Compiling a proto that uses a vendored descriptor.proto

I am considering writing a protoc-gen plugin using wire for handling CodeGeneratorRequest. However, I'm having trouble getting the proto to compile due to interactions with handling of built-in types.

The protos I am trying to compile are the same as in the protobuf.dart project.

https://github.com/google/protobuf.dart/tree/master/protoc_plugin/protos

The compiler complains that google/protobuf/descriptor.proto isn't imported even though these are defined in the vendored descriptor.proto.

> descriptor.proto needs to import google/protobuf/descriptor.proto
    for field file (/Users/anuraag/git/connect-kotlin/protoc-gen-connect-kotlin/src/main/proto/descriptor.proto:58:3)
    in message google.protobuf.FileDescriptorSet (/Users/anuraag/git/connect-kotlin/protoc-gen-connect-kotlin/src/main/proto/descriptor.proto:57:1)
  descriptor.proto needs to import google/protobuf/descriptor.proto
    for field message_type (/Users/anuraag/git/connect-kotlin/protoc-gen-connect-kotlin/src/main/proto/descriptor.proto:75:3)
    in message google.protobuf.FileDescriptorProto (/Users/anuraag/git/connect-kotlin/protoc-gen-connect-kotlin/src/main/proto/descriptor.proto:62:1)
  plugin.proto needs to import google/protobuf/descriptor.proto
    for field proto_file (/Users/anuraag/git/connect-kotlin/protoc-gen-connect-kotlin/src/main/proto/plugin.proto:91:3)
    in message google.protobuf.compiler.CodeGeneratorRequest (/Users/anuraag/git/connect-kotlin/protoc-gen-connect-kotlin/src/main/proto/plugin.proto:68:1)
  plugin.proto needs to import google/protobuf/descriptor.proto
    for field generated_code_info (/Users/anuraag/git/connect-kotlin/protoc-gen-connect-kotlin/src/main/proto/plugin.proto:180:5)
    in message google.protobuf.compiler.CodeGeneratorResponse.File (/Users/anuraag/git/connect-kotlin/protoc-gen-connect-kotlin/src/main/proto/plugin.proto:121:3)
    in message google.protobuf.compiler.CodeGeneratorResponse (/Users/anuraag/git/connect-kotlin/protoc-gen-connect-kotlin/src/main/proto/plugin.proto:99:1)

If I remove descriptor.proto and change the import from vendored to standard google/protobuf/descriptor.proto, it succeeds and generates a file referencing descriptor.proto

package com.google.protobuf.compiler

import com.google.protobuf.FileDescriptorProto
import com.squareup.wire.FieldEncoding
import com.squareup.wire.Message
import com.squareup.wire.ProtoAdapter

But FileDescriptorProto doesn't exist, and I couldn't generate it because of the above error. I looked through wire-runtime and wire-schema and couldn't find the class published officially.

I can workaround by changing the package of the protos, but protoc can compile these files. I'm wondering if there is a metric that wire compiler is supposed to be able to compile any file that protoc can.

I'm wondering if either, the descriptor built-in-types are being eagerly used even when not relevant in this case? Or should the wire versions of these protos be published in an artifact?

Reproduce the failure with the vendored descriptor.proto and plugin.proto files described in the issue, then inspect wire-schema and wire-runtime for how built-in descriptor types are resolved or published. Done would require a documented resolution for compiling these protos, including whether Wire supports the protoc behavior or provides the missing generated types.