Grpc-gateway: Migrate away from using the protoc-gen-go/generator package

[johanbrandhorst]

This is internal and will be deprecated in a future release of golang/protobuf

[nashikb]

Yes please.

[Greg0x01]

Hi @johanbrandhorst ,
after getting warning WARNING: Package "github.com/golang/protobuf/protoc-gen-go/generator" is deprecated. I've found this issue and tested lastest master version and get same warning. I've found other places where deprecated package is still imported:

egrep -iR 'github.com/golang/protobuf/protoc-gen-go/generator' .

./protoc-gen-grpc-gateway/internal/gengateway/template.go:      generator2 "github.com/golang/protobuf/protoc-gen-go/generator"
./protoc-gen-grpc-gateway/descriptor/types.go:  gogen "github.com/golang/protobuf/protoc-gen-go/generator"
./examples/internal/server/fieldmask_helper.go: "github.com/golang/protobuf/protoc-gen-go/generator"

Should these places migrate away from package github.com/golang/protobuf/protoc-gen-go/generator too?

I'm concerned with case of a future release of golang/protobuf that will delete it and break go build process.

[johanbrandhorst]

This is indeed not resolved yet. We'd be happy to accept contributions to remove these dependencies.

[johanbrandhorst]

The case of migrating from github.com/golang/protobuf/protoc-gen-go/generator is going to be more complicated, but also something we want to do long term.

[achew22]

Since we have a partial implementation, could we move it into our internal/generator package and then change the imports?

[johanbrandhorst]

Sounds good :+1:. We should be able to copy parts of the dependency as long as we include the LICENSE I believe?

[achew22]

Step one is always collect data:

$ ag github.com/golang/protobuf/protoc-gen-go/generator
protoc-gen-grpc-gateway/internal/gengateway/template.go
11:     generator2 "github.com/golang/protobuf/protoc-gen-go/generator"

protoc-gen-grpc-gateway/descriptor/types.go
8:      gogen "github.com/golang/protobuf/protoc-gen-go/generator"

examples/internal/server/fieldmask_helper.go
8:      "github.com/golang/protobuf/protoc-gen-go/generator"

Let's see what the usage looks like.

$ ag generator2 protoc-gen-grpc-gateway/internal/gengateway/template.go
11:     generator2 "github.com/golang/protobuf/protoc-gen-go/generator"
41:             return generator2.CamelCase(b.Body.FieldPath.String()), nil
125:            return generator2.CamelCase(fieldMaskField.GetName())
159:            msgName := generator2.CamelCase(*msg.Name)
164:            svcName := generator2.CamelCase(*svc.Name)
168:                    methName := generator2.CamelCase(*meth.Name)

$ ag gogen protoc-gen-grpc-gateway/descriptor/types.go
8:      gogen "github.com/golang/protobuf/protoc-gen-go/generator"
319:                    oneOfName := gogen.CamelCase(msg.GetOneofDecl()[*index].GetName())
355:    return gogen.CamelCase(c.Name)
361:            return fmt.Sprintf("Get%s()", gogen.CamelCase(c.Name))
363:    return gogen.CamelCase(c.Name)

$ ag generator examples/internal/server/fieldmask_helper.go
8:      "github.com/golang/protobuf/protoc-gen-go/generator"
43:             v = v.FieldByName(generator.CamelCase(s))

Looks like we have the following breakdown of usage:

• 5 * generator.CamelCase (template.go)
• 4 * generator.CamelCase (types.go)
• 1 * generator.CamelCase (fieldmask_helper.go)

We already have an implementation of CamelCase in [protoc-gen-swagger/genswagger/template.go](https://github.com/grpc-ecosystem/grpc-gateway/pull/1213/files#diff-d419038d63db0fdabc61f0d6cc6683aeR2002). Is there any reason we can't move that implementation into a root levelinternal` package and then just invoke it and remove our dependency entirely?

[johanbrandhorst]

I must've confused it with something else, that sounds straightforward enough.

[eddycjy]

@johanbrandhorst Is there any recent release plan for this issue?

[johanbrandhorst]

We'll make a minor version release soon to get this out :smiley: