Denis Migdal comments

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                                            Denis Migdal

Dangerous calls allowed by TS: class generic type, when `unknown`, should be treated as `never` in the class methods/callback parameters

> This is working as intended, because method parameters are bivariant. That's why the "callback" version does result in an error. You can find more information here: https://github.com/microsoft/TypeScript/wiki/FAQ#why-are-function-parameters-bivariant Urg, that's...

Dangerous calls allowed by TS: class generic type, when `unknown`, should be treated as `never` in the class methods/callback parameters

> `{ readonly v: number }` can be passed to `{ v: number }` without issues. The `readonly` only applies to modifications via that interface. WTF. Why ??? That's crazy....

Dangerous calls allowed by TS: class generic type, when `unknown`, should be treated as `never` in the class methods/callback parameters

> So its about the target side requiring more properties than the source has - not about per property modifiers difference Indeed. Still, I don't understand why TS isn't doing...

Dangerous calls allowed by TS: class generic type, when `unknown`, should be treated as `never` in the class methods/callback parameters

> You may also want to join the TypeScript Discord. Maybe I'll do it next time. > * resources are limited. Is a flag check really what is the most...

Dangerous calls allowed by TS: class generic type, when `unknown`, should be treated as `never` in the class methods/callback parameters

I was reading about `in out` annotations in the announcement of 4.7 (couldn't find them in the doc when searching on Google). The initial issue is in fact solved by...

Dangerous calls allowed by TS: class generic type, when `unknown`, should be treated as `never` in the class methods/callback parameters

> `Array` is intentionally covariant because making `Dog[]` not be assignable to `Animal[]` would break a lot of real-world code. A code that would make that is already kind of...

Dangerous calls allowed by TS: class generic type, when `unknown`, should be treated as `never` in the class methods/callback parameters

> @denis-migdal I'm just going to ask that you _please_ not learn TypeScript's various ins and outs via filing bugs on the issue tracker. I'm sorry for that, but you'll...

Dangerous calls allowed by TS: class generic type, when `unknown`, should be treated as `never` in the class methods/callback parameters

> This is, in fact, exactly what happens. The annotations were added later because TS sometimes gets it wrong. When TS gets it wrong on very basic examples... is it...

Dangerous calls allowed by TS: class generic type, when `unknown`, should be treated as `never` in the class methods/callback parameters

> This is a classic invariant case - "represented" as `in out` in TS. This works very much as expected and is correct. If you are after soundness you should,...

Dangerous calls allowed by TS: class generic type, when `unknown`, should be treated as `never` in the class methods/callback parameters

> methods are bivariant in TS. You might not agree with this decision but it's here to stay. And this decision is an example of a design flaw: This produces...