Support for unified Integer class in Ruby 2.4+

Ruby 2.4 unifies Fixnum and Bignum into Integer: https://bugs.ruby-lang.org/issues/12005

* Forward compat with new unified Integer class in Ruby 2.4+.
* Backward compat with separate Fixnum/Bignum in Ruby 2.2 & 2.3.
* Drops needless Fixnum distinction in docs, preferring Integer.

14 files changed, 67 insertions, 65 deletions

diff --git a/activesupport/lib/active_support/core_ext/class/subclasses.rb b/activesupport/lib/active_support/core_ext/class/subclasses.rb
index b0f9a8be34..1d8c33b43e 100644
--- a/activesupport/lib/active_support/core_ext/class/subclasses.rb
+++ b/activesupport/lib/active_support/core_ext/class/subclasses.rb
@@ -26,8 +26,6 @@ class Class
 
   # Returns an array with the direct children of +self+.
   #
-  #   Integer.subclasses # => [Fixnum, Bignum]
-  #
   #   class Foo; end
   #   class Bar < Foo; end
   #   class Baz < Bar; end
diff --git a/activesupport/lib/active_support/core_ext/hash/conversions.rb b/activesupport/lib/active_support/core_ext/hash/conversions.rb
index dd5ebe6d8d..2fc514cfce 100644
--- a/activesupport/lib/active_support/core_ext/hash/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/hash/conversions.rb
@@ -55,8 +55,7 @@ class Hash
   #
   #     XML_TYPE_NAMES = {
   #       "Symbol"     => "symbol",
-  #       "Fixnum"     => "integer",
-  #       "Bignum"     => "integer",
+  #       "Integer"    => "integer",
   #       "BigDecimal" => "decimal",
   #       "Float"      => "float",
   #       "TrueClass"  => "boolean",
diff --git a/activesupport/lib/active_support/core_ext/numeric/conversions.rb b/activesupport/lib/active_support/core_ext/numeric/conversions.rb
index b25925b9d4..6586a351f8 100644
--- a/activesupport/lib/active_support/core_ext/numeric/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/numeric/conversions.rb
@@ -134,6 +134,12 @@ module ActiveSupport::NumericWithFormat
   deprecate to_formatted_s: :to_s
 end
 
-[Fixnum, Bignum, Float, BigDecimal].each do |klass|
-  klass.prepend(ActiveSupport::NumericWithFormat)
+# Ruby 2.4+ unifies Fixnum & Bignum into Integer.
+if Integer == Fixnum
+  Integer.prepend ActiveSupport::NumericWithFormat
+else
+  Fixnum.prepend ActiveSupport::NumericWithFormat
+  Bignum.prepend ActiveSupport::NumericWithFormat
 end
+Float.prepend ActiveSupport::NumericWithFormat
+BigDecimal.prepend ActiveSupport::NumericWithFormat
diff --git a/activesupport/lib/active_support/core_ext/object/duplicable.rb b/activesupport/lib/active_support/core_ext/object/duplicable.rb
index befa5aee21..9bc5ee65ba 100644
--- a/activesupport/lib/active_support/core_ext/object/duplicable.rb
+++ b/activesupport/lib/active_support/core_ext/object/duplicable.rb
@@ -70,7 +70,7 @@ class Numeric
   # Numbers are not duplicable:
   #
   #  3.duplicable? # => false
-  #  3.dup         # => TypeError: can't dup Fixnum
+  #  3.dup         # => TypeError: can't dup Integer
   def duplicable?
     false
   end
diff --git a/activesupport/lib/active_support/core_ext/object/try.rb b/activesupport/lib/active_support/core_ext/object/try.rb
index 8c16d95b62..3b6d9da216 100644
--- a/activesupport/lib/active_support/core_ext/object/try.rb
+++ b/activesupport/lib/active_support/core_ext/object/try.rb
@@ -99,7 +99,7 @@ class Object
   #
   #   "a".try!(:upcase) # => "A"
   #   nil.try!(:upcase) # => nil
-  #   123.try!(:upcase) # => NoMethodError: undefined method `upcase' for 123:Fixnum
+  #   123.try!(:upcase) # => NoMethodError: undefined method `upcase' for 123:Integer
 end
 
