Change server to accept both spec compatible and old paths.

protoc-gen-twirp/generator.go

@@ -1067,6 +1067,13 @@ func pathPrefix(file *descriptor.FileDescriptorProto, service *descriptor.Servic
 // pathFor returns the complete path for requests to a particular method on a
 // particular service.
 func pathFor(file *descriptor.FileDescriptorProto, service *descriptor.ServiceDescriptorProto, method *descriptor.MethodDescriptorProto) string {
+	return pathPrefix(file, service) + method.GetName()
+}
+
+// pathForCamelCompat returns the old CamelCase complete path for requests to a
+// particular method on a particular service.
+// This method is here to ensure compatibility with older clients.
+func pathForCamelCompat(file *descriptor.FileDescriptorProto, service *descriptor.ServiceDescriptorProto, method *descriptor.MethodDescriptorProto) string {
 	return pathPrefix(file, service) + stringutils.CamelCase(method.GetName())
 }
 
@@ -1104,8 +1111,13 @@ func (t *twirp) generateServerRouting(servStruct string, file *descriptor.FileDe
 	t.P(`  switch req.URL.Path {`)
 	for _, method := range service.Method {
 		path := pathFor(file, service, method)
+		pathCamel := pathForCamelCompat(file, service, method)
 		methName := "serve" + stringutils.CamelCase(method.GetName())
-		t.P(`  case `, strconv.Quote(path), `:`)
+		caseCondition := strconv.Quote(path)
+		if path != pathCamel {
+			caseCondition += `, ` + strconv.Quote(pathCamel)
+		}
+		t.P(`  case `, caseCondition, `:`)
 		t.P(`    s.`, methName, `(ctx, resp, req)`)
 		t.P(`    return`)
 	}