Remove Fixnum references to support modern Ruby versions

Fixnum type has been deprecated since Ruby 2.4 and removed in Ruby 3.0,
which makes BaseProtocol incompatible with modern Ruby versions.

This change removes the Fixnum reference, as well as a monkey-patch that
introduces Fixnum#ord() to Ruby versions below 1.8.7.

**This change essentially makes it officially required to use Ruby 2.4 or newer.**

Fixes the following test failures:

  1) BaseProtocol Thrift::BaseProtocol should write out the different types (deprecated write_type signature)
     Failure/Error: if field_info.is_a? Fixnum

     NameError:
       uninitialized constant Thrift::BaseProtocol::Fixnum
     # ./lib/thrift/protocol/base_protocol.rb:256:in 'Thrift::BaseProtocol#write_type'
     # ./spec/base_protocol_spec.rb:65:in 'block (3 levels) in <top (required)>'

  2) BaseProtocol Thrift::BaseProtocol should write out the different types
     Failure/Error: if field_info.is_a? Fixnum

     NameError:
       uninitialized constant Thrift::BaseProtocol::Fixnum
     # ./lib/thrift/protocol/base_protocol.rb:256:in 'Thrift::BaseProtocol#write_type'
     # ./spec/base_protocol_spec.rb:90:in 'block (3 levels) in <top (required)>'

  3) BaseProtocol Thrift::BaseProtocol should read the different types (deprecated read_type signature)
     Failure/Error: if field_info.is_a? Fixnum

     NameError:
       uninitialized constant Thrift::BaseProtocol::Fixnum
     # ./lib/thrift/protocol/base_protocol.rb:296:in 'Thrift::BaseProtocol#read_type'
     # ./spec/base_protocol_spec.rb:113:in 'block (3 levels) in <top (required)>'

  4) BaseProtocol Thrift::BaseProtocol should read the different types
     Failure/Error: if field_info.is_a? Fixnum

     NameError:
       uninitialized constant Thrift::BaseProtocol::Fixnum
     # ./lib/thrift/protocol/base_protocol.rb:296:in 'Thrift::BaseProtocol#read_type'
     # ./spec/base_protocol_spec.rb:136:in 'block (3 levels) in <top (required)>'

Author: kpumuk

LANGUAGES.md

@@ -312,7 +312,7 @@ Thrift's core protocol is TBinary, supported by all languages except for JavaScr
 <td align=left><a href="https://github.com/apache/thrift/blob/master/lib/rb/README.md">Ruby</a></td>
 <!-- Since -----------------><td>0.2.0</td>
 <!-- Build Systems ---------><td><img src="/doc/images/cgrn.png" alt="Yes"/></td><td><img src="/doc/images/cred.png" alt=""/></td>
-<!-- Language Levels -------><td>2.3.1p112</td><td>2.5.1p57</td>
+<!-- Language Levels -------><td>2.4.0</td><td>2.5.1p57</td>
 <!-- Field types -----------><td><img src="/doc/images/cred.png" alt=""/></td>
 <!-- Low-Level Transports --><td><img src="/doc/images/cgrn.png" alt="Yes"/></td><td><img src="/doc/images/cred.png" alt=""/></td><td><img src="/doc/images/cgrn.png" alt="Yes"/></td><td><img src="/doc/images/cred.png" alt=""/></td><td><img src="/doc/images/cgrn.png" alt="Yes"/></td><td><img src="/doc/images/cgrn.png" alt="Yes"/></td>
 <!-- Transport Wrappers ----><td><img src="/doc/images/cgrn.png" alt="Yes"/></td><td><img src="/doc/images/cred.png" alt=""/></td><td><img src="/doc/images/cgrn.png" alt="Yes"/></td><td><img src="/doc/images/cred.png" alt=""/></td>

lib/rb/lib/thrift.rb

@@ -23,7 +23,6 @@
 $:.unshift File.dirname(__FILE__)
 
 require 'thrift/bytes'
-require 'thrift/core_ext'
 require 'thrift/exceptions'
 require 'thrift/types'
 require 'thrift/processor'

lib/rb/lib/thrift/core_ext.rb

@@ -251,9 +251,9 @@ def write_field(*args)
     #
     # Returns nothing.
     def write_type(field_info, value)
-      # if field_info is a Fixnum, assume it is a Thrift::Types constant
+      # if field_info is a Integer, assume it is a Thrift::Types constant
       # convert it into a field_info Hash for backwards compatibility
-      if field_info.is_a? Fixnum
+      if field_info.is_a? Integer
         field_info = {:type => field_info}
       end
 
