Accept TypeScript type T | null | undefined as a maybe type of T in turbo module (#34158)

Summary:
According Flow's document, a maybe type of T means `T | null | undefined`, instead of `T | null | void`.
I think keeping TypeScript and Flow being consistent to each other is better.

## Changelog

<!-- Help reviewers and the release process by writing your own changelog entry. For an example, see:
https://github.com/facebook/react-native/wiki/Changelog
-->

[General] [Changed] - Accept TypeScript type `T | null | undefined` as a maybe type of T in turbo module.

Pull Request resolved: https://github.com/facebook/react-native/pull/34158

Test Plan: `yarn jest` passed in `packages/react-native-codegen`

Reviewed By: yungsters

Differential Revision: D37731169

Pulled By: philIip

fbshipit-source-id: b6d9b7e8991f60e12c1004bed5b937b34fb02c47

packages/react-native-codegen/src/parsers/typescript/components/__test_fixtures__/failures.js

@@ -141,7 +141,7 @@ import type {ViewProps} from 'ViewPropTypes';
 import type {HostComponent} from 'react-native';
 
 interface NativeCommands {
-  readonly hotspotUpdate: (viewRef: React.Ref<'RCTView'> | null | void, x: Int32, y: Int32) => void;
+  readonly hotspotUpdate: (viewRef: React.Ref<'RCTView'> | null | undefined, x: Int32, y: Int32) => void;
 }
 
 export interface ModuleProps extends ViewProps {
@@ -249,7 +249,7 @@ import type {ViewProps} from 'ViewPropTypes';
 import type {HostComponent} from 'react-native';
 
 export interface ModuleProps extends ViewProps {
-  nullable_with_default: WithDefault<Float, 1.0> | null | void;
+  nullable_with_default: WithDefault<Float, 1.0> | null | undefined;
 }
 
 export default codegenNativeComponent<ModuleProps>(

packages/react-native-codegen/src/parsers/typescript/components/__test_fixtures__/fixtures.js

@@ -15,33 +15,33 @@
 const EVENT_DEFINITION = `
   boolean_required: boolean;
   boolean_optional_key?: boolean;
-  boolean_optional_value: boolean | null | void;
-  boolean_optional_both?: boolean | null | void;
+  boolean_optional_value: boolean | null | undefined;
+  boolean_optional_both?: boolean | null | undefined;
 
   string_required: string;
   string_optional_key?: string;
-  string_optional_value: string | null | void;
-  string_optional_both?: string | null | void;
+  string_optional_value: string | null | undefined;
+  string_optional_both?: string | null | undefined;
 
   double_required: Double;
   double_optional_key?: Double;
-  double_optional_value: Double | null | void;
-  double_optional_both?: Double | null | void;
+  double_optional_value: Double | null | undefined;
+  double_optional_both?: Double | null | undefined;
 
   float_required: Float;
   float_optional_key?: Float;
-  float_optional_value: Float | null | void;
-  float_optional_both?: Float | null | void;
+  float_optional_value: Float | null | undefined;
+  float_optional_both?: Float | null | undefined;
 
   int32_required: Int32;
   int32_optional_key?: Int32;
-  int32_optional_value: Int32 | null | void;
-  int32_optional_both?: Int32 | null | void;
+  int32_optional_value: Int32 | null | undefined;
+  int32_optional_both?: Int32 | null | undefined;
 
   enum_required: 'small' | 'large';
   enum_optional_key?: 'small' | 'large';
-  enum_optional_value: ('small' | 'large') | null | void;
-  enum_optional_both?: ('small' | 'large') | null | void;
+  enum_optional_value: ('small' | 'large') | null | undefined;
+  enum_optional_both?: ('small' | 'large') | null | undefined;
 
   object_required: {
     boolean_required: boolean;
@@ -52,21 +52,21 @@ const EVENT_DEFINITION = `
   };
 
