prost_build::compile_protos could return information on the generated files

[Moxinilian]

Hello.
I am writing a wrapper library for a networking protocol that uses protobuf.
Among the wrapping I do, I want to make the interface backend-agnostic, and add IDs automatically attributed to all message types.
However, I find the task unnecessary difficult: adding the automated IDs requires me to parse prost_build's output, and juggle with modules.

The task would be much easier if prost_build::compile_protos returned information on what it built, most notably the message's names, as with that it is easy to generate code that will implement a custom trait on those structs.

[danburkert]

protoc has a concept of plugins which can be used for inserting snippets into the generated code. See https://developers.google.com/protocol-buffers/docs/reference/other for more info. prost doesn't have support for that type of plugin at this point. For protobuf services there is the ServiceGenerator API, though.

That being said, I think a better solution to this is not to add hooks deep into prost code generation, but instead see if you could solve it by creating your own custom derive implementation and annotating the prost generated messages with a derive annotation via type_attribute. This has the considerable upside that you can annotate any struct, not just prost-generated types.