Add option to noExplicitAny which allows it be used in type argument extends clause

[juliusmarminge]

I often find myself disabling the any lint rule for type parameters, would be nice to have an option to the lint rule to allow this usage without disabling the rule everytime manually:

[Conaclos]

Why don't you use unknown?

[juliusmarminge]

Well let's look at this case for example, I'm saying that T extends any function (takes any arguments and can return anything). I am then serializing what the function returns, putting it in a cache. When reading from the cache, I want to deserialize it. With a strongly typed serializer it can look like this:

Changing to unknown, I am now going to get a type-error further down the road:

So let's fix that:

aah crap, now we get new ones. Let's fix those too. Now it looks like the function is good right?

Well now let's add some argument to the functions and we got problems again:

So yea, the only way to get this to work is using any. And even if it would be possible in another way, you have to do a bunch of workarounds that often might end up in an as any...

[Conaclos]

Could you provide a TypeScript playground link of your first code (with any)?

Taking a closer look, I think it is a bad idea to allow this, because it is unsafe, it can lead to runtime errors.
For example:

function withUnstableCache<T extends (args: any[]) => any>(
	f: T,
	args: Parameters<T>,
	tags: CacheTags[],
) {
	f(""); f(0); f([]); // everything is accepted :o
}

I think you could solve the issue by using a type parameter for the function parameters instead of the entire function:

function withUnstableCache<Args extends readonly unknown[]>(
	f: (...args: Args) => unknown,
	args: Args,
	tags: CacheTags[],
) {
	// ...
}

[juliusmarminge]

https://www.typescriptlang.org/play?#code/JYWwDg9gTgLgBAbzgVwHYGcYEMBGAbAUwH0BjLEgCwLgF84AzKCEOAIlQIA8YB6MygqwDcAWABQoSLERwSUAlhgEAKugipaDJi1YxkYQmtTDx4kusxwYRuAF5Z8xSqMAKBDACeYAugBccAG0AXRoASlMxcS4peHMMeABhAEEEgAkAUSJlJIBxAGU7RHE4OCT-VixWcTosdFkLGFExT284BPIqZSwAc0KXFoIIejaUjKzcvNCAgGsCDyGrL0Hh5LTM7PygpqjOGLhaj1QSBjQSGGB1OAB3YBgKAFV43EJ2gQAeYrhlOC4lVAATOouAB0oKwUG6fn2qA8wVCdgAfNCPAAacQIlwQMDWfxIeiofzKIT7CFQgAK4KwIAISig6DeygRxOwkP8r06PWCtHhCE+cUs-Co-wASj5kHh4PYsFcsLcUE98MRBQQXJ8SgcjnAQWDSfDbEjeWISsb6vE4PJ0OLJfsZXKsdZgfjtcDwZDQk0TSV5HooBprOpgegCFBgFg8MAAF4qi1W91q2hoo3G+3oYEs9CJk1IdP+FNpnp1GiZuChZ1513oOORJPe5C+qxGYH-HzB0PhqNvJK2pT-N6in2oZRLBkI0cuZUisUSqs0CL8+D4gCMhQ1xxcWH8mBDqG6KLgOH8qGQIBwwb1SNY9AgEFY+zq87MDQYqAATCv0Ic1yncQxr4fj6eUDcoibA4OCt61KamBzk+FrLlK3bXLcDwKi8HQqoaJQ8DwJQAHoAPyfPi-hLsWFb+AEFSsHuL5BMWOaBKsYwbHkwJJEE1ThNW87mj4b4IbK8A3HcjyYM8BDshhnzYXhhFJsRz4vmRpIUQgV4QP4L40HRnwMQETHrBMbEcWIYQRMUwkoWJiqSW40k4XABFEQSinKaygRqX+oHgdp9EFhRBnjPkxmcRZyGidgNnoXZSYyY5cklAppGfORHnqZpvm6f5jGjIZwXsZxQA

[Conaclos]

What do you think of this refactoring?

[Conaclos]

You could also use never:

function withUnstableCache<T extends (args: never[]) => any>(
	f: T,
	args: Parameters<T>,
	tags: CacheTags[],
) {
	// ...
}

See also this comment for more details.