Support multiple generators

The latest version of protoc-gen-go doesn't support gRPC. Supporting
multiple generators is the way to support gRPC going forward.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

Protobuild.toml

@@ -3,7 +3,7 @@ version = "unstable"
 # Generator defines which generator to go. The default is "go". This will be
 # formatted into the --xxx_out flag provided to protoc. Below, we have an
 # example that selects the ctrd vanity binary.
-# generator = "go"
+# generators = ["go"]
 
 # Plugins allows one to specify one or more plugins for use in generation.
 #

config.go

@@ -27,10 +27,14 @@ import (
 const configVersion = "unstable"
 
 type config struct {
-	Version   string
-	Generator string
-	Plugins   []string
-	Includes  struct {
+	Version    string
+	Generators []string
+
+	// Plugins will be deprecated. It has to be per-Generator setting, but neither protoc-gen-go nor protoc-gen-go-grpc
+	// don't support Plugins. So the refactoring is not worth to do.
+	Plugins []string
+
+	Includes struct {
 		Before   []string
 		Vendored []string
 		Packages []string
@@ -40,9 +44,9 @@ type config struct {
 	Packages map[string]string
 
 	Overrides []struct {
-		Prefixes  []string
-		Generator string
-		Plugins   *[]string
+		Prefixes   []string
+		Generators []string
+		Plugins    *[]string
 
 		// TODO(stevvooe): We could probably support overriding of includes and
 		// package maps, but they don't seem to be as useful. Likely,
@@ -59,7 +63,7 @@ type config struct {
 
 func newDefaultConfig() config {
 	return config{
-		Generator: "go",
+		Generators: []string{"go"},
 		Includes: struct {
 			Before   []string
 			Vendored []string

main.go

@@ -77,9 +77,9 @@ func main() {
 
 	// Index overrides by target import path
 	overrides := map[string]struct {
-		Prefixes  []string
-		Generator string
-		Plugins   *[]string
+		Prefixes   []string
+		Generators []string
+		Plugins    *[]string
 	}{}
 	for _, override := range c.Overrides {
 		for _, prefix := range override.Prefixes {
@@ -166,7 +166,7 @@ func main() {
 		includes = append(includes, c.Includes.After...)
 
 		protoc := protocCmd{
-			Name:       c.Generator,
+			Names:      c.Generators,
 			ImportPath: pkg.GoImportPath,
 			PackageMap: c.Packages,
 			Plugins:    c.Plugins,
@@ -182,8 +182,8 @@ func main() {
 
 		if override, ok := overrides[importDirPath]; ok {
 			// selectively apply the overrides to the protoc structure.
-			if override.Generator != "" {
-				protoc.Name = override.Generator
+			if len(override.Generators) > 0 {
+				protoc.Names = override.Generators
 			}
 
 			if override.Plugins != nil {

protoc.go

@@ -30,12 +30,16 @@ var (
 		{{if $index}}` + string(filepath.ListSeparator) + `{{end -}}
 			{{.}}
 	{{- end -}}
-	{{- if .Descriptors}} --include_imports --descriptor_set_out={{.Descriptors}}{{- end }} --
-	{{- .Name -}}_out={{if .Plugins}}plugins={{- range $index, $plugin := .Plugins -}}
-		{{- if $index}}+{{end}}
-		{{- $plugin}}
+	{{- if .Descriptors}} --include_imports --descriptor_set_out={{.Descriptors}}{{- end -}}
+
+	{{- range $index, $name := .Names }} --{{- $name -}}_out=
+		{{- if $.Plugins}}plugins={{- range $index, $plugin := $.Plugins -}}
+			{{- if $index}}+{{end}}
+			{{- $plugin}}
+		{{- end -}},{{- end -}}
+		import_path={{$.ImportPath}}
 	{{- end -}}
-	,{{- end -}}import_path={{.ImportPath}}
+
 	{{- range $proto, $gopkg := .PackageMap -}},M
 		{{- $proto}}={{$gopkg -}}
 	{{- end -}}
@@ -46,7 +50,7 @@ var (
 
 // protocParams defines inputs to a protoc command string.
 type protocCmd struct {
-	Name        string // backend name
+	Names       []string
 	Includes    []string
 	Plugins     []string
 	Descriptors string

protoc_test.go

@@ -0,0 +1,57 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package main
+
+import "testing"
+
+func TestMkcmd(t *testing.T) {
+	testcases := []struct {
+		name     string
+		cmd      protocCmd
+		expected string
+	}{
+		{
+			name:     "basic",
+			cmd:      protocCmd{Names: []string{"go"}},
+			expected: "protoc -I --go_out=import_path=:",
+		},
+		{
+			name:     "plugin",
+			cmd:      protocCmd{Names: []string{"go"}, Plugins: []string{"grpc"}},
+			expected: "protoc -I --go_out=plugins=grpc,import_path=:",
+		},
+		{
+			name:     "use protoc-gen-go-grpc instead of plugins",
+			cmd:      protocCmd{Names: []string{"go", "go-grpc"}},
+			expected: "protoc -I --go_out=import_path= --go-grpc_out=import_path=:",
+		},
+	}
+	for _, tc := range testcases {
+		t.Run(tc.name, func(subtest *testing.T) {
+			cmd := &tc.cmd
+
+			s, err := cmd.mkcmd()
+			if err != nil {
+				subtest.Fatalf("err must be nil but %+v", err)
+			}
+
+			if s != tc.expected {
+				subtest.Fatalf(`s must be %q, but %q`, tc.expected, s)
+			}
+		})
+	}
+}