 class Delegator
diff --git a/activesupport/lib/active_support/core_ext/string/access.rb b/activesupport/lib/active_support/core_ext/string/access.rb
index ebd0dd3fc7..213a91aa7a 100644
--- a/activesupport/lib/active_support/core_ext/string/access.rb
+++ b/activesupport/lib/active_support/core_ext/string/access.rb
@@ -1,5 +1,5 @@
 class String
-  # If you pass a single Fixnum, returns a substring of one character at that
+  # If you pass a single integer, returns a substring of one character at that
   # position. The first character of the string is at position 0, the next at
   # position 1, and so on. If a range is supplied, a substring containing
   # characters at offsets given by the range is returned. In both cases, if an
diff --git a/activesupport/lib/active_support/xml_mini.rb b/activesupport/lib/active_support/xml_mini.rb
index df7b081993..99fc26549e 100644
--- a/activesupport/lib/active_support/xml_mini.rb
+++ b/activesupport/lib/active_support/xml_mini.rb
@@ -32,20 +32,25 @@ module ActiveSupport
       "binary" => "base64"
     } unless defined?(DEFAULT_ENCODINGS)
 
-    TYPE_NAMES = {
-      "Symbol"     => "symbol",
-      "Fixnum"     => "integer",
-      "Bignum"     => "integer",
-      "BigDecimal" => "decimal",
-      "Float"      => "float",
-      "TrueClass"  => "boolean",
-      "FalseClass" => "boolean",
-      "Date"       => "date",
-      "DateTime"   => "dateTime",
-      "Time"       => "dateTime",
-      "Array"      => "array",
-      "Hash"       => "hash"
-    } unless defined?(TYPE_NAMES)
+    unless defined?(TYPE_NAMES)
+      TYPE_NAMES = {
+        "Symbol"     => "symbol",
+        "Integer"    => "integer",
+        "BigDecimal" => "decimal",
+        "Float"      => "float",
+        "TrueClass"  => "boolean",
+        "FalseClass" => "boolean",
+        "Date"       => "date",
+        "DateTime"   => "dateTime",
+        "Time"       => "dateTime",
+        "Array"      => "array",
+        "Hash"       => "hash"
+      }
+
+      # No need to map these on Ruby 2.4+
+      TYPE_NAMES["Fixnum"] = "integer" unless Fixnum == Integer
+      TYPE_NAMES["Bignum"] = "integer" unless Bignum == Integer
+    end
 
     FORMATTING = {
       "symbol"   => Proc.new { |symbol| symbol.to_s },
diff --git a/activesupport/test/core_ext/array/conversions_test.rb b/activesupport/test/core_ext/array/conversions_test.rb
index 507e13f968..de36e2026d 100644
--- a/activesupport/test/core_ext/array/conversions_test.rb
+++ b/activesupport/test/core_ext/array/conversions_test.rb
@@ -101,10 +101,10 @@ class ToXmlTest < ActiveSupport::TestCase
   end
 
   def test_to_xml_with_non_hash_elements
-    xml = [1, 2, 3].to_xml(skip_instruct: true, indent: 0)
+    xml = %w[1 2 3].to_xml(skip_instruct: true, indent: 0)
 
-    assert_equal '<fixnums type="array"><fixnum', xml.first(29)
-    assert xml.include?(%(<fixnum type="integer">2</fixnum>)), xml
+    assert_equal '<strings type="array"><string', xml.first(29)
+    assert xml.include?(%(<string>2</string>)), xml
   end
 
   def test_to_xml_with_non_hash_different_type_elements
diff --git a/activesupport/test/core_ext/array/grouping_test.rb b/activesupport/test/core_ext/array/grouping_test.rb
index fb7367b0bf..0682241f0b 100644
--- a/activesupport/test/core_ext/array/grouping_test.rb
+++ b/activesupport/test/core_ext/array/grouping_test.rb
@@ -3,11 +3,12 @@ require 'active_support/core_ext/array'
 
 class GroupingTest < ActiveSupport::TestCase
   def setup
-    Fixnum.send :private, :/  # test we avoid Integer#/ (redefined by mathn)
+    # In Ruby < 2.4, test we avoid Integer#/ (redefined by mathn)
+    Fixnum.send :private, :/ unless Fixnum == Integer
   end
 
   def teardown
-    Fixnum.send :public, :/
+    Fixnum.send :public, :/ unless Fixnum == Integer
   end
 
   def test_in_groups_of_with_perfect_fit
diff --git a/activesupport/test/core_ext/duration_test.rb b/activesupport/test/core_ext/duration_test.rb
index ce69364c68..502e2811fa 100644
--- a/activesupport/test/core_ext/duration_test.rb
+++ b/activesupport/test/core_ext/duration_test.rb
@@ -12,7 +12,7 @@ class DurationTest < ActiveSupport::TestCase
     assert d.is_a?(ActiveSupport::Duration)
     assert_kind_of ActiveSupport::Duration, d
     assert_kind_of Numeric, d
-    assert_kind_of Fixnum, d
+    assert_kind_of Integer, d
     assert !d.is_a?(Hash)
 
     k = Class.new
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index be8583e704..f0a4c4dddc 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -36,12 +36,12 @@ class HashExtTest < ActiveSupport::TestCase
   def setup
     @strings = { 'a' => 1, 'b' => 2 }
     @nested_strings = { 'a' => { 'b' => { 'c' => 3 } } }
-    @symbols = { :a  => 1, :b  => 2 }
+    @symbols = { :a => 1, :b => 2 }
     @nested_symbols = { :a => { :b => { :c => 3 } } }
-    @mixed   = { :a  => 1, 'b' => 2 }
-    @nested_mixed   = { 'a' => { :b => { 'c' => 3 } } }
-    @fixnums = {  0  => 1,  1  => 2 }
-    @nested_fixnums = {  0  => { 1  => { 2 => 3} } }
+    @mixed = { :a => 1, 'b' => 2 }
+    @nested_mixed = { 'a' => { :b => { 'c' => 3 } } }
+    @integers = { 0 => 1, 1 => 2 }
+    @nested_integers = { 0 => { 1 => { 2 => 3} } }
     @illegal_symbols = { [] => 3 }
     @nested_illegal_symbols = { [] => { [] => 3} }
     @upcase_strings = { 'A' => 1, 'B' => 2 }
@@ -196,14 +196,14 @@ class HashExtTest < ActiveSupport::TestCase
     assert_equal @nested_illegal_symbols, @nested_illegal_symbols.deep_dup.deep_symbolize_keys!
   end
 
-  def test_symbolize_keys_preserves_fixnum_keys
-    assert_equal @fixnums, @fixnums.symbolize_keys
-    assert_equal @fixnums, @fixnums.dup.symbolize_keys!
+  def test_symbolize_keys_preserves_integer_keys
+    assert_equal @integers, @integers.symbolize_keys
+    assert_equal @integers, @integers.dup.symbolize_keys!
   end
 
-  def test_deep_symbolize_keys_preserves_fixnum_keys
-    assert_equal @nested_fixnums, @nested_fixnums.deep_symbolize_keys
-    assert_equal @nested_fixnums, @nested_fixnums.deep_dup.deep_symbolize_keys!
+  def test_deep_symbolize_keys_preserves_integer_keys
+    assert_equal @nested_integers, @nested_integers.deep_symbolize_keys
+    assert_equal @nested_integers, @nested_integers.deep_dup.deep_symbolize_keys!
   end
 
   def test_stringify_keys
@@ -299,14 +299,14 @@ class HashExtTest < ActiveSupport::TestCase
     assert_raise(NoMethodError) { @nested_illegal_symbols.with_indifferent_access.deep_dup.deep_symbolize_keys! }
   end
 
-  def test_symbolize_keys_preserves_fixnum_keys_for_hash_with_indifferent_access
-    assert_equal @fixnums, @fixnums.with_indifferent_access.symbolize_keys
-    assert_raise(NoMethodError) { @fixnums.with_indifferent_access.dup.symbolize_keys! }
+  def test_symbolize_keys_preserves_integer_keys_for_hash_with_indifferent_access
+    assert_equal @integers, @integers.with_indifferent_access.symbolize_keys
+    assert_raise(NoMethodError) { @integers.with_indifferent_access.dup.symbolize_keys! }
   end
 
-  def test_deep_symbolize_keys_preserves_fixnum_keys_for_hash_with_indifferent_access
-    assert_equal @nested_fixnums, @nested_fixnums.with_indifferent_access.deep_symbolize_keys
-    assert_raise(NoMethodError) { @nested_fixnums.with_indifferent_access.deep_dup.deep_symbolize_keys! }
+  def test_deep_symbolize_keys_preserves_integer_keys_for_hash_with_indifferent_access
+    assert_equal @nested_integers, @nested_integers.with_indifferent_access.deep_symbolize_keys
+    assert_raise(NoMethodError) { @nested_integers.with_indifferent_access.deep_dup.deep_symbolize_keys! }
   end
 
   def test_stringify_keys_for_hash_with_indifferent_access
diff --git a/activesupport/test/core_ext/numeric_ext_test.rb b/activesupport/test/core_ext/numeric_ext_test.rb
index 5654aeb4f8..69c30a8a9e 100644
--- a/activesupport/test/core_ext/numeric_ext_test.rb
+++ b/activesupport/test/core_ext/numeric_ext_test.rb
@@ -387,16 +387,9 @@ class NumericExtFormattingTest < ActiveSupport::TestCase
   end
 
