types: add Autocomplete utility type (#3479)

Author: Uzlopak

types/dispatcher.d.ts

@@ -6,6 +6,7 @@ import { IncomingHttpHeaders } from './header'
 import BodyReadable from './readable'
 import { FormData } from './formdata'
 import Errors from './errors'
+import { Autocomplete } from './utility'
 
 type AbortSignal = unknown;
 
@@ -234,7 +235,7 @@ declare namespace Dispatcher {
     onBodySent?(chunkSize: number, totalBytesSent: number): void;
   }
   export type PipelineHandler<TOpaque = null> = (data: PipelineHandlerData<TOpaque>) => Readable;
-  export type HttpMethod = 'GET' | 'HEAD' | 'POST' | 'PUT' | 'DELETE' | 'CONNECT' | 'OPTIONS' | 'TRACE' | 'PATCH' | (string & Record<never, never>);
+  export type HttpMethod = Autocomplete<'GET' | 'HEAD' | 'POST' | 'PUT' | 'DELETE' | 'CONNECT' | 'OPTIONS' | 'TRACE' | 'PATCH'>;
 
   /**
    * @link https://fetch.spec.whatwg.org/#body-mixin

types/header.d.ts

@@ -1,9 +1,11 @@
+import { Autocomplete } from "./utility";
+
 /**
  * The header type declaration of `undici`.
  */
 export type IncomingHttpHeaders = Record<string, string | string[] | undefined>;
 
-type HeaderNames =
+type HeaderNames = Autocomplete<
   | 'Accept'
   | 'Accept-CH'
   | 'Accept-Charset'
@@ -93,60 +95,62 @@ type HeaderNames =
   | 'WWW-Authenticate'
   | 'X-Content-Type-Options'
   | 'X-Frame-Options'
-  | (string & {})
+>
+
+type IANARegisteredMimeType = Autocomplete<
+  | 'audio/aac'
+  | 'video/x-msvideo'
+  | 'image/avif'
+  | 'video/av1'
+  | 'application/octet-stream'
+  | 'image/bmp'
+  | 'text/css'
+  | 'text/csv'
+  | 'application/vnd.ms-fontobject'
+  | 'application/epub+zip'
+  | 'image/gif'
+  | 'application/gzip'
+  | 'text/html'
+  | 'image/x-icon'
+  | 'text/calendar'
+  | 'image/jpeg'
+  | 'text/javascript'
+  | 'application/json'
+  | 'application/ld+json'
+  | 'audio/x-midi'
+  | 'audio/mpeg'
+  | 'video/mp4'
+  | 'video/mpeg'
+  | 'audio/ogg'
+  | 'video/ogg'
+  | 'application/ogg'
+  | 'audio/opus'
+  | 'font/otf'
+  | 'application/pdf'
+  | 'image/png'
+  | 'application/rtf'
+  | 'image/svg+xml'
+  | 'image/tiff'
+  | 'video/mp2t'
+  | 'font/ttf'
+  | 'text/plain'
+  | 'application/wasm'
+  | 'video/webm'
+  | 'audio/webm'
+  | 'image/webp'
+  | 'font/woff'
+  | 'font/woff2'
+  | 'application/xhtml+xml'
+  | 'application/xml'
+  | 'application/zip'
+  | 'video/3gpp'
+  | 'video/3gpp2'
+  | 'model/gltf+json'
+  | 'model/gltf-binary'
+>
 
 type KnownHeaderValues = {
-  'content-type':
-    | 'audio/aac'
-    | 'video/x-msvideo'
-    | 'image/avif'
-    | 'video/av1'
-    | 'application/octet-stream'
-    | 'image/bmp'
-    | 'text/css'
-    | 'text/csv'
-    | 'application/vnd.ms-fontobject'
-    | 'application/epub+zip'
-    | 'image/gif'
-    | 'application/gzip'
-    | 'text/html'
-    | 'image/x-icon'
-    | 'text/calendar'
-    | 'image/jpeg'
-    | 'text/javascript'
-    | 'application/json'
-    | 'application/ld+json'
-    | 'audio/x-midi'
-    | 'audio/mpeg'
-    | 'video/mp4'
-    | 'video/mpeg'
-    | 'audio/ogg'
-    | 'video/ogg'
-    | 'application/ogg'
-    | 'audio/opus'
-    | 'font/otf'
-    | 'application/pdf'
-    | 'image/png'
-    | 'application/rtf'
-    | 'image/svg+xml'
-    | 'image/tiff'
-    | 'video/mp2t'
-    | 'font/ttf'
-    | 'text/plain'
-    | 'application/wasm'
-    | 'video/webm'
-    | 'audio/webm'
-    | 'image/webp'
-    | 'font/woff'
-    | 'font/woff2'
-    | 'application/xhtml+xml'
-    | 'application/xml'
-    | 'application/zip'
-    | 'video/3gpp'
-    | 'video/3gpp2'
-    | 'model/gltf+json'
-    | 'model/gltf-binary'
-    | (string & {})
+  'content-type': IANARegisteredMimeType
 }
 
 export type HeaderRecord = {

types/utility.d.ts

@@ -0,0 +1,7 @@
+type AutocompletePrimitiveBaseType<T> =
+  T extends string ? string :
+  T extends number ? number :
+  T extends boolean ? boolean :
+  never;
+
+export type Autocomplete<T> = T | (AutocompletePrimitiveBaseType<T> & Record<never, never>);