Improve babel-core typings

[liuxingbaoyu]

Q	A
License	MIT

See #14601 for more info.

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/52211/

[liuxingbaoyu]

I didn't modify packages\babel-core\src\transformation\util\clone-deep.ts because of #14583.

[liuxingbaoyu]

Seems to be a bug.

[nicolo-ribaudo]

This is probably an array of strings?

[liuxingbaoyu]

I don't know, it's an empty implementation file. But string[] should be fine.

[nicolo-ribaudo]

We can use Parameters<T>[0] and Parameters<T>[1]

[liuxingbaoyu]

It doesn't seem to be, it can't be passed into the Function.

[armano2]

you should be able to use Parameters in here if you define proper correct type of T

i'm not sure what should be in here, but as simple example you can do something like this:

function enhanceError<T extends (arg1?: unknown, arg2?: unknown) => Generator<unknown>>(
  context: ConfigContext,
  fn: T,
): T {
  return function* (arg1: Parameters<T>[0], arg2: Parameters<T>[1]) {

see https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-6.html

[nicolo-ribaudo]

Suggested change

	function chain(a: any, b: any) {
	function chain<Args extends any[])(a: undefined | (...args: Args) => void, b: undefined | (...args: Args) => void) {

and use Args instead of unknown[] below.

[liuxingbaoyu]

export default class Plugin {
  key: string | undefined | null;
  manipulateOptions?: (options: unknown, parserOpts: unknown) => void;
  post?: Function;
  pre?: Function;
  visitor: {};

Pre and post are passed in, and the types do not match. Do I need to modify the Plugin type?

[nicolo-ribaudo]

Todo (for myself): Continue reviewing from this file.

[JLHwung]

Awesome work.

I left some comments about Function. I think it should only be used when we have no idea about its signature, otherwise we'd better explicitly specify its input and output.

[JLHwung]

Can we mark this object as const? So we don't have to add typings at all and TS will infer the typings accordingly.

[liuxingbaoyu]

It doesn't seem to work, the object will be written below.

[JLHwung]

Q: why we need to cast undefined as ValidatedOptions?

[liuxingbaoyu]

Let the type of opts be ValidatedOptions from the function.

[nicolo-ribaudo]

Isn't the opts parameter typed as InputOptions | undefined | null, so undefined should work? 🤔

[liuxingbaoyu]

opts: ValidatedOptions | FileParseCallback
Both ValidatedOptions and FileParseCallback can be undefined.

[JLHwung]

Is it SourceMapConverter from "convert-source-map"?

[liuxingbaoyu]

It seems yes, but there are such definitions in many files.
type SourceMap = any;
I don't know what the reason is.

packages\babel-core\src\transformation\file\generate.ts
packages\babel-core\src\transformation\index.ts
packages\babel-core\src\transformation\file\merge-map.ts

[JLHwung]

type SourceMap = any;

I believe it's a workaround due to lack of typings when we start transitioning to TS.

[JLHwung]

Is it ValidatedOptions from packages/babel-core/src/config/validation/options.ts returned by packages/babel-core/src/transformation/normalize-file.ts? Or should we come up with a new type NormalizedOptions?

[liuxingbaoyu]

Since I'm not familiar enough with babel internals, I can't confirm its type.
Maybe you can take a look after the PR is merged, I didn't change some code that was explicitly defined as any.

CI error is related.

[nicolo-ribaudo]

Future note: we will be able to drop our type definitions for gensync and use DefinitelyTyped/DefinitelyTyped#60125

[nicolo-ribaudo]

Isn't the opts parameter typed as InputOptions | undefined | null, so undefined should work? 🤔

[nicolo-ribaudo]

(also here)

[nicolo-ribaudo]

The linting error looks like a TS bug, I wonder if it's fixed in 4.7.