From 10949ad75deaca284300f4db0f392d5a6dba77e8 Mon Sep 17 00:00:00 2001
From: Jack Nagel <jacknagel@gmail.com>
Date: Thu, 27 Jun 2013 01:18:32 -0500
Subject: [PATCH] Fix some #eql? correctness issues

The implementation of #eql? and #hash should ensure that if a.eql?(b),
then a.hash == b.hash, but #eql? itself should not *depend* on #hash.

For example, given

  class Thingy
    def eql?
      instance_of?(other.class) && hash == other.hash
    end

    def hash
      [name, *tags].hash
    end
  end

if #hash produces a collision for different values of [name, *tags], two
Thingy objects will appear to be eql?, even though this is not the case.
Instead, #eql? should depend on the equality of name and tags directly.
---
 Library/Homebrew/dependency.rb            |  2 +-
 Library/Homebrew/options.rb               |  2 +-
 Library/Homebrew/requirement.rb           |  2 +-
 Library/Homebrew/test/test_requirement.rb | 14 ++++++++++++++
 4 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/Library/Homebrew/dependency.rb b/Library/Homebrew/dependency.rb
index 05318fc9ad..407623810e 100644
--- a/Library/Homebrew/dependency.rb
+++ b/Library/Homebrew/dependency.rb
@@ -21,7 +21,7 @@ class Dependency
   end
 
   def eql?(other)
-    instance_of?(other.class) && hash == other.hash
+    instance_of?(other.class) && name == other.name
   end
 
   def hash
diff --git a/Library/Homebrew/options.rb b/Library/Homebrew/options.rb
index c7d1acca22..b59cd29300 100644
--- a/Library/Homebrew/options.rb
+++ b/Library/Homebrew/options.rb
@@ -20,7 +20,7 @@ class Option
   end
 
   def eql?(other)
-    other.is_a?(self.class) && hash == other.hash
+    instance_of?(other.class) && name == other.name
   end
 
   def hash
diff --git a/Library/Homebrew/requirement.rb b/Library/Homebrew/requirement.rb
index 317675b739..f710fd0215 100644
--- a/Library/Homebrew/requirement.rb
+++ b/Library/Homebrew/requirement.rb
@@ -54,7 +54,7 @@ class Requirement
   end
 
   def eql?(other)
-    instance_of?(other.class) && hash == other.hash
+    instance_of?(other.class) && name == other.name && tags == other.tags
   end
 
   def hash
diff --git a/Library/Homebrew/test/test_requirement.rb b/Library/Homebrew/test/test_requirement.rb
index 042aa922df..a2e50126e1 100644
--- a/Library/Homebrew/test/test_requirement.rb
+++ b/Library/Homebrew/test/test_requirement.rb
@@ -121,4 +121,18 @@ class RequirementTests < Test::Unit::TestCase
       req.to_dependency.modify_build_environment
     end
   end
+
+  def test_eql
+    a, b = Requirement.new, Requirement.new
+    assert a.eql?(b)
+    assert b.eql?(a)
+    assert_equal a.hash, b.hash
+  end
+
+  def test_not_eql
+    a, b = Requirement.new([:optional]), Requirement.new
+    assert_not_equal a.hash, b.hash
+    assert !a.eql?(b)
+    assert !b.eql?(a)
+  end
 end