Merge pull request #274 from twitchtv/version_constant_for_backwards_…

…compatibility Add version_constant and check from generated code
twitchtv · Sep 15, 2020 · 01dd2f0 · 01dd2f0
2 parents bc4f4e8 + 995f6b3
commit 01dd2f0
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diff --git a/clientcompat/internal/clientcompat/clientcompat.twirp.go b/clientcompat/internal/clientcompat/clientcompat.twirp.go
diff --git a/example/service.twirp.go b/example/service.twirp.go
diff --git a/internal/twirptest/empty_service/empty_service.twirp.go b/internal/twirptest/empty_service/empty_service.twirp.go
diff --git a/internal/twirptest/gogo_compat/service.twirp.go b/internal/twirptest/gogo_compat/service.twirp.go
diff --git a/internal/twirptest/google_protobuf_imports/service.twirp.go b/internal/twirptest/google_protobuf_imports/service.twirp.go
diff --git a/internal/twirptest/importable/importable.twirp.go b/internal/twirptest/importable/importable.twirp.go
diff --git a/internal/twirptest/importer/importer.twirp.go b/internal/twirptest/importer/importer.twirp.go
diff --git a/internal/twirptest/importer_local/importer_local.twirp.go b/internal/twirptest/importer_local/importer_local.twirp.go
diff --git a/internal/twirptest/importmapping/x/x.twirp.go b/internal/twirptest/importmapping/x/x.twirp.go
diff --git a/internal/twirptest/multiple/multiple1.twirp.go b/internal/twirptest/multiple/multiple1.twirp.go
diff --git a/internal/twirptest/multiple/multiple2.twirp.go b/internal/twirptest/multiple/multiple2.twirp.go
diff --git a/internal/twirptest/no_package_name/no_package_name.twirp.go b/internal/twirptest/no_package_name/no_package_name.twirp.go
diff --git a/internal/twirptest/no_package_name_importer/no_package_name_importer.twirp.go b/internal/twirptest/no_package_name_importer/no_package_name_importer.twirp.go
diff --git a/internal/twirptest/proto/proto.twirp.go b/internal/twirptest/proto/proto.twirp.go
diff --git a/internal/twirptest/service.twirp.go b/internal/twirptest/service.twirp.go
diff --git a/internal/twirptest/service_method_same_name/service_method_same_name.twirp.go b/internal/twirptest/service_method_same_name/service_method_same_name.twirp.go
diff --git a/internal/twirptest/snake_case_names/snake_case_names.twirp.go b/internal/twirptest/snake_case_names/snake_case_names.twirp.go
diff --git a/internal/twirptest/source_relative/source_relative.twirp.go b/internal/twirptest/source_relative/source_relative.twirp.go
diff --git a/protoc-gen-twirp/generator.go b/protoc-gen-twirp/generator.go
@@ -223,6 +223,8 @@ func (t *twirp) generate(file *descriptor.FileDescriptorProto) *plugin.CodeGener
 		t.generateUtilImports()
 	}
 
+	t.generateVersionCheck(file)
+
 	// For each service, generate client stubs and server
 	for i, service := range file.Service {
 		t.generateService(file, service, i)
@@ -243,6 +245,14 @@ func (t *twirp) generate(file *descriptor.FileDescriptorProto) *plugin.CodeGener
 	return resp
 }
 
+func (t *twirp) generateVersionCheck(file *descriptor.FileDescriptorProto) {
+	t.P(`// This is a compile-time assertion to ensure that this generated file`)
+	t.P(`// is compatible with the twirp package used in your project.`)
+	t.P(`// A compilation error at this line likely means your copy of the`)
+	t.P(`// twirp package needs to be updated.`)
+	t.P(`const _ = `, t.pkgs["twirp"], `.TwirpPackageIsVersion7`)
+}
+
 func (t *twirp) generateFileHeader(file *descriptor.FileDescriptorProto) {
 	t.P("// Code generated by protoc-gen-twirp ", gen.Version, ", DO NOT EDIT.")
 	t.P("// source: ", file.GetName())

diff --git a/version_constant.go b/version_constant.go
@@ -0,0 +1,19 @@
+// Copyright 2018 Twitch Interactive, Inc.  All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"). You may not
+// use this file except in compliance with the License. A copy of the License is
+// located at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// or in the "license" file accompanying this file. This file 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 twirp
+
+// TwirpPackageIsVersion7 is a constant referenced from generated code that
+// requires features on this version of the twirp package. Older versions
+// don't have this constant defined, causing a compile-time assetion error.
+const TwirpPackageIsVersion7 = true