Enable @typescript-eslint/no-redundant-type-constituents rule

[JLHwung]

Q	A
License	MIT

This PR is based on #15793, which also fixes some errors reported by the no-redundant-type-constituents rule. Please review that PR first.

Summary of changes:

• Introduce an API type parameter to the UnloadedDescriptor. It also makes it easier to track preset descriptor vs. plugin descriptor, which ensures that we are not passing incorrect API set to the descriptor.
• Actually types the output source map, previously it is stubbed as any.
• Fixes other errors

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/54905/

[JLHwung]

This cast is unfortunate because the EncodedSourceMap in trace-mapping

export interface SourceMapV3 {
    file?: string | null;
    names: string[];
    sourceRoot?: string;
    sources: (string | null)[];
    sourcesContent?: (string | null)[];
    version: 3;
}
export interface EncodedSourceMap extends SourceMapV3 {
    mappings: string;
}

is slightly different to the one in gen-mapping.

export interface SourceMapV3 {
    file?: string | null;
    names: readonly string[];
    sourceRoot?: string;
    sources: readonly (string | null)[];
    sourcesContent?: readonly (string | null)[];
    version: 3;
}
export interface EncodedSourceMap extends SourceMapV3 {
    mappings: string;
}

[nicolo-ribaudo]

@jridgewell Maybe you want to align them

[nicolo-ribaudo]

We shouldn't use declare here, since the constructor then sets these property (and we do not want to walk the prototype checking if they are already there)

[JLHwung]

I mark them as declare because currently class properties are transpiled to initialization assignments in constructor as we are targeting Node.js 6: https://unpkg.com/@babel/core@7.22.9/lib/transformation/plugin-pass.js, this change will get rid of such extra assignments.

But since we will ship native class properties in Babel 8, I am happy to revert that.

[JLHwung]

I wish I could get rid of the typing cast here, the typeof check here can not rule out {} completely as it could be Function object.

Suggestions are welcome.

[JLHwung]

@ehoogeveen-medweb My bad. I was meant for object as I typed value as an union of object and a specific function:

babel/packages/babel-core/src/config/config-descriptors.ts

Line 38 in 0e20ec5

value: object | ((api: API, options: Options, dirname: string) => unknown);

but for some reason the typeof check does not rule out the object completely.

[ehoogeveen-medweb]

IIRC {} in TypeScript effectively means "anything other than undefined or null", whereas object means "any non-primitive type". Did you want the former or the latter?

Playground example

See also this comment about why {} is included in the default configuration for @typescript-eslint/ban-types.