Remove pointers from trailing slice

private/buf/bufgen/generator.go

@@ -198,30 +198,6 @@ func (g *generator) generateCode(
 	return nil
 }
 
-// hashPluginConfigForImage returns a hash of the plugin config for the image.
-// This is used to batch plugins that have the same configuration.
-// The hash is based on the following properties:
-//   - ExcludeOptions
-//   - Strategy
-//   - RemoteHost
-func hashPluginConfigForImage(pluginConfig bufconfig.GeneratePluginConfig) (string, error) {
-	type imagePluginConfigKey struct {
-		ExcludeOptions []string
-		Strategy       Strategy
-		RemoteHost     string
-	}
-	key := &imagePluginConfigKey{
-		ExcludeOptions: pluginConfig.ExcludeOptions(),
-		Strategy:       Strategy(pluginConfig.Strategy()),
-		RemoteHost:     pluginConfig.RemoteHost(),
-	}
-	bytes, err := json.Marshal(key)
-	if err != nil {
-		return "", err
-	}
-	return string(bytes), nil
-}
-
 func (g *generator) execPlugins(
 	ctx context.Context,
 	container app.EnvStdioContainer,
@@ -235,9 +211,8 @@ func (g *generator) execPlugins(
 	responses := make([]*pluginpb.CodeGeneratorResponse, len(pluginConfigs))
 	requiredFeatures := computeRequiredFeatures(image)
 
-	// Group the pluginConfigs by their hash. The hash only considers the
-	// properties ExcludeOptions, Strategy, and RemoteHost.
-	pluginConfigsForImage, err := slicesext.ToIndexedValuesMapError(pluginConfigs, hashPluginConfigForImage)
+	// Group the pluginConfigs by the properties ExcludeOptions, Strategy, and RemoteHost.
+	pluginConfigsForImage, err := slicesext.ToIndexedValuesMapError(pluginConfigs, createPluginConfigKeyForImage)
 	if err != nil {
 		return nil, err
 	}
@@ -514,3 +489,27 @@ type generateOptions struct {
 func newGenerateOptions() *generateOptions {
 	return &generateOptions{}
 }
+
+// createPluginConfigKeyForImage returns a string of the plugin config with
+// a subset of properties. This is used to batch plugins that have similar
+// configuration. The key is based on the following properties:
+//   - ExcludeOptions
+//   - Strategy
+//   - RemoteHost
+func createPluginConfigKeyForImage(pluginConfig bufconfig.GeneratePluginConfig) (string, error) {
+	type pluginConfigKey struct {
+		ExcludeOptions []string
+		Strategy       Strategy
+		RemoteHost     string
+	}
+	key := &pluginConfigKey{
+		ExcludeOptions: pluginConfig.ExcludeOptions(),
+		Strategy:       Strategy(pluginConfig.Strategy()),
+		RemoteHost:     pluginConfig.RemoteHost(),
+	}
+	bytes, err := json.Marshal(key)
+	if err != nil {
+		return "", err
+	}
+	return string(bytes), nil
+}

private/bufpkg/bufimage/bufimageutil/bufimageutil_test.go

@@ -295,7 +295,7 @@ func TestPackages(t *testing.T) {
 func TestAny(t *testing.T) {
 	t.Parallel()
 	runDiffTest(t, "testdata/any", "c1.txtar", WithIncludeTypes("ExtendedAnySyntax"))
-	runDiffTest(t, "testdata/any", "c2.txtar", WithIncludeTypes("ExtendedAnySyntax_InField")) // c2
+	runDiffTest(t, "testdata/any", "c2.txtar", WithIncludeTypes("ExtendedAnySyntax_InField"))
 	runDiffTest(t, "testdata/any", "c3.txtar", WithIncludeTypes("ExtendedAnySyntax_InList"))
 	runDiffTest(t, "testdata/any", "c4.txtar", WithIncludeTypes("ExtendedAnySyntax_InMap"))
 	runDiffTest(t, "testdata/any", "d.txtar", WithIncludeTypes("NormalMessageSyntaxValidType"))
@@ -388,6 +388,41 @@ func TestTypesFromMainModule(t *testing.T) {
 	assert.ErrorIs(t, err, ErrImageFilterTypeNotFound)
 }
 
+func TestMutateInPlace(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+	_, image, err := getImage(ctx, slogtestext.NewLogger(t), "testdata/options", bufimage.WithExcludeSourceCodeInfo())
+	require.NoError(t, err)
+
+	aProtoFile := image.GetFile("a.proto")
+	aFileDescriptorProto := aProtoFile.FileDescriptorProto()
+	assert.Len(t, aFileDescriptorProto.MessageType, 2) // Foo, Empty
+	assert.Len(t, aFileDescriptorProto.EnumType, 1)    // FooEnum
+	assert.Len(t, aFileDescriptorProto.Service, 1)
+
+	// Shallow copy
+	shallowFilteredImage, err := FilterImage(image, WithIncludeTypes("pkg.Foo"))
+	require.NoError(t, err)
+
+	assert.NotSame(t, aFileDescriptorProto, shallowFilteredImage.GetFile("a.proto").FileDescriptorProto())
+
+	// Mutate in place
+	mutateFilteredImage, err := FilterImage(image, WithIncludeTypes("pkg.Foo"), WithMutateInPlace())
+	require.NoError(t, err)
+
+	// Check that the original image was mutated
+	assert.Same(t, aFileDescriptorProto, mutateFilteredImage.GetFile("a.proto").FileDescriptorProto())
+	assert.Len(t, aFileDescriptorProto.MessageType, 1) // Foo
+	if assert.GreaterOrEqual(t, cap(aFileDescriptorProto.MessageType), 2) {
+		slice := aFileDescriptorProto.MessageType[1:cap(aFileDescriptorProto.MessageType)]
+		for _, elem := range slice {
+			assert.Nil(t, elem) // Empty
+		}
+	}
+	assert.Nil(t, aFileDescriptorProto.EnumType)
+	assert.Nil(t, aFileDescriptorProto.Service)
+}
+
 func getImage(ctx context.Context, logger *slog.Logger, testdataDir string, options ...bufimage.BuildImageOption) (storage.ReadWriteBucket, bufimage.Image, error) {
 	bucket, err := storageos.NewProvider().NewReadWriteBucket(testdataDir)
 	if err != nil {

private/bufpkg/bufimage/bufimageutil/image_filter.go

@@ -621,7 +621,6 @@ func remapSlice[T any](
 			if options.mutateInPlace {
 				newList = list[:toIndex:cap(list)]
 			} else {
-				newList = make([]*T, 0, len(list))
 				newList = append(newList, list[:toIndex]...)
 			}
 		}
@@ -643,6 +642,15 @@ func remapSlice[T any](
 		sourcePathsRemap.markDeleted(sourcePath)
 	}
 	if isDirty {
+		if len(newList) == 0 {
+			return nil, true, nil
+		}
+		if options.mutateInPlace && newList != nil {
+			// Zero out the remaining elements.
+			for i := int(toIndex); i < len(list); i++ {
+				list[i] = nil
+			}
+		}
 		return newList, true, nil
 	}
 	return list, false, nil