From e389a172f1e9168f892bc2a600e65bff35c2de85 Mon Sep 17 00:00:00 2001
From: yoheimuta <yoheimuta@gmail.com>
Date: Tue, 3 May 2022 14:15:29 +0900
Subject: [PATCH 1/2] feat: Signal proto3 optional support

---
 internal/cmd/protocgenprotolint/cmd.go | 27 ++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/internal/cmd/protocgenprotolint/cmd.go b/internal/cmd/protocgenprotolint/cmd.go
index 9225b8c6..d105dc9a 100644
--- a/internal/cmd/protocgenprotolint/cmd.go
+++ b/internal/cmd/protocgenprotolint/cmd.go
@@ -1,9 +1,12 @@
 package protocgenprotolint
 
 import (
+	"bytes"
 	"fmt"
+	"google.golang.org/protobuf/types/pluginpb"
 	"io"
 	"io/ioutil"
+	"os"
 	"strings"
 
 	"github.com/yoheimuta/protolint/internal/cmd/subcmds"
@@ -36,6 +39,12 @@ func Do(
 		return doVersion(stdout)
 	}
 
+	err := signalSupportProto3Optional()
+	if err != nil {
+		_, _ = fmt.Fprintln(stderr, err)
+		return osutil.ExitInternalFailure
+	}
+
 	subCmd, err := newSubCmd(stdin, stdout, stderr)
 	if err != nil {
 		_, _ = fmt.Fprintln(stderr, err)
@@ -44,6 +53,24 @@ func Do(
 	return subCmd.Run()
 }
 
+func signalSupportProto3Optional() error {
+	// supports proto3 field presence
+	// See https://github.com/protocolbuffers/protobuf/blob/cdc11c2d2d314ce0382fe0eaa715e5e0e1270438/docs/implementing_proto3_presence.md#signaling-that-your-code-generator-supports-proto3-optional
+	var supportedFeatures = uint64(pluginpb.CodeGeneratorResponse_FEATURE_PROTO3_OPTIONAL)
+	data, err := proto.Marshal(&protogen.CodeGeneratorResponse{
+		SupportedFeatures: &supportedFeatures,
+	})
+	if err != nil {
+		return err
+	}
+
+	_, err = io.Copy(os.Stdout, bytes.NewReader(data))
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
 func newSubCmd(
 	stdin io.Reader,
 	stdout io.Writer,

From 5defbf65e2de0e4f94d4d8b309ee0ee838f0b35b Mon Sep 17 00:00:00 2001
From: yoheimuta <yoheimuta@gmail.com>
Date: Tue, 3 May 2022 14:20:43 +0900
Subject: [PATCH 2/2] fix: a minor lint error

---
 internal/cmd/protocgenprotolint/cmd.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/internal/cmd/protocgenprotolint/cmd.go b/internal/cmd/protocgenprotolint/cmd.go
index d105dc9a..7dbe976d 100644
--- a/internal/cmd/protocgenprotolint/cmd.go
+++ b/internal/cmd/protocgenprotolint/cmd.go
@@ -3,12 +3,13 @@ package protocgenprotolint
 import (
 	"bytes"
 	"fmt"
-	"google.golang.org/protobuf/types/pluginpb"
 	"io"
 	"io/ioutil"
 	"os"
 	"strings"
 
+	"google.golang.org/protobuf/types/pluginpb"
+
 	"github.com/yoheimuta/protolint/internal/cmd/subcmds"
 
 	"github.com/yoheimuta/protolint/internal/cmd/subcmds/lint"