   object_optional_value: {
-    float_optional_value: Float | null | void;
-  } | null | void;
+    float_optional_value: Float | null | undefined;
+  } | null | undefined;
 
   object_optional_both?: {
-    int32_optional_both?: Int32 | null | void;
-  } | null | void;
+    int32_optional_both?: Int32 | null | undefined;
+  } | null | undefined;
 
   object_required_nested_2_layers: {
     object_optional_nested_1_layer?: {
       boolean_required: Int32;
       string_optional_key?: string;
-      double_optional_value: Double | null | void;
-      float_optional_value: Float | null | void;
-      int32_optional_both?: Int32 | null | void;
-    } | null | void;
+      double_optional_value: Double | null | undefined;
+      float_optional_value: Float | null | undefined;
+      int32_optional_both?: Int32 | null | undefined;
+    } | null | undefined;
   };
 
   object_readonly_required: Readonly<{
@@ -78,12 +78,12 @@ const EVENT_DEFINITION = `
   }>;
 
   object_readonly_optional_value: Readonly<{
-    float_optional_value: Float | null | void;
-  }> | null | void;
+    float_optional_value: Float | null | undefined;
+  }> | null | undefined;
 
   object_readonly_optional_both?: Readonly<{
-    int32_optional_both?: Int32 | null | void;
-  }> | null | void;
+    int32_optional_both?: Int32 | null | undefined;
+  }> | null | undefined;
 `;
 
 const ONE_OF_EACH_PROP_EVENT_DEFAULT_AND_OPTIONS = `
@@ -265,43 +265,43 @@ export interface ModuleProps extends ViewProps {
 
   // Object props
   object_optional_key?: Readonly<{prop: string}>;
-  object_optional_both?: Readonly<{prop: string} | null | void>;
-  object_optional_value: Readonly<{prop: string} | null | void>;
+  object_optional_both?: Readonly<{prop: string} | null | undefined>;
+  object_optional_value: Readonly<{prop: string} | null | undefined>;
 
   // ImageSource props
   image_required: ImageSource;
-  image_optional_value: ImageSource | null | void;
-  image_optional_both?: ImageSource | null | void;
+  image_optional_value: ImageSource | null | undefined;
+  image_optional_both?: ImageSource | null | undefined;
 
   // ColorValue props
   color_required: ColorValue;
   color_optional_key?: ColorValue;
-  color_optional_value: ColorValue | null | void;
-  color_optional_both?: ColorValue | null | void;
+  color_optional_value: ColorValue | null | undefined;
+  color_optional_both?: ColorValue | null | undefined;
 
   // ColorArrayValue props
   color_array_required: ColorArrayValue;
   color_array_optional_key?: ColorArrayValue;
-  color_array_optional_value: ColorArrayValue | null | void;
-  color_array_optional_both?: ColorArrayValue | null | void;
+  color_array_optional_value: ColorArrayValue | null | undefined;
+  color_array_optional_both?: ColorArrayValue | null | undefined;
 
   // ProcessedColorValue props
   processed_color_required: ProcessedColorValue;
   processed_color_optional_key?: ProcessedColorValue;
-  processed_color_optional_value: ProcessedColorValue | null | void;
-  processed_color_optional_both?: ProcessedColorValue | null | void;
+  processed_color_optional_value: ProcessedColorValue | null | undefined;
+  processed_color_optional_both?: ProcessedColorValue | null | undefined;
 
   // PointValue props
   point_required: PointValue;
   point_optional_key?: PointValue;
-  point_optional_value: PointValue | null | void;
-  point_optional_both?: PointValue | null | void;
+  point_optional_value: PointValue | null | undefined;
+  point_optional_both?: PointValue | null | undefined;
 
