Improve support for go_package option in .proto files

protoc-gen-twirp/command_line.go

@@ -21,6 +21,7 @@ import (
 type commandLineParams struct {
 	importPrefix string            // String to prefix to imported package file names.
 	importMap    map[string]string // Mapping from .proto file name to import path.
+	paths        string            // Paths value, used to control file output directory
 }
 
 // parseCommandLineParams breaks the comma-separated list of key=value pairs
@@ -56,6 +57,11 @@ func parseCommandLineParams(parameter string) (*commandLineParams, error) {
 			clp.importMap[k[1:]] = v // 1 is the length of 'M'.
 		case len(k) > 0 && strings.HasPrefix(k, "go_import_mapping@"):
 			clp.importMap[k[18:]] = v // 18 is the length of 'go_import_mapping@'.
+		case k == "paths":
+			if v != "source_relative" {
+				return nil, fmt.Errorf("paths does not support %q", v)
+			}
+			clp.paths = v
 		default:
 			return nil, fmt.Errorf("unknown parameter %q", k)
 		}

protoc-gen-twirp/generator.go

@@ -47,6 +47,9 @@ type twirp struct {
 	importPrefix string            // String to prefix to imported package file names.
 	importMap    map[string]string // Mapping from .proto file name to import path.
 
+	// Package output:
+	sourceRelativePaths bool // instruction on where to write output files
+
 	// Package naming:
 	genPkgName          string // Name of the package that we're generating
 	fileToGoPackageName map[*descriptor.FileDescriptorProto]string
@@ -82,6 +85,8 @@ func (t *twirp) Generate(in *plugin.CodeGeneratorRequest) *plugin.CodeGeneratorR
 
 	t.genFiles = gen.FilesToGenerate(in)
 
+	t.sourceRelativePaths = params.paths == "source_relative"
+
 	// Collect information on types.
 	t.reg = typemap.New(in.ProtoFile)
 
@@ -125,7 +130,6 @@ func (t *twirp) Generate(in *plugin.CodeGeneratorRequest) *plugin.CodeGeneratorR
 			t.fileToGoPackageName[f] = alias
 		}
 	}
-
 	// Showtime! Generate the response.
 	resp := new(plugin.CodeGeneratorResponse)
 	for _, f := range t.genFiles {
@@ -211,7 +215,7 @@ func (t *twirp) generate(file *descriptor.FileDescriptorProto) *plugin.CodeGener
 
 	t.generateFileDescriptor(file)
 
-	resp.Name = proto.String(goFileName(file))
+	resp.Name = proto.String(t.goFileName(file))
 	resp.Content = proto.String(t.formattedOutput())
 	t.output.Reset()
 
@@ -269,7 +273,7 @@ func (t *twirp) generateImports(file *descriptor.FileDescriptorProto) {
 	// method. Make sure to import the package of any such message. First, dedupe
 	// them.
 	deps := make(map[string]string) // Map of package name to quoted import path.
-	ourImportPath := path.Dir(goFileName(file))
+	ourImportPath := path.Dir(t.goFileName(file))
 	for _, s := range file.Service {
 		for _, m := range s.Method {
 			defs := []*typemap.MessageDefinition{
@@ -278,16 +282,20 @@ func (t *twirp) generateImports(file *descriptor.FileDescriptorProto) {
 			}
 			for _, def := range defs {
 				// By default, import path is the dirname of the Go filename.
-				importPath := path.Dir(goFileName(def.File))
+				importPath := path.Dir(t.goFileName(def.File))
 				if importPath == ourImportPath {
 					continue
 				}
+				if def.File.GetOptions().GetGoPackage() != "" {
+					importPath = def.File.GetOptions().GetGoPackage()
+				}
 				if substitution, ok := t.importMap[def.File.GetName()]; ok {
 					importPath = substitution
 				}
 				importPath = t.importPrefix + importPath
 				pkg := t.goPackageName(def.File)
 				deps[pkg] = strconv.Quote(importPath)
+
 			}
 		}
 	}
@@ -1015,7 +1023,7 @@ func (t *twirp) generateServerJSONMethod(service *descriptor.ServiceDescriptorPr
 	t.P(`        panic(r)`)
 	t.P(`      }`)
 	t.P(`    }()`)
-	t.P(`    respContent, err = s.`, servName,`.`,methName, `(ctx, reqContent)`)
+	t.P(`    respContent, err = s.`, servName, `.`, methName, `(ctx, reqContent)`)
 	t.P(`  }()`)
 	t.P()
 	t.P(`  if err != nil {`)
@@ -1088,7 +1096,7 @@ func (t *twirp) generateServerProtobufMethod(service *descriptor.ServiceDescript
 	t.P(`        panic(r)`)
 	t.P(`      }`)
 	t.P(`    }()`)
-	t.P(`    respContent, err = s.`, servName,`.`,methName, `(ctx, reqContent)`)
+	t.P(`    respContent, err = s.`, servName, `.`, methName, `(ctx, reqContent)`)
 	t.P(`  }()`)
 	t.P()
 	t.P(`  if err != nil {`)

protoc-gen-twirp/go_naming.go

@@ -65,13 +65,15 @@ func goPackageName(f *descriptor.FileDescriptorProto) (name string, explicit boo
 }
 
 // goFileName returns the output name for the generated Go file.
-func goFileName(f *descriptor.FileDescriptorProto) string {
+func (t *twirp) goFileName(f *descriptor.FileDescriptorProto) string {
 	name := *f.Name
 	if ext := path.Ext(name); ext == ".proto" || ext == ".protodevel" {
 		name = name[:len(name)-len(ext)]
 	}
 	name += ".twirp.go"
-
+	if t.sourceRelativePaths {
+		return name
+	}
 	// Does the file have a "go_package" option? If it does, it may override the
 	// filename.
 	if impPath, _, ok := goPackageOption(f); ok && impPath != "" {