Make type packs less strict.

[ghost]

There are many built-in functions in Lua that take or return a variadic number of arguments.

For example, lets take unpack. This has the type of ({[any]: any}) -> ...any. The problem with these functions is when we try to work with type packs ontop of them

local t = {t()}
return unpack(t) --Failed to unify generic and variadic type packs

It would be nicer if ...any was permitted as a typepack unification if we're in non-strict mode

[vegorov-rbx]

What is t()?

[ghost]

t() is a function that represents a return typepack, I guess the best way to put it for now is <T...>() -> T...

[zeux]

Could you provide a complete example that generates the error mentioned above?

[ghost]

The issue is mainly when you feed a typepack into a function that takes an any

local function somethingThatsAny(...: any)
	print(...)
end

local function x<T...>(...: T...)
	somethingThatsAny(...) -- Failed to unify variadic type packs
end

I'm ok with T... throwing for more constrained varadics, but in the context where it's any/...any it should be allowed

[zeux]

Thanks! This is helpful and actionable. I don't think we intended for this to happen.