Name unnamed parameters in function type annotations (#59790)

flow-typed/environment/node.js

@@ -2549,7 +2549,7 @@ declare module 'fs' {
       ...
     }>,
     writeFile(
-      FSPromisePath | FileHandle,
+      v0: FSPromisePath | FileHandle,
       data: string | Buffer | Uint8Array,
       options?: string | WriteOptions,
     ): Promise<void>,
@@ -3343,9 +3343,9 @@ declare module 'perf_hooks' {
     setResourceTimingBufferSize(maxSize: number): void;
     readonly timeOrigin: number;
     timerify<TArgs extends Iterable<unknown>, TReturn>(
-      fn: (...TArgs) => TReturn,
+      fn: (...rest: TArgs) => TReturn,
       options?: Readonly<{histogram?: RecordableHistogram}>,
-    ): (...TArgs) => TReturn;
+    ): (...rest: TArgs) => TReturn;
     toJSON(): unknown;
   }
 
@@ -3537,7 +3537,7 @@ type readline$InterfaceCompleter = (
   | [Array<string>, string]
   | ((
       line: string,
-      ((err: ?Error, data: [Array<string>, string]) => void),
+      v1: (err: ?Error, data: [Array<string>, string]) => void,
     ) => void);
 
 declare class readline$Interface extends events$EventEmitter {
@@ -5630,18 +5630,18 @@ declare class Process extends events$EventEmitter {
   emitWarning(warning: string | Error): void;
   emitWarning(
     warning: string,
-    typeOrCtor: string | ((...empty) => unknown),
+    typeOrCtor: string | ((...rest: empty) => unknown),
   ): void;
   emitWarning(
     warning: string,
     type: string,
-    codeOrCtor: string | ((...empty) => unknown),
+    codeOrCtor: string | ((...rest: empty) => unknown),
   ): void;
   emitWarning(
     warning: string,
     type: string,
     code: string,
-    ctor?: (...empty) => unknown,
+    ctor?: (...rest: empty) => unknown,
   ): void;
   execArgv: Array<string>;
   execPath: string;
@@ -5671,7 +5671,7 @@ declare class Process extends events$EventEmitter {
     },
     rss: () => number,
   };
-  nextTick: <T>(cb: (...T) => unknown, ...T) => void;
+  nextTick: <T>(cb: (...rest: T) => unknown, ...rest: T) => void;
   pid: number;
   platform: string;
   release: {

flow-typed/npm/babel-traverse_v7.x.x.js

@@ -631,7 +631,7 @@ declare module '@babel/traverse' {
 
     constructor(hub: HubInterface, parent: BabelNode): NodePath<TNode>;
 
-    static get({
+    static get(v: {
       hub: HubInterface,
       parentPath: ?NodePath<>,
       parent: BabelNode,

flow-typed/npm/babel_v7.x.x.js

@@ -387,7 +387,7 @@ declare module '@babel/core' {
     buildCodeFrameError<TError extends Error>(
       node: BabelNode,
       msg: string,
-      Class<TError>,
+      v2: Class<TError>,
     ): TError;
 
     mergeSourceMap(map: _BabelSourceMap): _BabelSourceMap;
@@ -408,7 +408,7 @@ declare module '@babel/core' {
 
     parseShebang(): void;
 
-    makeResult<T>(TransformResult<T>): TransformResult<T>;
+    makeResult<T>(v: TransformResult<T>): TransformResult<T>;
 
     generate(): TransformResult<>;
   }
@@ -955,8 +955,8 @@ declare module '@babel/core' {
   |};
 
   declare type TransformCallback<TMetadata> =
-    | ((Error, null) => unknown)
-    | ((null, TransformResult<TMetadata> | null) => unknown);
+    | ((v0: Error, v1: null) => unknown)
+    | ((v0: null, v1: TransformResult<TMetadata> | null) => unknown);
 
