protoc --descriptor_set_out should include FileDescriptorProto.source_code_info like protoc --XXX_out

[timostamm]

What version of protobuf and what language are you using?
Version: 3.12.3
Language: n/a

What operating system (Linux, Windows, ...) and version?
n/a

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

What did you do?
Steps to reproduce the behavior:

1. create comments.proto:

syntax = "proto3";
package testing;
message MessageWithComments {
    // Leading field comment.
    string foo = 1;
}

2. Write a FileDescriptorSet for it:

$ protoc --descriptor_set_out temp comments.proto

3. Text-format it:

protoc < temp --decode=google.protobuf.FileDescriptorSet google/protobuf/descriptor.proto

What did you expect to see

SourceCodeInfo with comments:

file {
  name: "comments.proto"
  package: "testing"
  message_type {
    name: "MessageWithComments"
    field {
      name: "foo"
      number: 1
      label: LABEL_OPTIONAL
      type: TYPE_STRING
      json_name: "foo"
    }
  }
  source_code_info {
    …
    location {
      path: 4
      path: 0
      path: 2
      path: 0
      span: 4
      span: 4
      span: 19
      leading_comments: " Leading field comment.\n"
    }
    …
  }
  syntax: "proto3"
}

What did you see instead?

$ protoc < temp --decode=google.protobuf.FileDescriptorSet google/protobuf/descriptor.proto
file {
  name: "comments.proto"
  package: "testing"
  message_type {
    name: "MessageWithComments"
    field {
      name: "foo"
      number: 1
      label: LABEL_OPTIONAL
      type: TYPE_STRING
      json_name: "foo"
    }
  }
  syntax: "proto3"
}

Anything else we should know about your project / environment

Writing a protoc plugin, wanted to use --descriptor_set_out to generate data for unit tests.

[thomasvl]

Drive by, from protoc --help

  --include_source_info       When using --descriptor_set_out, do not strip
                              SourceCodeInfo from the FileDescriptorProto.
                              This results in vastly larger descriptors that
                              include information about the original
                              location of each decl in the source file as
                              well as surrounding comments.

[timostamm]

Apparently I did not RTFM.

Thank you for the nudge @thomasvl , much appreciated.