> If this SourceCodeInfo represents a complete declaration, these are any > comments appearing before and after the declaration which appear to be > attached to the declaration.
https://github.com/protocolbuffers/protobuf/blob/v21.5/src/g...
After re-reading with this caveat in mind -- that comments are only preserved before and after complete declarations -- I realized that it does retain the comments that are expected.
Long story short: the descriptor is bad as an AST if you care about recovering the original source. The descriptor is lossy. I'd recommend using a real AST for use cases that want something non-lossy: https://pkg.go.dev/github.com/jhump/protoreflect/desc/protop...
1: https://github.com/jvolkman/intellij-protobuf-editor/blob/ma... 2: https://github.com/jvolkman/intellij-protobuf-editor/blob/ma...
Comment placement is basically allowed anywhere by protoc, but how to get those comments within a Descriptor object for a proto is not well defined (there are places where you can put comments that are not available within Descriptor). It provides leading/trailing comments, but there are many other cases that are missed today (like comments embedded within a list of items in an array). Maybe this is a mismatch between what protoc allows and what Descriptor presents, but it's definitely annoying.