grpc: accept interface in NewClient functions (#1025)

* grpc: accept interface in NewClient functions

* fix deprecated.pb.go and grpc_empty.pb.go

* add go.mod and go.sum to testdata/grpc

* remove comment

Makefile

@@ -37,7 +37,7 @@ install:
 test:
 	go test ./... ./protoc-gen-go/testdata
 	go test -tags purego ./... ./protoc-gen-go/testdata
-	go build ./protoc-gen-go/testdata/grpc/grpc.pb.go
+	cd protoc-gen-go/testdata/grpc && go build grpc.pb.go
 
 clean:
 	go clean ./...

protoc-gen-go/grpc/grpc.go

@@ -47,7 +47,7 @@ import (
 // It is incremented whenever an incompatibility between the generated code and
 // the grpc package is introduced; the generated code references
 // a constant, grpc.SupportPackageIsVersionN (where N is generatedCodeVersion).
-const generatedCodeVersion = 4
+const generatedCodeVersion = 6
 
 // Paths for packages used by code generated in this file,
 // relative to the import_prefix of the generator.Generator.
@@ -112,7 +112,7 @@ func (g *grpc) Generate(file *generator.FileDescriptor) {
 
 	g.P("// Reference imports to suppress errors if they are not otherwise used.")
 	g.P("var _ ", contextPkg, ".Context")
-	g.P("var _ ", grpcPkg, ".ClientConn")
+	g.P("var _ ", grpcPkg, ".ClientConnInterface")
 	g.P()
 
 	// Assert version compatibility.
@@ -177,15 +177,15 @@ func (g *grpc) generateService(file *generator.FileDescriptor, service *pb.Servi
 
 	// Client structure.
 	g.P("type ", unexport(servName), "Client struct {")
-	g.P("cc *", grpcPkg, ".ClientConn")
+	g.P("cc ", grpcPkg, ".ClientConnInterface")
 	g.P("}")
 	g.P()
 
 	// NewClient factory.
 	if deprecated {
 		g.P(deprecationComment)
 	}
-	g.P("func New", servName, "Client (cc *", grpcPkg, ".ClientConn) ", servName, "Client {")
+	g.P("func New", servName, "Client (cc ", grpcPkg, ".ClientConnInterface) ", servName, "Client {")
 	g.P("return &", unexport(servName), "Client{cc}")
 	g.P("}")
 	g.P()

protoc-gen-go/testdata/grpc/go.mod

@@ -0,0 +1,10 @@
+module github.com/golang/protobuf/protoc-gen-go/testdata/grpc
+
+go 1.9
+
+require (
+	github.com/golang/protobuf v1.3.2
+	google.golang.org/grpc v1.27.0-pre.0.20200124224931-7afcfdd66b12
+)
+
+replace github.com/golang/protobuf => ../../..

protoc-gen-go/testdata/grpc/go.sum

@@ -0,0 +1,46 @@
+cloud.google.com/go v0.26.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
+github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
+github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
+github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
+github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b h1:VKtxabqXZkF25pY9ekfRL6a582T4P37/31XEstQ5p58=
+github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
+github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
+github.com/google/go-cmp v0.2.0 h1:+dTQ8DZQJz0Mb/HjFlkptS1FeQ4cWSnN941F8aEG4SQ=
+github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
+github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
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