Fix abuse of generic type

types/vfile/index.d.ts

@@ -10,26 +10,25 @@
 import * as Unist from 'unist';
 
 declare namespace vfile {
-    type Contents = string | Buffer;
+    type VFileContents = string | Buffer;
 
     interface NodeWithPosition extends Unist.Node {
         position: Unist.Position;
         [key: string]: any;
     }
 
-    interface VFileParamsBase<D> {
-        data?: D;
-        contents?: Contents;
+    interface VFileOptions {
+        contents?: VFileContents;
         path?: string;
         basename?: string;
         stem?: string;
         extname?: string;
         dirname?: string;
         cwd?: string;
+        data?: any;
+        [key: string]: any;
     }
 
-    type VFileParams<C extends {data?: {}}> = VFileParamsBase<C['data']> & C;
-
     /**
      * File-related message describing something at certain position.
      */
@@ -102,12 +101,11 @@ declare namespace vfile {
      */
     type ToString = (encoding?: BufferEncoding) => string;
 
-    interface VFileBase<C extends {data?: {}}> {
+    interface VFile {
         /**
          * @param options If `options` is `string` or `Buffer`, treats it as `{contents: options}`. If `options` is a `VFile`, returns it. All other options are set on the newly created `vfile`.
          */
-        (input?: Contents): VFile<C>;
-        <C>(input?: VFile<C> | VFileParams<C>): VFile<C>;
+        <F extends VFile>(input?: VFileContents | F | VFileOptions): F;
         message: Message;
         fail: Fail;
         info: Info;
@@ -119,7 +117,7 @@ declare namespace vfile {
          * Place to store custom information.
          * It's OK to store custom data directly on the `vfile`, moving it to `data` gives a little more privacy.
          */
-        data: C['data'];
+        data: any;
         /**
          * List of messages associated with the file.
          */
@@ -127,7 +125,7 @@ declare namespace vfile {
         /**
          * Raw value.
          */
-        contents: Contents;
+        contents: VFileContents;
         /**
          * Path of `vfile`.
          * Cannot be nullified.
@@ -161,8 +159,6 @@ declare namespace vfile {
         cwd: string;
         toString: ToString;
     }
-
-    type VFile<C> = VFileBase<C> & C;
 }
 
 /**
@@ -170,6 +166,6 @@ declare namespace vfile {
  * Path related properties are set in the following order (least specific to most specific): `history`, `path`, `basename`, `stem`, `extname`, `dirname`.
  * It’s not possible to set either `dirname` or `extname` without setting either `history`, `path`, `basename`, or `stem` as well.
  */
-declare const vfile: vfile.VFile<{}>;
+declare const vfile: vfile.VFile;
 
 export = vfile;

types/vfile/vfile-tests.ts

@@ -1,4 +1,4 @@
-import vfile = require("vfile");
+import vfile = require('vfile');
 import * as Unist from 'unist';
 
 // Instantiation
@@ -7,21 +7,30 @@ vfile('string');
 vfile(Buffer.from('string'));
 vfile(vfile());
 vfile({ stem: 'readme', extname: '.md' });
-vfile({ custom: 'data' });
 try {
     vfile({ extname: '.md' });
 } catch (e) {
     console.log('Error: set extname without path');
 }
 
-const file = vfile<{custom: string, data: {custom: number}}>({
+interface CustomVFile extends vfile.VFile {
+    custom: string;
+    data: {
+        custom: number;
+    };
+}
+
+const file = vfile<CustomVFile>({
     path: '~/example.txt',
     contents: 'Alpha *braavo* charlie.',
     custom: 'Custom tango',
     data: {
         custom: 12345
-    },
+    }
 });
+const customIsString: string = file.custom;
+const dataCustomIsNumber: number = file.data.custom;
+const copiedFile: CustomVFile = vfile(file);
 
 file.path; // => '~/example.txt'
 file.dirname; // => '~'