   /**
    * Transforms the passed in code. Calling a callback with an object with the generated code, source map, and AST.
@@ -1042,7 +1042,8 @@ declare module '@babel/core' {
   declare export function parse(
     code: string,
     options?: BabelCoreOptions,
-    callback: ((error: Error) => void) | ((void, BabelNodeFile) => void),
+    callback:
+      ((error: Error) => void) | ((v0: void, v1: BabelNodeFile) => void),
   ): void;
 
   declare export function parseSync(
@@ -1096,8 +1097,8 @@ declare module '@babel/core' {
   declare export function loadOptions(
     options?: unknown,
     callback:
-      | ((error: Error, null) => unknown)
-      | ((null, config: ResolvedConfig | null) => unknown),
+      | ((error: Error, v1: null) => unknown)
+      | ((v0: null, config: ResolvedConfig | null) => unknown),
   ): void;
   declare export function loadOptionsSync(
     options?: unknown,
@@ -1125,8 +1126,8 @@ declare module '@babel/core' {
   declare export function loadPartialConfig(
     options?: unknown,
     callback:
-      | ((error: Error, null) => unknown)
-      | ((null, config: PartialConfig | null) => unknown),
+      | ((error: Error, v1: null) => unknown)
+      | ((v0: null, config: PartialConfig | null) => unknown),
   ): void;
   declare export function loadPartialConfigSync(
     options?: unknown,
@@ -1314,10 +1315,13 @@ declare module '@babel/template' {
     (opts: PublicOpts): TemplateBuilder<T>,
 
     // Building from a string produces an AST builder function by default.
-    (tpl: string, opts: ?PublicOpts): (?PublicReplacements) => T,
+    (tpl: string, opts: ?PublicOpts): (v: ?PublicReplacements) => T,
 
     // Building from a template literal produces an AST builder function by default.
-    (tpl: Array<string>, ...args: Array<unknown>): (?PublicReplacements) => T,
+    (
+      tpl: Array<string>,
+      ...args: Array<unknown>
+    ): (v: ?PublicReplacements) => T,
 
     // Allow users to explicitly create templates that produce ASTs, skipping
     // the need for an intermediate function.
@@ -1350,13 +1354,13 @@ declare module '@babel/template' {
     (
       tpl: string,
       opts: ?PublicOpts,
-    ): (?PublicReplacements) => Statement | Array<Statement>,
+    ): (v: ?PublicReplacements) => Statement | Array<Statement>,
 
     // Building from a template literal produces an AST builder function by default.
     (
       tpl: Array<string>,
       ...args: Array<unknown>
-    ): (?PublicReplacements) => Statement | Array<Statement>,
+    ): (v: ?PublicReplacements) => Statement | Array<Statement>,
 
     // Allow users to explicitly create templates that produce ASTs, skipping
     // the need for an intermediate function.

flow-typed/npm/base64-js_v1.x.x.js

@@ -5,8 +5,8 @@
 
 declare module 'base64-js' {
   declare module.exports: {
-    byteLength: string => number,
-    fromByteArray: (Uint8Array | Array<number>) => string,
-    toByteArray: string => Uint8Array,
+    byteLength: (v: string) => number,
+    fromByteArray: (v: Uint8Array | Array<number>) => string,
+    toByteArray: (v: string) => Uint8Array,
   };
 }

flow-typed/npm/jest.js

@@ -1191,9 +1191,9 @@ type JestPrettyFormatColors = {
   ...
 };
 
-type JestPrettyFormatIndent = string => string;
+type JestPrettyFormatIndent = (v: string) => string;
 type JestPrettyFormatRefs = Array<any>;
-type JestPrettyFormatPrint = any => string;
+type JestPrettyFormatPrint = (v: any) => string;
 type JestPrettyFormatStringOrNull = string | null;
 
 type JestPrettyFormatOptions = {
@@ -1224,7 +1224,7 @@ type JestPrettyFormatPlugin = {
     opts: JestPrettyFormatOptions,
     colors: JestPrettyFormatColors,
   ) => string,
-  test: any => boolean,
+  test: (v: any) => boolean,
   ...
 };
 

flow-typed/npm/node-fetch_v2.x.x.js

@@ -60,7 +60,8 @@ declare module 'node-fetch' {
     signal?: AbortSignal | null,
 
