Fix Go feature set handling in editions for checks

This fixes the handling of the Go feature set in editions for use with
checks. Dynamic types would cause the google.golang.org/protobuf
library to panic when trying to fetch the Go feature extension. This is
a temporary workaround until upstream can be resolved. See the issue:
golang/protobuf#1669

When resolving file descriptors for checks, we now check for use of
google/protobuf/go_features.proto and reparse extensions with a resolver
targetted at the gofeaturespb package. This ensure the types will match
the ones set in the extension type gofeaturespb.E_go.

Fixes #3580

private/bufpkg/bufcheck/client.go

@@ -109,7 +109,12 @@ func (c *client) Lint(
 		return err
 	}
 	logRulesConfig(c.logger, config.rulesConfig)
-	files, err := descriptor.FileDescriptorsForProtoFileDescriptors(imageToProtoFileDescriptors(image))
+	protoFileDescriptors, err := imageToProtoFileDescriptors(image)
+	if err != nil {
+		// If a validated Image results in an error, this is a system error.
+		return syserror.Wrap(err)
+	}
+	files, err := descriptor.FileDescriptorsForProtoFileDescriptors(protoFileDescriptors)
 	if err != nil {
 		// If a validated Image results in an error, this is a system error.
 		return syserror.Wrap(err)
@@ -174,12 +179,22 @@ func (c *client) Breaking(
 		return err
 	}
 	logRulesConfig(c.logger, config.rulesConfig)
-	fileDescriptors, err := descriptor.FileDescriptorsForProtoFileDescriptors(imageToProtoFileDescriptors(image))
+	protoFileDescriptors, err := imageToProtoFileDescriptors(image)
+	if err != nil {
+		// If a validated Image results in an error, this is a system error.
+		return syserror.Wrap(err)
+	}
+	fileDescriptors, err := descriptor.FileDescriptorsForProtoFileDescriptors(protoFileDescriptors)
+	if err != nil {
+		// If a validated Image results in an error, this is a system error.
+		return syserror.Wrap(err)
+	}
+	againstProtoFileDescriptors, err := imageToProtoFileDescriptors(againstImage)
 	if err != nil {
 		// If a validated Image results in an error, this is a system error.
 		return syserror.Wrap(err)
 	}
-	againstFileDescriptors, err := descriptor.FileDescriptorsForProtoFileDescriptors(imageToProtoFileDescriptors(againstImage))
+	againstFileDescriptors, err := descriptor.FileDescriptorsForProtoFileDescriptors(againstProtoFileDescriptors)
 	if err != nil {
 		// If a validated Image results in an error, this is a system error.
 		return syserror.Wrap(err)

private/bufpkg/bufcheck/util.go

@@ -15,16 +15,61 @@
 package bufcheck
 
 import (
+	"slices"
+
 	descriptorv1 "buf.build/gen/go/bufbuild/bufplugin/protocolbuffers/go/buf/plugin/descriptor/v1"
 	"github.com/bufbuild/buf/private/bufpkg/bufimage"
+	"github.com/bufbuild/buf/private/pkg/protoencoding"
 	"github.com/bufbuild/buf/private/pkg/slicesext"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/descriptorpb"
 )
 