@@ -291,9 +291,9 @@ def write_type(field_info, value)
     #
     # Returns the value read; object type varies based on field_info[:type].
     def read_type(field_info)
-      # if field_info is a Fixnum, assume it is a Thrift::Types constant
+      # if field_info is a Integer, assume it is a Thrift::Types constant
       # convert it into a field_info Hash for backwards compatibility
-      if field_info.is_a? Fixnum
+      if field_info.is_a? Integer
         field_info = {:type => field_info}
       end
 

lib/rb/lib/thrift/core_ext/fixnum.rb

@@ -62,7 +62,7 @@ def read(sz)
       raise NotImplementedError
     end
 
-    # Returns an unsigned byte as a Fixnum in the range (0..255).
+    # Returns an unsigned byte as a Integer in the range (0..255).
     def read_byte
       buf = read_all(1)
       return Bytes.get_string_byte(buf, 0)

lib/rb/lib/thrift/protocol/base_protocol.rb

@@ -227,7 +227,7 @@ def validate_default_arguments(object)
     it "should support optional type-checking in Thrift::Struct.new" do
       Thrift.type_checking = true
       begin
-        expect { SpecNamespace::Hello.new(:greeting => 3) }.to raise_error(Thrift::TypeError, /Expected Types::STRING, received (Integer|Fixnum) for field greeting/)
+        expect { SpecNamespace::Hello.new(:greeting => 3) }.to raise_error(Thrift::TypeError, "Expected Types::STRING, received Integer for field greeting")
       ensure
         Thrift.type_checking = false
       end
@@ -238,7 +238,7 @@ def validate_default_arguments(object)
       Thrift.type_checking = true
       begin
         hello = SpecNamespace::Hello.new
-        expect { hello.greeting = 3 }.to raise_error(Thrift::TypeError, /Expected Types::STRING, received (Integer|Fixnum) for field greeting/)
+        expect { hello.greeting = 3 }.to raise_error(Thrift::TypeError, "Expected Types::STRING, received Integer for field greeting")
       ensure
         Thrift.type_checking = false
       end

lib/rb/lib/thrift/transport/base_transport.rb

@@ -100,9 +100,9 @@
     end
 
     it "should give the Thrift::TypeError a readable message" do
-      msg = /Expected Types::STRING, received (Integer|Fixnum) for field foo/
+      msg = "Expected Types::STRING, received Integer for field foo"
       expect { Thrift.check_type(3, {:type => Thrift::Types::STRING}, :foo) }.to raise_error(Thrift::TypeError, msg)
-      msg = /Expected Types::STRING, received (Integer|Fixnum) for field foo.element/
+      msg = "Expected Types::STRING, received Integer for field foo.element"
       field = {:type => Thrift::Types::LIST, :element => {:type => Thrift::Types::STRING}}
       expect { Thrift.check_type([3], field, :foo) }.to raise_error(Thrift::TypeError, msg)
       msg = "Expected Types::I32, received NilClass for field foo.element.key"

lib/rb/spec/struct_spec.rb

@@ -12,6 +12,8 @@ Gem::Specification.new do |s|
   s.license     = 'Apache-2.0'
   s.extensions  = ['ext/extconf.rb']
 
+  s.required_ruby_version = '>= 2.4.0'
+
   s.rdoc_options  = %w[--line-numbers --inline-source --title Thrift --main README]
 
   s.rubyforge_project = 'thrift'

lib/rb/spec/types_spec.rb

@@ -225,14 +225,14 @@ def test_enum
     ret = @client.testEnum(val)
 
     assert_equal(ret, 6)
-    assert_kind_of(Fixnum, ret)
+    assert_kind_of(Integer, ret)
   end
 
   def test_typedef
     p 'test_typedef'
     #UserId  testTypedef(1: UserId thing),
     assert_equal(@client.testTypedef(309858235082523), 309858235082523)
-    assert_kind_of(Fixnum, @client.testTypedef(309858235082523))
+    assert_kind_of(Integer, @client.testTypedef(309858235082523))
     true
   end