     // node-fetch extensions
-    agent?: (URL => http.Agent | https.Agent) | http.Agent | https.Agent | null,
+    agent?:
+      ((v: URL) => http.Agent | https.Agent) | http.Agent | https.Agent | null,
     compress?: boolean,
     follow?: number,
     size?: number,

flow-typed/npm/promise_v8.x.x.js

@@ -21,8 +21,8 @@ declare module 'promise/setimmediate/rejection-tracking' {
       options?: ?{
         whitelist?: ?Array<unknown>,
         allRejections?: ?boolean,
-        onUnhandled?: ?(number, unknown) => void,
-        onHandled?: ?(number, unknown) => void,
+        onUnhandled?: ?(v0: number, v1: unknown) => void,
+        onHandled?: ?(v0: number, v1: unknown) => void,
       },
     ) => void,
     disable: () => void,

flow-typed/npm/stacktrace-parser_v0.1.x.js

@@ -12,6 +12,6 @@ type StackFrame = {
 
 declare module 'stacktrace-parser' {
   declare module.exports: {
-    parse: string => Array<StackFrame>,
+    parse: (v: string) => Array<StackFrame>,
   };
 }

flow-typed/npm/ws_v7.x.x.js

@@ -47,34 +47,34 @@ declare class ws$WebSocketServer extends events$EventEmitter {
   /**
    * Emitted when the server closes.
    */
-  on(event: 'close', () => unknown): this;
+  on(event: 'close', v1: () => unknown): this;
 
   /**
    * Emitted when the handshake is complete.
    */
   on(
     event: 'connection',
-    (socket: ws$WebSocket, request: http$IncomingMessage<>) => unknown,
+    v1: (socket: ws$WebSocket, request: http$IncomingMessage<>) => unknown,
   ): this;
 
   /**
    * Emitted when an error occurs on the underlying server.
    */
-  on(event: 'error', (error: Error) => unknown): this;
+  on(event: 'error', v1: (error: Error) => unknown): this;
 
   /**
    * Emitted before the response headers are written to the socket as part of
    * the handshake.
    */
   on(
     event: 'headers',
-    (headers: Array<string>, request: http$IncomingMessage<>) => unknown,
+    v1: (headers: Array<string>, request: http$IncomingMessage<>) => unknown,
   ): this;
 
   /**
    * Emitted when the underlying server has been bound.
    */
-  on(event: 'listening', () => unknown): this;
+  on(event: 'listening', v1: () => unknown): this;
 
   /**
    * Returns the bound address, the address family name, and port of the server
@@ -102,7 +102,7 @@ declare class ws$WebSocketServer extends events$EventEmitter {
     request: http$IncomingMessage<>,
     socket: net$Socket,
     head: Buffer,
-    callback: (?ws$WebSocket) => unknown,
+    callback: (v: ?ws$WebSocket) => unknown,
   ): void;
 
   /**
@@ -137,8 +137,8 @@ declare type ws$MessageListener = (
   isBinary: boolean,
 ) => unknown;
 declare type ws$OpenListener = () => unknown;
-declare type ws$PingListener = (Buffer) => unknown;
-declare type ws$PongListener = (Buffer) => unknown;
+declare type ws$PingListener = (v: Buffer) => unknown;
+declare type ws$PongListener = (v: Buffer) => unknown;
 declare type ws$UnexpectedResponseListener = (
   request: http$ClientRequest<>,
   response: http$IncomingMessage<>,
@@ -173,44 +173,44 @@ declare class ws$WebSocket extends events$EventEmitter {
   /*
    * Emitted when the connection is closed.
    */
-  on('close', ws$CloseListener): this;
+  on(v0: 'close', v1: ws$CloseListener): this;
 