   // EdgeInsets props
   insets_required: EdgeInsetsValue;
   insets_optional_key?: EdgeInsetsValue;
-  insets_optional_value: EdgeInsetsValue | null | void;
-  insets_optional_both?: EdgeInsetsValue | null | void;
+  insets_optional_value: EdgeInsetsValue | null | undefined;
+  insets_optional_both?: EdgeInsetsValue | null | undefined;
 }
 
 export default codegenNativeComponent<ModuleProps>(
@@ -342,32 +342,32 @@ export interface ModuleProps extends ViewProps {
   // Boolean props
   array_boolean_required: ReadonlyArray<boolean>;
   array_boolean_optional_key?: ReadonlyArray<boolean>;
-  array_boolean_optional_value: ReadonlyArray<boolean> | null | void;
-  array_boolean_optional_both?: ReadonlyArray<boolean> | null | void;
+  array_boolean_optional_value: ReadonlyArray<boolean> | null | undefined;
+  array_boolean_optional_both?: ReadonlyArray<boolean> | null | undefined;
 
   // String props
   array_string_required: ReadonlyArray<string>;
   array_string_optional_key?: ReadonlyArray<string>;
-  array_string_optional_value: ReadonlyArray<string> | null | void;
-  array_string_optional_both?: ReadonlyArray<string> | null | void;
+  array_string_optional_value: ReadonlyArray<string> | null | undefined;
+  array_string_optional_both?: ReadonlyArray<string> | null | undefined;
 
   // Double props
   array_double_required: ReadonlyArray<Double>;
   array_double_optional_key?: ReadonlyArray<Double>;
-  array_double_optional_value: ReadonlyArray<Double> | null | void;
-  array_double_optional_both?: ReadonlyArray<Double> | null | void;
+  array_double_optional_value: ReadonlyArray<Double> | null | undefined;
+  array_double_optional_both?: ReadonlyArray<Double> | null | undefined;
 
   // Float props
   array_float_required: ReadonlyArray<Float>;
   array_float_optional_key?: ReadonlyArray<Float>;
-  array_float_optional_value: ReadonlyArray<Float> | null | void;
-  array_float_optional_both?: ReadonlyArray<Float> | null | void;
+  array_float_optional_value: ReadonlyArray<Float> | null | undefined;
+  array_float_optional_both?: ReadonlyArray<Float> | null | undefined;
 
   // Int32 props
   array_int32_required: ReadonlyArray<Int32>;
   array_int32_optional_key?: ReadonlyArray<Int32>;
-  array_int32_optional_value: ReadonlyArray<Int32> | null | void;
-  array_int32_optional_both?: ReadonlyArray<Int32> | null | void;
+  array_int32_optional_value: ReadonlyArray<Int32> | null | undefined;
+  array_int32_optional_both?: ReadonlyArray<Int32> | null | undefined;
 
   // String enum props
   array_enum_optional_key?: WithDefault<
@@ -382,32 +382,32 @@ export interface ModuleProps extends ViewProps {
   // ImageSource props
   array_image_required: ReadonlyArray<ImageSource>;
   array_image_optional_key?: ReadonlyArray<ImageSource>;
-  array_image_optional_value: ReadonlyArray<ImageSource> | null | void;
-  array_image_optional_both?: ReadonlyArray<ImageSource> | null | void;
+  array_image_optional_value: ReadonlyArray<ImageSource> | null | undefined;
+  array_image_optional_both?: ReadonlyArray<ImageSource> | null | undefined;
 
   // ColorValue props
   array_color_required: ReadonlyArray<ColorValue>;
   array_color_optional_key?: ReadonlyArray<ColorValue>;
-  array_color_optional_value: ReadonlyArray<ColorValue> | null | void;
-  array_color_optional_both?: ReadonlyArray<ColorValue> | null | void;
+  array_color_optional_value: ReadonlyArray<ColorValue> | null | undefined;
+  array_color_optional_both?: ReadonlyArray<ColorValue> | null | undefined;
 
