fix import alias issue with protoc-gen-grpc-gateway

[danielhochman]

Have you read the Contributing Guidelines?

Yes

Brief description of what is fixed or changed

Starting in v2, if any base imports collide with imported packages in the proto, the base import will be aliased and pb.gw.go will not compile. Compilation fails because the rest of the template does not account for the import alias.

Proto file import (whose go_package is google.golang.org/genproto/googleapis/rpc/status):

...
import "google/rpc/status.proto";

message BatchResponse {
  repeated google.rpc.Status statuses = 1;
}

Generated batch.pb.gw.go:

import (
	...
	status_0 "google.golang.org/grpc/status"
	...
)

Build fails.

$ go build
api/v1/batch.pb.gw.go:22:2: imported and not used: "google.golang.org/grpc/status" as status_0
api/v1/batch.pb.gw.go:29:7: undefined: status

The regression occurred as part of the move to v2 because the files are loaded into the registry in v2 before the generator set up base imports in the registry.

Other comments

I'm sure there are many possible fixes here. However, I went ahead and just had the registry returned by the generator New instead of being an input parameter to enforce the call order previously used in v1. Happy to try another approach if this is building on a brittle foundation.

(note: working on getting corp CLA signed)

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[codecov-io]

Codecov Report

Merging #1757 into master will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1757      +/-   ##
==========================================
- Coverage   58.74%   58.73%   -0.02%     
==========================================
  Files          33       33              
  Lines        3624     3625       +1     
==========================================
  Hits         2129     2129              
- Misses       1237     1238       +1     
  Partials      258      258              

Impacted Files	Coverage Δ
...-gen-grpc-gateway/internal/gengateway/generator.go	40.17% <0.00%> (-0.37%)	⬇️

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[johanbrandhorst]

This fix looks fine, and I think it will change in the long term with the work @adambabik is doing in #1756 (:heart:), but I was wondering if we could add a test for this, or a test file that when generated without this fix exhibits the failure?

Thanks again for your contributions!

[johanbrandhorst]

Looks like we'll need to rebase these changes on master since #1752 was merged.

[johanbrandhorst]

Hi Daniel, I just merged #1756 so this will need a rebase, sorry for the inconvenience.

[johanbrandhorst]

Thanks for your contribution!