   def test_to_s__injected_on_proper_types
-    assert_equal Fixnum, 1230.class
     assert_equal '1.23 Thousand', 1230.to_s(:human)
-
-    assert_equal Float, Float(1230).class
     assert_equal '1.23 Thousand', Float(1230).to_s(:human)
-
-    assert_equal Bignum, (100**10).class
     assert_equal '100000 Quadrillion', (100**10).to_s(:human)
-
-    assert_equal BigDecimal, BigDecimal("1000010").class
     assert_equal '1 Million', BigDecimal("1000010").to_s(:human)
   end
 
diff --git a/activesupport/test/core_ext/object/deep_dup_test.rb b/activesupport/test/core_ext/object/deep_dup_test.rb
index 791b5e7172..aa839201ea 100644
--- a/activesupport/test/core_ext/object/deep_dup_test.rb
+++ b/activesupport/test/core_ext/object/deep_dup_test.rb
@@ -51,7 +51,7 @@ class DeepDupTest < ActiveSupport::TestCase
   end
 
   def test_deep_dup_with_hash_class_key
-    hash = { Fixnum => 1 }
+    hash = { Integer => 1 }
     dup = hash.deep_dup
     assert_equal 1, dup.keys.length
   end
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index ec56c500d3..d68a77680b 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -345,7 +345,7 @@ class StringInflectionsTest < ActiveSupport::TestCase
 end
 
 class StringAccessTest < ActiveSupport::TestCase
-  test "#at with Fixnum, returns a substring of one character at that position" do
+  test "#at with Integer, returns a substring of one character at that position" do
     assert_equal "h", "hello".at(0)
   end
 
@@ -358,19 +358,19 @@ class StringAccessTest < ActiveSupport::TestCase
     assert_equal nil, "hello".at(/nonexisting/)
   end
 
-  test "#from with positive Fixnum, returns substring from the given position to the end" do
+  test "#from with positive Integer, returns substring from the given position to the end" do
     assert_equal "llo", "hello".from(2)
   end
 
-  test "#from with negative Fixnum, position is counted from the end" do
+  test "#from with negative Integer, position is counted from the end" do
     assert_equal "lo", "hello".from(-2)
   end
 
-  test "#to with positive Fixnum, substring from the beginning to the given position" do
+  test "#to with positive Integer, substring from the beginning to the given position" do
     assert_equal "hel", "hello".to(2)
   end
 
-  test "#to with negative Fixnum, position is counted from the end" do
+  test "#to with negative Integer, position is counted from the end" do
     assert_equal "hell", "hello".to(-2)
   end
 
@@ -384,14 +384,14 @@ class StringAccessTest < ActiveSupport::TestCase
     assert_equal 'x', 'x'.first
   end
 
-  test "#first with Fixnum, returns a substring from the beginning to position" do
+  test "#first with Integer, returns a substring from the beginning to position" do
     assert_equal "he", "hello".first(2)
     assert_equal "", "hello".first(0)
     assert_equal "hello", "hello".first(10)
     assert_equal 'x', 'x'.first(4)
   end
 
-  test "#first with Fixnum >= string length still returns a new string" do
+  test "#first with Integer >= string length still returns a new string" do
     string = "hello"
     different_string = string.first(5)
     assert_not_same different_string, string
@@ -402,14 +402,14 @@ class StringAccessTest < ActiveSupport::TestCase
     assert_equal 'x', 'x'.last
   end
 
-  test "#last with Fixnum, returns a substring from the end to position" do
+  test "#last with Integer, returns a substring from the end to position" do
     assert_equal "llo", "hello".last(3)
     assert_equal "hello", "hello".last(10)
     assert_equal "", "hello".last(0)
     assert_equal 'x', 'x'.last(4)
   end
 
-  test "#last with Fixnum >= string length still returns a new string" do
+  test "#last with Integer >= string length still returns a new string" do
     string = "hello"
     different_string = string.last(5)
     assert_not_same different_string, string
@@ -682,7 +682,7 @@ class OutputSafetyTest < ActiveSupport::TestCase
     assert_equal @string, @string.html_safe
   end
 
-  test "A fixnum is safe by default" do
+  test "An integer is safe by default" do
     assert 5.html_safe?
   end
 
@@ -813,7 +813,7 @@ class OutputSafetyTest < ActiveSupport::TestCase
     assert_equal ["<p>", "<b>", "<h1>"], @other_string
   end
 
-  test "Concatting a fixnum to safe always yields safe" do
+  test "Concatting an integer to safe always yields safe" do
     string = @string.html_safe
     string = string.concat(13)
     assert_equal "hello".concat(13), string