docs reference nonexistent flag

[kevinburke1]

This page: https://developers.google.com/protocol-buffers/docs/reference/go-generated

makes several references to a "go_opt" flag, which as far as I can tell, does not exist with the latest installed protoc version.

[neild]

You most likely have an older version of protoc installed. The most recent version is v3.17.2. You can check the version you are using with protoc --version.

[kevinburke1]

I just updated to 3.17.2 and here's what I get:

$ protoc --version
libprotoc 3.17.2
$ protoc -I. --go_opt=Mgoogle/protobuf/field_mask.proto=github.com/google/go-genproto/protobuf/field_mask,plugins=grpc:./ ./google_libphonenumber/resources/*.proto
Unknown flag: --go_opt

[kevinburke1]

Ah, okay, I can get a different error message if I also specify the "--go_out" flag. I guess that's pretty confusing behavior.

Now I need to figure out how to get the import path to work, I'm trying the "M" flag from the docs and it's not working.

[neild]

Ah, looks like protoc only kind of has a --foo_opt flag if you also specify --foo_out. Yep, that's super confusing.

You shouldn't need to specify a M flag for field_mask.proto. It looks like libphonenumber doesn't have go_package options in its .proto files, however, so you'll need something like:

--go_opt=Mgoogle_libphonenumber/resources/phonenumber.proto=<import path here>
--go_opt=Mgoogle_libphonenumber/resources/phonemetadata.proto=<import path here>
--go_opt=plugins=grpc # Although I strongly recommend using the latest go-grpc plugin and --go-grpc_out=... instead.
--go_out=<output here>

[kevinburke1]

Thanks for the help - I ended up getting it sorted out here, ttacon/libphonenumber#107

[LordMoMA]

Sorry, may I know why you fix "Unknown flag: --go_opt"? I tried almost every method available but in vain.