commit 34908e28983f1db5572e1fdf7c5a89a8b06c5f9a
author Iori IKEDA <8983747+NotFounds@users.noreply.github.com> Thu Dec 14 08:02:45 2023 -0800
committer Copybara-Service <copybara-worker@google.com> Thu Dec 14 08:06:37 2023 -0800
tree 36a866f426ac0dff7d420855dd761b2b0fca6edd
parent 2d7376ea378b14548b1d417df285a0a5c84957ba

Fix TypeError when passing an instance of a subclass of String to a string field (#13818)

## Issue
When an object that is an instance of a string-derived class is passed to a string field in a protobuf message in Ruby, it results in a `Google::Protobuf::TypeError`.

### Steps to reproduce
```rb
~/src/github.com/protocolbuffers/protobuf/ruby/tests ❯❯❯ irb -I .
irb(main):001:0> require 'basic_test_pb'
=> true
irb(main):002:0> myString = Class.new(String)
=> #<Class:0x00000001531540d8>
irb(main):003:0> str = myString.new("foo")
=> "foo"
irb(main):004:0> BasicTest::TestMessage.new(optional_string: "foo")
=> <BasicTest::TestMessage: optional_string: "foo", repeated_int32: [], repeated_int64: [], repeated_uint32: [], repeated_uint64: [], repeated_bool: [], repeated_float: [], repeated_double: [], repeated_string: [], repeated_bytes: [], repeated_msg: [], repeated_enum: []>
irb(main):005:0> BasicTest::TestMessage.new(optional_string: str)
(irb):5:in `initialize': Invalid argument for string field 'optional_string' (given #<Class:0x00000001531540d8>). (Google::Protobuf::TypeError)
irb(main):006:0>
```

## Fix
The issue appears to be caused by the field checking mechanism not properly handling instances of classes that inherit from basic types like String. My proposed solution is to improve the type checking for string fields to consider not just String instances but also instances of subclasses of String.

## Impact
The changes will allow instances of classes derived from String to be passed to string fields without any error.
This is a backwards-compatible change and will not affect the existing behaviour with standard String instances.

Closes #13818

COPYBARA_INTEGRATE_REVIEW=https://github.com/protocolbuffers/protobuf/pull/13818 from NotFounds:support-string-subclass-for-ruby 2d2796c4f96d5a182a269b54e893f436f2211ea2
PiperOrigin-RevId: 590941235