   // PointValue props
   array_point_required: ReadonlyArray<PointValue>;
   array_point_optional_key?: ReadonlyArray<PointValue>;
-  array_point_optional_value: ReadonlyArray<PointValue> | null | void;
-  array_point_optional_both?: ReadonlyArray<PointValue> | null | void;
+  array_point_optional_value: ReadonlyArray<PointValue> | null | undefined;
+  array_point_optional_both?: ReadonlyArray<PointValue> | null | undefined;
 
   // EdgeInsetsValue props
   array_insets_required: ReadonlyArray<EdgeInsetsValue>;
   array_insets_optional_key?: ReadonlyArray<EdgeInsetsValue>;
-  array_insets_optional_value: ReadonlyArray<EdgeInsetsValue> | null | void;
-  array_insets_optional_both?: ReadonlyArray<EdgeInsetsValue> | null | void;
+  array_insets_optional_value: ReadonlyArray<EdgeInsetsValue> | null | undefined;
+  array_insets_optional_both?: ReadonlyArray<EdgeInsetsValue> | null | undefined;
 
   // Object props
   array_object_required: ReadonlyArray<Readonly<{prop: string}>>;
   array_object_optional_key?: ReadonlyArray<Readonly<{prop: string}>>;
-  array_object_optional_value: ArrayObjectType | null | void;
-  array_object_optional_both?: ReadonlyArray<ObjectType> | null | void;
+  array_object_optional_value: ArrayObjectType | null | undefined;
+  array_object_optional_both?: ReadonlyArray<ObjectType> | null | undefined;
 
   // Nested array object types
   array_of_array_object_required: ReadonlyArray<
@@ -426,18 +426,18 @@ export interface ModuleProps extends ViewProps {
     Readonly<{
       // This needs to be the same name as the top level array above
       array_object_optional_value: ReadonlyArray<
-        Readonly<{prop: string | null | void}>
+        Readonly<{prop: string | null | undefined}>
       >;
     }>
-  > | null | void;
+  > | null | undefined;
   array_of_array_object_optional_both?: ReadonlyArray<
     Readonly<{
       // This needs to be the same name as the top level array above
       array_object_optional_both: ReadonlyArray<
-        Readonly<{prop?: string | null | void}>
+        Readonly<{prop?: string | null | undefined}>
       >;
     }>
-  > | null | void;
+  > | null | undefined;
 
   // Nested array of array of object types
   array_of_array_of_object_required: ReadonlyArray<
@@ -514,46 +514,46 @@ export interface ModuleProps extends ViewProps {
   // ImageSource props
   image_required: Readonly<{prop: ImageSource}>;
   image_optional_key: Readonly<{prop?: ImageSource}>;
-  image_optional_value: Readonly<{prop: ImageSource | null | void}>;
-  image_optional_both: Readonly<{prop?: ImageSource | null | void}>;
+  image_optional_value: Readonly<{prop: ImageSource | null | undefined}>;
+  image_optional_both: Readonly<{prop?: ImageSource | null | undefined}>;
 
   // ColorValue props
   color_required: Readonly<{prop: ColorValue}>;
   color_optional_key: Readonly<{prop?: ColorValue}>;
-  color_optional_value: Readonly<{prop: ColorValue | null | void}>;
-  color_optional_both: Readonly<{prop?: ColorValue | null | void}>;
+  color_optional_value: Readonly<{prop: ColorValue | null | undefined}>;
+  color_optional_both: Readonly<{prop?: ColorValue | null | undefined}>;
 
   // ProcessedColorValue props
   processed_color_required: Readonly<{prop: ProcessedColorValue}>;
   processed_color_optional_key: Readonly<{prop?: ProcessedColorValue}>;
   processed_color_optional_value: Readonly<{
-    prop: ProcessedColorValue | null | void;
+    prop: ProcessedColorValue | null | undefined;
   }>;
   processed_color_optional_both: Readonly<{
-    prop?: ProcessedColorValue | null | void;
+    prop?: ProcessedColorValue | null | undefined;
   }>;
 
