Issues to be fixed to release version 3

• Make most of Message functions non-virtual to reduce generated code size #339
• Remove RepeatedField #503
• Remove serde support from rust-protobuf-3 #519
• Dynamic Message #498
• Message field design #520
• Rename carllerche-bytes codegen option name to tokio-bytes #599
• Move protoc-bin-vendored into a separate repository #601
• Codegen option to create module hierarchy #438
• Support Field Presence (proto3) #513
• Change generated code for version 3 release #521
• Carefully work with integer overflow in serialization and deserialization #530
• Use underscore to escape keywords #618

Version 3 alpha versions are published. docs.rs

Open questions:

• Is current proto file placing OK? I. e. all files become first-level modules regardless of input directory structure and package declaration. I. e. foo/bar.proto becomes mod bar
• Do we need to rename .proto member to rust idiomatic names? I. e. do we need to rename enum variant FOO to Foo?
• Should we use raw identifiers for reserved names? Currently proto field type becomes field_type in generated code. Perhaps it should be r#type.
• What about MessageField type? It is convenient, but isn't it too much mental overhead to work with?
• Should we get rid of hack around figuring out how place messages in oneofs? They are boxed when there's a loop, and unboxed otherwise. I'm in favor of unconditionally making them boxed. Maybe later provide codegen option to store then unboxed.
• Is codegen customize callback API convenient?
• Shouldn't we pull JSON/text format parsing and serialization out of protobuf crate? For JSON we would be able to use third-party JSON parser more easily
• should we restrict generated code only to current version of rust-protobuf? Or guarantee forward compatibility with generated code as rust-protobuf v2 did? Not guaranteeing compatibility would make future changes around reflection much easier.