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.

4 files changed, 6 insertions, 7 deletions

diff --git a/guides/source/5_0_release_notes.md b/guides/source/5_0_release_notes.md
index c2d3e0aeff..2583b32925 100644
--- a/guides/source/5_0_release_notes.md
+++ b/guides/source/5_0_release_notes.md
@@ -881,7 +881,7 @@ Please refer to the [Changelog][active-support] for detailed changes.
     ([commit](https://github.com/rails/rails/commit/a5e507fa0b8180c3d97458a9b86c195e9857d8f6))
 
 *   Added `Integer#positive?` and `Integer#negative?` query methods
-    in the vein of `Fixnum#zero?`.
+    in the vein of `Integer#zero?`.
     ([commit](https://github.com/rails/rails/commit/e54277a45da3c86fecdfa930663d7692fd083daa))
 
 *   Added a bang version to `ActiveSupport::OrderedOptions` get methods which will raise
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md
index 5462e6b2b8..a45690c03f 100644
--- a/guides/source/active_support_core_extensions.md
+++ b/guides/source/active_support_core_extensions.md
@@ -252,7 +252,7 @@ Note that `try` will swallow no-method errors, returning nil instead. If you wan
 
 ```ruby
 @number.try(:nest)  # => nil
-@number.try!(:nest) # NoMethodError: undefined method `nest' for 1:Fixnum
+@number.try!(:nest) # NoMethodError: undefined method `nest' for 1:Integer
 ```
 
 NOTE: Defined in `active_support/core_ext/object/try.rb`.
@@ -1742,7 +1742,7 @@ NOTE: Defined in `active_support/core_ext/string/inflections.rb`.
 The method `constantize` resolves the constant reference expression in its receiver:
 
 ```ruby
-"Fixnum".constantize # => Fixnum
+"Integer".constantize # => Integer
 
 module M
   X = 1
@@ -2611,8 +2611,7 @@ To do so, the method loops over the pairs and builds nodes that depend on the _v
 ```ruby
 XML_TYPE_NAMES = {
   "Symbol"     => "symbol",
-  "Fixnum"     => "integer",
-  "Bignum"     => "integer",
+  "Integer"    => "integer",
   "BigDecimal" => "decimal",
   "Float"      => "float",
   "TrueClass"  => "boolean",
diff --git a/guides/source/api_documentation_guidelines.md b/guides/source/api_documentation_guidelines.md
index cd208c2e13..5b34330936 100644
--- a/guides/source/api_documentation_guidelines.md
+++ b/guides/source/api_documentation_guidelines.md
@@ -120,7 +120,7 @@ On the other hand, big chunks of structured documentation may have a separate "E
 The results of expressions follow them and are introduced by "# => ", vertically aligned:
 
 ```ruby
-# For checking if a fixnum is even or odd.
+# For checking if an integer is even or odd.
 #
 #   1.even? # => false
 #   1.odd?  # => true
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 59eddb6302..82080c4def 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -881,7 +881,7 @@ Rails 4.0 no longer supports loading plugins from `vendor/plugins`. You must rep
 
 * Rails 4.0 has removed the identity map from Active Record, due to [some inconsistencies with associations](https://github.com/rails/rails/commit/302c912bf6bcd0fa200d964ec2dc4a44abe328a6). If you have manually enabled it in your application, you will have to remove the following config that has no effect anymore: `config.active_record.identity_map`.
 
-* The `delete` method in collection associations can now receive `Fixnum` or `String` arguments as record ids, besides records, pretty much like the `destroy` method does. Previously it raised `ActiveRecord::AssociationTypeMismatch` for such arguments. From Rails 4.0 on `delete` automatically tries to find the records matching the given ids before deleting them.
+* The `delete` method in collection associations can now receive `Integer` or `String` arguments as record ids, besides records, pretty much like the `destroy` method does. Previously it raised `ActiveRecord::AssociationTypeMismatch` for such arguments. From Rails 4.0 on `delete` automatically tries to find the records matching the given ids before deleting them.
 
 * In Rails 4.0 when a column or a table is renamed the related indexes are also renamed. If you have migrations which rename the indexes, they are no longer needed.