   // PointValue props
   point_required: Readonly<{prop: PointValue}>;
   point_optional_key: Readonly<{prop?: PointValue}>;
-  point_optional_value: Readonly<{prop: PointValue | null | void}>;
-  point_optional_both: Readonly<{prop?: PointValue | null | void}>;
+  point_optional_value: Readonly<{prop: PointValue | null | undefined}>;
+  point_optional_both: Readonly<{prop?: PointValue | null | undefined}>;
 
   // EdgeInsetsValue props
   insets_required: Readonly<{prop: EdgeInsetsValue}>;
   insets_optional_key: Readonly<{prop?: EdgeInsetsValue}>;
-  insets_optional_value: Readonly<{prop: EdgeInsetsValue | null | void}>;
-  insets_optional_both: Readonly<{prop?: EdgeInsetsValue | null | void}>;
+  insets_optional_value: Readonly<{prop: EdgeInsetsValue | null | undefined}>;
+  insets_optional_both: Readonly<{prop?: EdgeInsetsValue | null | undefined}>;
 
   // Nested object props
   object_required: Readonly<{prop: Readonly<{nestedProp: string}>}>;
   object_optional_key?: Readonly<{prop: Readonly<{nestedProp: string}>}>;
   object_optional_value: Readonly<{
     prop: Readonly<{nestedProp: string}>;
-  }> | null | void;
+  }> | null | undefined;
   object_optional_both?: Readonly<{
     prop: Readonly<{nestedProp: string}>;
-  }> | null | void;
+  }> | null | undefined;
 }
 
 export default codegenNativeComponent<ModuleProps>(
@@ -642,20 +642,20 @@ export interface ModuleProps extends ViewProps {
     Readonly<{
       ${EVENT_DEFINITION}
     }>
-  > | null | void;
+  > | null | undefined;
 
   onDirectEventDefinedInlineOptionalBoth?: DirectEventHandler<
     Readonly<{
       ${EVENT_DEFINITION}
     }>
-  > | null | void;
+  > | null | undefined;
 
   onDirectEventDefinedInlineWithPaperName?: DirectEventHandler<
     Readonly<{
       ${EVENT_DEFINITION}
     }>,
     'paperDirectEventDefinedInlineWithPaperName'
-  > | null | void;
+  > | null | undefined;
 
   onBubblingEventDefinedInline: BubblingEventHandler<
     Readonly<{
@@ -673,20 +673,20 @@ export interface ModuleProps extends ViewProps {
     Readonly<{
       ${EVENT_DEFINITION}
     }>
-  > | null | void;
+  > | null | undefined;
 
   onBubblingEventDefinedInlineOptionalBoth?: BubblingEventHandler<
     Readonly<{
       ${EVENT_DEFINITION}
     }>
-  > | null | void;
+  > | null | undefined;
 
   onBubblingEventDefinedInlineWithPaperName?: BubblingEventHandler<
     Readonly<{
       ${EVENT_DEFINITION}
     }>,
     'paperBubblingEventDefinedInlineWithPaperName'
-  > | null | void;
+  > | null | undefined;
 }
 
 export default codegenNativeComponent<ModuleProps>(
@@ -718,21 +718,21 @@ export interface ModuleProps extends ViewProps {
   // Events defined inline
   onDirectEventDefinedInlineNull: DirectEventHandler<null>;
   onDirectEventDefinedInlineNullOptionalKey?: DirectEventHandler<null>;
-  onDirectEventDefinedInlineNullOptionalValue: DirectEventHandler<null> | null | void;
+  onDirectEventDefinedInlineNullOptionalValue: DirectEventHandler<null> | null | undefined;
   onDirectEventDefinedInlineNullOptionalBoth?: DirectEventHandler<null>;
   onDirectEventDefinedInlineNullWithPaperName?: DirectEventHandler<
     null,
     'paperDirectEventDefinedInlineNullWithPaperName'
-  > | null | void;
+  > | null | undefined;
 