-func imageToProtoFileDescriptors(image bufimage.Image) []*descriptorv1.FileDescriptor {
+func imageToProtoFileDescriptors(image bufimage.Image) ([]*descriptorv1.FileDescriptor, error) {
 	if image == nil {
-		return nil
+		return nil, nil
+	}
+	descriptors := slicesext.Map(image.Files(), imageToProtoFileDescriptor)
+	// We need to ensure that if a FileDescriptorProto includes a Go
+	// feature set extension, that it matches the runtime version in
+	// gofeaturespb. The runtime will use the gofeaturespb.E_Go extension
+	// type to determine how to parse the file. This must match the expected
+	// go type to avoid panics on getting the extension when using
+	// proto.GetExtension or protodesc.NewFiles. We therefore reparse all
+	// extensions if it may contain any Go feature set extensions.
+	// See the issue: https://github.com/golang/protobuf/issues/1669
+	const goFeaturesImportPath = "google/protobuf/go_features.proto"
+	var reparseDescriptors []*descriptorv1.FileDescriptor
+	for _, descriptor := range descriptors {
+		fileDescriptorProto := descriptor.FileDescriptorProto
+		// Trigger reparsing on any file that includes the gofeatures import.
+		if slices.Contains(fileDescriptorProto.Dependency, goFeaturesImportPath) {
+			reparseDescriptors = append(reparseDescriptors, descriptor)
+		}
+	}
+	if len(reparseDescriptors) == 0 {
+		return descriptors, nil
+	}
+	goFeaturesResolver, err := protoencoding.NewGoFeaturesResolver()
+	if err != nil {
+		return nil, err
+	}
+	resolver := protoencoding.CombineResolvers(
+		goFeaturesResolver,
+		protoencoding.NewLazyResolver(slicesext.Map(descriptors, func(fileDescriptor *descriptorv1.FileDescriptor) *descriptorpb.FileDescriptorProto {
+			return fileDescriptor.FileDescriptorProto
+		})...),
+	)
+	for _, descriptor := range reparseDescriptors {
+		// We clone the FileDescriptorProto to avoid modifying the original.
+		fileDescriptorProto := &descriptorpb.FileDescriptorProto{}
+		proto.Merge(fileDescriptorProto, descriptor.FileDescriptorProto)
+		if err := protoencoding.ReparseExtensions(resolver, fileDescriptorProto.ProtoReflect()); err != nil {
+			return nil, err
+		}
+		descriptor.FileDescriptorProto = fileDescriptorProto
 	}
-	return slicesext.Map(image.Files(), imageToProtoFileDescriptor)
+	return descriptors, nil
 }
 
 func imageToProtoFileDescriptor(imageFile bufimage.ImageFile) *descriptorv1.FileDescriptor {

private/pkg/protoencoding/protoencoding.go

@@ -15,6 +15,8 @@
 package protoencoding
 
 import (
+	"sync"
+
 	"buf.build/go/protoyaml"
 	"github.com/bufbuild/buf/private/pkg/protodescriptor"
 	"google.golang.org/protobuf/proto"
@@ -26,6 +28,13 @@ import (
 // EmptyResolver is a resolver that never resolves any descriptors. All methods will return (nil, NotFound).
 var EmptyResolver Resolver = emptyResolver{}
 
+var (
+	// goFeaturesOnce is used to lazily create goFeaturesValue in NewGoFeaturesResolver.
+	goFeaturesOnce  sync.Once
+	goFeaturesValue *goFeaturesResolver
+	goFeaturesErr   error
+)
+
 // Resolver can resolve files, messages, enums, and extensions.
 type Resolver interface {
 	protodesc.Resolver
@@ -54,6 +63,15 @@ func NewLazyResolver[F protodescriptor.FileDescriptor](fileDescriptors ...F) Res
 	}}
 }
 
+// NewGoFeaturesResolver returns a new Resolver that resolves Go features to
+// the gofeaturespb package.
+func NewGoFeaturesResolver() (Resolver, error) {
+	goFeaturesOnce.Do(func() {
+		goFeaturesValue, goFeaturesErr = newGoFeaturesResolver()
+	})
+	return goFeaturesValue, goFeaturesErr
+}
+
 // CombineResolvers returns a resolver that uses all of the given resolvers. It
 // will use the first resolver, and if it returns an error, the second will be
 // tried, and so on.

