[ruby] decode_json unexpected / inconsistent behaviour parsing JSON

[mt-kelvintaywl]

What version of protobuf and what language are you using?
Protobuf version: 3
ruby gem version: 3.12.0.rc.1
Language: Ruby

What operating system (Linux, Windows, ...) and version?
MacOS 10.14.4

What runtime / compiler are you using (e.g., python version or gcc version)
Ruby 2.7

What did you do?

Assuming i have a generated Ruby class from Protobuf, called MyMessage

# raises Google::Protobuf::ParseError (expected)
MyMessage.decode_json("I cannot understand this", ignore_unknown_fields: true)

# returns a MyMessage.new object (expected since number is a valid JSON)
MyMessage.decode_json("1", ignore_unknown_fields: true)

# returns a MyMessage.new object (unexpected? this is a string so I expected it to throw)
MyMessage.decode_json("1 cannot understand this", ignore_unknown_fields: true) 

Would this be a known or expected behaviour? 🙇

[haberman]

The Ruby JSON decoder may not be properly verifying that it is at end-of-file.

There is a major change to the Ruby implementation coming soon. I'll revisit this bug after that is complete, and we can see if the new JSON parser has the same issue.

[mt-kelvintaywl]

HI @haberman thank you for the updates and details :)
Looking forward to the new releases 🙇

would there also be a public roadmap that we can track the progress of this? 🤔

[haberman]

I just tested your examples on #8184 and all of your examples throw errors now. This is expected since parsing a message from JSON requires a top-level object in {}.

Your second example now throws this error: Error occurred during parsing: Error parsing JSON @1:0: Expected: '{'