}"
+      f.puts "GCC-4.0: build #{gcc_40}" unless gcc_40.null?
+      f.puts "GCC-4.2: build #{gcc_42}" unless gcc_42.null?
+      f.puts "Clang: #{clang.null? ? "N/A" : "#{clang} build #{clang_build}"}"
       f.puts "Git: #{describe_git}"
       f.puts "Perl: #{describe_perl}"
       f.puts "Python: #{describe_python}"

From c7be025229dbbe86d85982a135c75b04c9ba00f2 Mon Sep 17 00:00:00 2001
From: Misty De Meo <mistydemeo@github.com>
Date: Tue, 8 Nov 2016 13:25:44 -0800
Subject: [PATCH 9/9] CompilerSelector: fix null check, tests

---
 Library/Homebrew/compilers.rb                   |  4 ++--
 Library/Homebrew/test/test_compiler_selector.rb | 16 +++++++++-------
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/Library/Homebrew/compilers.rb b/Library/Homebrew/compilers.rb
index b6c87aeca8..cf614644c0 100644
--- a/Library/Homebrew/compilers.rb
+++ b/Library/Homebrew/compilers.rb
@@ -122,13 +122,13 @@ class CompilerSelector
         GNU_GCC_VERSIONS.reverse_each do |v|
           name = "gcc-#{v}"
           version = compiler_version(name)
-          yield Compiler.new(name, version) if version
+          yield Compiler.new(name, version) unless version.null?
         end
       when :llvm
         # no-op. DSL supported, compiler is not.
       else
         version = compiler_version(compiler)
-        yield Compiler.new(compiler, version) if version
+        yield Compiler.new(compiler, version) unless version.null?
       end
     end
   end
diff --git a/Library/Homebrew/test/test_compiler_selector.rb b/Library/Homebrew/test/test_compiler_selector.rb
index 0363cacd29..b1591bdbec 100644
--- a/Library/Homebrew/test/test_compiler_selector.rb
+++ b/Library/Homebrew/test/test_compiler_selector.rb
@@ -15,15 +15,17 @@ class CompilerSelectorTests < Homebrew::TestCase
       :clang_build_version
 
     def initialize
-      @gcc_4_0_build_version = nil
-      @gcc_build_version = 5666
-      @clang_build_version = 425
+      @gcc_4_0_build_version = Version::NULL
+      @gcc_build_version = Version.create("5666")
+      @llvm_build_version = Version::NULL
+      @clang_build_version = Version.create("425")
     end
 
     def non_apple_gcc_version(name)
       case name
-      when "gcc-4.8" then "4.8.1"
-      when "gcc-4.7" then "4.7.1"
+      when "gcc-4.8" then Version.create("4.8.1")
+      when "gcc-4.7" then Version.create("4.7.1")
+      else Version::NULL
       end
     end
   end
@@ -101,13 +103,13 @@ class CompilerSelectorTests < Homebrew::TestCase
   end
 
   def test_missing_gcc
-    @versions.gcc_build_version = nil
+    @versions.gcc_build_version = Version::NULL
     @f << :clang << :llvm << { gcc: "4.8" } << { gcc: "4.7" }
     assert_raises(CompilerSelectionError) { actual_cc }
   end
 
   def test_missing_llvm_and_gcc
-    @versions.gcc_build_version = nil
+    @versions.gcc_build_version = Version::NULL
     @f << :clang << { gcc: "4.8" } << { gcc: "4.7" }
     assert_raises(CompilerSelectionError) { actual_cc }
   end