   /*
    * Emitted when an error occurs.
    */
-  on('error', ws$ErrorListener): this;
+  on(v0: 'error', v1: ws$ErrorListener): this;
 
   /*
    * Emitted when a message is received from the server.
    */
-  on('message', ws$MessageListener): this;
+  on(v0: 'message', v1: ws$MessageListener): this;
 
   /*
    * Emitted when the connection is established.
    */
-  on('open', ws$OpenListener): this;
+  on(v0: 'open', v1: ws$OpenListener): this;
 
   /*
    * Emitted when a ping is received from the server.
    */
-  on('ping', ws$PingListener): this;
+  on(v0: 'ping', v1: ws$PingListener): this;
 
   /*
    * Emitted when a pong is received from the server.
    */
-  on('pong', ws$PongListener): this;
+  on(v0: 'pong', v1: ws$PongListener): this;
 
   /*
    * Emitted when the server response is not the expected one,
    * for example a 401 response.
    */
-  on('unexpected-response', ws$UnexpectedResponseListener): this;
+  on(v0: 'unexpected-response', v1: ws$UnexpectedResponseListener): this;
 
   /*
    * Emitted when response headers are received from the server as part of the
    * handshake.
    */
-  on('upgrade', ws$UpgradeListener): this;
+  on(v0: 'upgrade', v1: ws$UpgradeListener): this;
 
   /**
    * Register an event listener emulating the `EventTarget` interface.
@@ -247,7 +247,7 @@ declare class ws$WebSocket extends events$EventEmitter {
   ): this;
   addEventListener(
     type: 'unexpected-response',
-    ws$UnexpectedResponseListener,
+    v1: ws$UnexpectedResponseListener,
     options?: {once?: boolean},
   ): this;
   addEventListener(
@@ -313,7 +313,7 @@ declare class ws$WebSocket extends events$EventEmitter {
   removeEventListener(type: 'pong', listener: ws$PongListener): this;
   removeEventListener(
     type: 'unexpected-response',
-    ws$UnexpectedResponseListener,
+    v1: ws$UnexpectedResponseListener,
   ): this;
   removeEventListener(type: 'upgrade', listener: ws$UpgradeListener): this;
 

packages/dev-middleware/src/inspector-proxy/InspectorProxy.js

@@ -205,7 +205,7 @@ export default class InspectorProxy implements InspectorProxyQueries {
   processRequest(
     request: IncomingMessage,
     response: ServerResponse,
-    next: (?Error) => unknown,
+    next: (v: ?Error) => unknown,
   ) {
     const pathname = new URL(request.url, 'http://example.com').pathname;
     if (

packages/jest-preset/jest/setup.js

@@ -58,7 +58,7 @@ Object.defineProperties(global, {
   requestAnimationFrame: {
     configurable: true,
     enumerable: true,
-    value(callback: number => void): ReturnType<typeof setTimeout> {
+    value(callback: (v: number) => void): ReturnType<typeof setTimeout> {
       return setTimeout(() => callback(jest.now()), 0);
     },
     writable: true,

packages/polyfills/error-guard.js

@@ -12,7 +12,7 @@
 let _inGuard = 0;
 
 type ErrorHandler = (error: unknown, isFatal: boolean) => void;
-type Fn<Args, Return> = (...Args) => Return;
+type Fn<Args, Return> = (...rest: Args) => Return;
 
 /**
  * This is the error handler that is called when we encounter an exception
@@ -98,7 +98,7 @@ const ErrorUtils = {
     fun: Fn<TArgs, TOut>,
     name?: ?string,
     context?: ?unknown,
-  ): ?(...TArgs) => ?TOut {
+  ): ?(...rest: TArgs) => ?TOut {
     // TODO: (moti) T48204753 Make sure this warning is never hit and remove it - types
     // should be sufficient.
     if (typeof fun !== 'function') {