   onBubblingEventDefinedInlineNull: BubblingEventHandler<null>;
   onBubblingEventDefinedInlineNullOptionalKey?: BubblingEventHandler<null>;
-  onBubblingEventDefinedInlineNullOptionalValue: BubblingEventHandler<null> | null | void;
-  onBubblingEventDefinedInlineNullOptionalBoth?: BubblingEventHandler<null> | null | void;
+  onBubblingEventDefinedInlineNullOptionalValue: BubblingEventHandler<null> | null | undefined;
+  onBubblingEventDefinedInlineNullOptionalBoth?: BubblingEventHandler<null> | null | undefined;
   onBubblingEventDefinedInlineNullWithPaperName?: BubblingEventHandler<
     null,
     'paperBubblingEventDefinedInlineNullWithPaperName'
-  > | null | void;
+  > | null | undefined;
 }
 
 export default codegenNativeComponent<ModuleProps>(

packages/react-native-codegen/src/parsers/typescript/components/events.js

@@ -89,17 +89,17 @@ function getPropertyType(
       };
 
     case 'TSUnionType':
-      // Check for <T | null | void>
+      // Check for <T | null | undefined>
       if (
         typeAnnotation.types.some(
-          t => t.type === 'TSNullKeyword' || t.type === 'TSVoidKeyword',
+          t => t.type === 'TSNullKeyword' || t.type === 'TSUndefinedKeyword',
         )
       ) {
         const optionalType = typeAnnotation.types.filter(
-          t => t.type !== 'TSNullKeyword' && t.type !== 'TSVoidKeyword',
+          t => t.type !== 'TSNullKeyword' && t.type !== 'TSUndefinedKeyword',
         )[0];
 
-        // Check for <(T | T2) | null | void>
+        // Check for <(T | T2) | null | undefined>
         if (optionalType.type === 'TSParenthesizedType') {
           return getPropertyType(name, true, optionalType.typeAnnotation);
         }
@@ -201,15 +201,15 @@ function buildEventSchema(
   let optional = property.optional || false;
   let typeAnnotation = property.typeAnnotation.typeAnnotation;
 
-  // Check for T | null | void
+  // Check for T | null | undefined
   if (
     typeAnnotation.type === 'TSUnionType' &&
     typeAnnotation.types.some(
-      t => t.type === 'TSNullKeyword' || t.type === 'TSVoidKeyword',
+      t => t.type === 'TSNullKeyword' || t.type === 'TSUndefinedKeyword',
     )
   ) {
     typeAnnotation = typeAnnotation.types.filter(
-      t => t.type !== 'TSNullKeyword' && t.type !== 'TSVoidKeyword',
+      t => t.type !== 'TSNullKeyword' && t.type !== 'TSUndefinedKeyword',
     )[0];
     optional = true;
   }

packages/react-native-codegen/src/parsers/typescript/components/props.js

@@ -52,11 +52,11 @@ function getTypeAnnotationForArray(
   if (
     extractedTypeAnnotation.type === 'TSUnionType' &&
     extractedTypeAnnotation.types.some(
-      t => t.type === 'TSNullKeyword' || t.type === 'TSVoidKeyword',
+      t => t.type === 'TSNullKeyword' || t.type === 'TSUndefinedKeyword',
     )
   ) {
     throw new Error(
-      'Nested optionals such as "ReadonlyArray<boolean | null | void>" are not supported, please declare optionals at the top level of value definitions as in "ReadonlyArray<boolean> | null | void"',
+      'Nested optionals such as "ReadonlyArray<boolean | null | void>" are not supported, please declare optionals at the top level of value definitions as in "ReadonlyArray<boolean> | null | undefined"',
     );
   }
 
