0001-Fixing-Hash-constructor-to-not-rehash-keys.patch

From a49caebabb688fc83b01a03e3e970a0228de6f8a Mon Sep 17 00:00:00 2001
From: Gavin Stark <[email protected]>
Date: Sun, 13 Jun 2010 00:54:50 -0400
Subject: [PATCH 1/2] Fixing Hash constructor to not rehash keys.

---
 kernel/common/hash.rb |   48 ++++++++++++++++++++++++++++++++++++++----------
 1 files changed, 38 insertions(+), 10 deletions(-)

diff --git a/kernel/common/hash.rb b/kernel/common/hash.rb
index 3ee4100..2108852 100644
--- a/kernel/common/hash.rb
+++ b/kernel/common/hash.rb
@@ -78,10 +78,8 @@ class Hash
   def self.[](*args)
     if args.size == 1
       obj = args.first
-      if obj.kind_of? Hash
-        return new.replace(obj)
-      elsif obj.respond_to? :to_hash
-        return new.replace(Type.coerce_to(obj, Hash, :to_hash))
+      if obj.kind_of?(Hash) || obj.respond_to?(:to_hash)
+        return new.send(:replace_without_key_hashing,obj)
       elsif obj.is_a?(Array) # See redmine # 1385
         h = {}
         args.first.each do |arr|
@@ -190,12 +188,7 @@ class Hash
     end
   end
 
-  def []=(key, value)
-    Ruby.check_frozen
-
-    redistribute @entries if @size > @max_entries
-
-    key_hash = key.hash
+  def __store_with_precomputed_hash__(key, value, key_hash)
     index = key_hash & @mask # key_index key_hash
 
     entry = @entries[index]
@@ -222,6 +215,17 @@ class Hash
 
     value
   end
+  private :__store_with_precomputed_hash__
+
+  def []=(key, value)
+    Ruby.check_frozen
+
+    redistribute @entries if @size > @max_entries
+
+    key_hash = key.hash
+
+    __store_with_precomputed_hash__(key,value,key_hash)
+  end
 
   alias_method :store, :[]=
 
@@ -586,6 +590,30 @@ class Hash
     end
   end
 
+  def replace_without_key_hashing(other)
+    Ruby.check_frozen
+
+    other = Type.coerce_to other, Hash, :to_hash
+    return self if self.equal? other
+
+    setup
+    i = other.to_iter
+    while entry = i.next(entry)
+      __store_with_precomputed_hash__ entry.key, entry.value, entry.key_hash
+    end
+
+    if other.default_proc
+      @default = other.default_proc
+      @default_proc = true
+    else
+      @default = other.default
+      @default_proc = false
+    end
+
+    self
+  end
+  private :replace_without_key_hashing
+
   # packed! [:@capacity, :@mask, :@max_entries, :@size, :@entries]
 
   # Sets the underlying data structures.
-- 
1.7.1

0002-Adding-new-Hash-constructor-specs.patch

From a9f3316af571b45511dfe1e8852ccef2c82f720c Mon Sep 17 00:00:00 2001
From: Gavin Stark <[email protected]>
Date: Sun, 13 Jun 2010 00:55:02 -0400
Subject: [PATCH 2/2] Adding new Hash constructor specs

---
 spec/ruby/core/hash/constructor_spec.rb |   34 +++++++++++++++++++++++++++++++
 1 files changed, 34 insertions(+), 0 deletions(-)

diff --git a/spec/ruby/core/hash/constructor_spec.rb b/spec/ruby/core/hash/constructor_spec.rb
index 644b24a..9c2d727 100644
--- a/spec/ruby/core/hash/constructor_spec.rb
+++ b/spec/ruby/core/hash/constructor_spec.rb
@@ -2,6 +2,40 @@ require File.expand_path('../../../spec_helper', __FILE__)
 require File.expand_path('../fixtures/classes', __FILE__)
 
 describe "Hash.[]" do
+  it "does not call #hash on elements when provided a hash" do
+    x = mock('x')
+    y = mock('y')
+
+    other = {x => 1, y => 2}
+
+    x.should_not_receive(:hash)
+    y.should_not_receive(:hash)
+
+    hash_class[other]
+  end
+
+  it "does not call #hash on elements when provided a non-Hash object responding to to_hash" do
+    x = mock('x')
+    y = mock('y')
+
+    existing_hash = {x => 1, y => 2}
+
+    x.should_not_receive(:hash)
+    y.should_not_receive(:hash)
+
+    class NotAHash
+      def initialize(existing_hash)
+        @existing_hash = existing_hash
+      end
+
+      def to_hash
+        @existing_hash
+      end
+    end
+
+    hash_class[NotAHash.new(existing_hash)]
+  end
+
   it "creates a Hash; values can be provided as the argument list" do
     hash_class[:a, 1, :b, 2].should == new_hash(:a => 1, :b => 2)
     hash_class[].should == new_hash
-- 
1.7.1