private/pkg/protoencoding/reparse_extensions_test.go

@@ -26,9 +26,11 @@ import (
 	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/reflect/protodesc"
 	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoregistry"
 	"google.golang.org/protobuf/testing/protocmp"
 	"google.golang.org/protobuf/types/descriptorpb"
 	"google.golang.org/protobuf/types/dynamicpb"
+	"google.golang.org/protobuf/types/gofeaturespb"
 	"google.golang.org/protobuf/types/known/durationpb"
 	"google.golang.org/protobuf/types/known/timestamppb"
 )
@@ -126,3 +128,66 @@ func TestReparseExtensions(t *testing.T) {
 	})
 	assert.Equal(t, 2, found)
 }
+
+func TestReparseExtensionsGoFeatures(t *testing.T) {
+	t.Parallel()
+
+	goFeaturesMessageDesc := gofeaturespb.File_google_protobuf_go_features_proto.Messages().ByName("GoFeatures")
+	dynamicGoFeatures := dynamicpb.NewMessage(goFeaturesMessageDesc)
+	dynamicGoFeatures.Set(
+		goFeaturesMessageDesc.Fields().ByName("api_level"),
+		protoreflect.ValueOfEnum(gofeaturespb.GoFeatures_API_OPAQUE.Number()),
+	)
+	assert.True(t, dynamicGoFeatures.IsValid())
+	dynamicExt := dynamicpb.NewExtensionType(gofeaturespb.E_Go.TypeDescriptor().Descriptor())
+
+	featureSet := &descriptorpb.FeatureSet{}
+	featureSetReflect := featureSet.ProtoReflect()
+	featureSetReflect.Set(
+		dynamicExt.TypeDescriptor(),
+		protoreflect.ValueOfMessage(dynamicGoFeatures),
+	)
+
+	// Validates the error conditions that cause this panic.
+	// See issue https://github.com/golang/protobuf/issues/1669
+	assert.Panics(t, func() {
+		proto.GetExtension(featureSet, gofeaturespb.E_Go)
+	})
+	descFileDesc, err := protoregistry.GlobalFiles.FindFileByPath("google/protobuf/descriptor.proto")
+	assert.NoError(t, err)
+	goFeaturesFileDesc, err := protoregistry.GlobalFiles.FindFileByPath("google/protobuf/go_features.proto")
+	assert.NoError(t, err)
+	fileDesc := &descriptorpb.FileDescriptorProto{
+		Name: proto.String("a.proto"),
+		Dependency: []string{
+			"google/protobuf/go_features.proto",
+		},
+		Edition: descriptorpb.Edition_EDITION_2023.Enum(),
+		Syntax:  proto.String("editions"),
+		Options: &descriptorpb.FileOptions{
+			Features: featureSet,
+		},
+	}
+	fileSet := &descriptorpb.FileDescriptorSet{
+		File: []*descriptorpb.FileDescriptorProto{
+			protodesc.ToFileDescriptorProto(descFileDesc),
+			protodesc.ToFileDescriptorProto(goFeaturesFileDesc),
+			fileDesc,
+		},
+	}
+	assert.Panics(t, func() {
+		// TODO: if this no longer panics, we can remove the code handling
+		// this workaround in bufcheck.imageToProtoFileDescriptors.
+		_, err := protodesc.NewFiles(fileSet)
+		assert.NoError(t, err)
+	})
+
+	// Run the resvoler to convert the extension.
+	goFeaturesResolver, err := newGoFeaturesResolver()
+	require.NoError(t, err)
+	err = ReparseExtensions(goFeaturesResolver, featureSetReflect)
+	require.NoError(t, err)
+	goFeatures, ok := proto.GetExtension(featureSet, gofeaturespb.E_Go).(*gofeaturespb.GoFeatures)
+	require.True(t, ok)
+	assert.Equal(t, goFeatures.GetApiLevel(), gofeaturespb.GoFeatures_API_OPAQUE)
+}

private/pkg/protoencoding/resolver.go

@@ -22,6 +22,7 @@ import (
 	"google.golang.org/protobuf/reflect/protoreflect"
 	"google.golang.org/protobuf/reflect/protoregistry"
 	"google.golang.org/protobuf/types/dynamicpb"
+	"google.golang.org/protobuf/types/gofeaturespb"
 )
 
 const maxTagNumber = 536870911 // 2^29 - 1
@@ -248,3 +249,34 @@ func (emptyResolver) FindMessageByName(protoreflect.FullName) (protoreflect.Mess
 func (emptyResolver) FindMessageByURL(string) (protoreflect.MessageType, error) {
 	return nil, protoregistry.NotFound
 }
+
+type goFeaturesResolver struct {
+	protoregistry.Files
+	protoregistry.Types
+}
+
+func newGoFeaturesResolver() (*goFeaturesResolver, error) {
+	var protoregistryFiles protoregistry.Files
+	if err := protoregistryFiles.RegisterFile(
+		gofeaturespb.File_google_protobuf_go_features_proto,
+	); err != nil {
+		return nil, err
+	}
+
+	var protoregistryTypes protoregistry.Types
+	if err := protoregistryTypes.RegisterExtension(
+		gofeaturespb.E_Go.TypeDescriptor().Type(),
+	); err != nil {
+		return nil, err
+	}
+	if err := protoregistryTypes.RegisterMessage(
+		(&gofeaturespb.GoFeatures{}).ProtoReflect().Type(),
+	); err != nil {
+		return nil, err
+	}
+
+	return &goFeaturesResolver{
+		Files: protoregistryFiles,
+		Types: protoregistryTypes,
+	}, nil
+}