@@ -452,15 +452,15 @@ function buildPropSchema(
   let typeAnnotation = value;
   let optional = property.optional || false;
 
-  // Check for optional type in union e.g. T | null | void
+  // Check for optional type in union e.g. T | null | undefined
   if (
     typeAnnotation.type === 'TSUnionType' &&
     typeAnnotation.types.some(
-      t => t.type === 'TSNullKeyword' || t.type === 'TSVoidKeyword',
+      t => t.type === 'TSNullKeyword' || t.type === 'TSUndefinedKeyword',
     )
   ) {
     typeAnnotation = typeAnnotation.types.filter(
-      t => t.type !== 'TSNullKeyword' && t.type !== 'TSVoidKeyword',
+      t => t.type !== 'TSNullKeyword' && t.type !== 'TSUndefinedKeyword',
     )[0];
     optional = true;
 
@@ -483,13 +483,14 @@ function buildPropSchema(
     optional = true;
   }
 
-  // example: Readonly<{prop: string} | null | void>;
+  // example: Readonly<{prop: string} | null | undefined>;
   if (
     value.type === 'TSTypeReference' &&
     typeAnnotation.typeParameters?.params[0].type === 'TSUnionType' &&
     typeAnnotation.typeParameters?.params[0].types.some(
       element =>
-        element.type === 'TSNullKeyword' || element.type === 'TSVoidKeyword',
+        element.type === 'TSNullKeyword' ||
+        element.type === 'TSUndefinedKeyword',
     )
   ) {
     optional = true;

packages/react-native-codegen/src/parsers/typescript/modules/__test_fixtures__/failures.js

@@ -148,11 +148,11 @@ import type {TurboModule} from '../RCTExport';
 import * as TurboModuleRegistry from '../TurboModuleRegistry';
 
 export interface Spec extends TurboModule {
-  readonly getSth: (a: number | null | void) => void;
+  readonly getSth: (a: number | null | undefined) => void;
 }
 
 export interface Spec2 extends TurboModule {
-  readonly getSth: (a: number | null | void) => void;
+  readonly getSth: (a: number | null | undefined) => void;
 }
 `;
 

packages/react-native-codegen/src/parsers/typescript/modules/__test_fixtures__/fixtures.js

@@ -84,7 +84,7 @@ export interface Spec extends TurboModule {
       major: number;
       minor: number;
       patch?: number;
-      prerelease: number | null | void;
+      prerelease: number | null | undefined;
     };
     forceTouchAvailable: boolean;
     osVersion: string;
@@ -295,7 +295,7 @@ import type {TurboModule} from 'react-native/Libraries/TurboModule/RCTExport';
 import * as TurboModuleRegistry from 'react-native/Libraries/TurboModule/TurboModuleRegistry';
 
 export interface Spec extends TurboModule {
-  readonly voidFunc: (arg: string | null | void) => void;
+  readonly voidFunc: (arg: string | null | undefined) => void;
 }
 
 export default TurboModuleRegistry.getEnforcing<Spec>('SampleTurboModule');

packages/react-native-codegen/src/parsers/typescript/utils.js

@@ -75,15 +75,15 @@ function resolveTypeAnnotation(
   };
 
   for (;;) {
-    // Check for optional type in union e.g. T | null | void
+    // Check for optional type in union e.g. T | null | undefined
     if (
       node.type === 'TSUnionType' &&
       node.types.some(
-        t => t.type === 'TSNullKeyword' || t.type === 'TSVoidKeyword',
+        t => t.type === 'TSNullKeyword' || t.type === 'TSUndefinedKeyword',
       )
     ) {
       node = node.types.filter(
-        t => t.type !== 'TSNullKeyword' && t.type !== 'TSVoidKeyword',
+        t => t.type !== 'TSNullKeyword' && t.type !== 'TSUndefinedKeyword',
       )[0];
       nullable = true;
     } else if (node.type === 'TSTypeReference') {