// @strict: true
type MyTupleItem = {};
type MyTuple = [MyTupleItem, ...MyTupleItem[]];

type GenericFunction<T extends MyTuple> = (...fromArgs: T) => void;

class GenericClass<T extends MyTuple> {
    from: GenericFunction<T> | undefined;
}

function createClass<T extends MyTuple>(f: GenericFunction<T>): GenericClass<T> {
    return new GenericClass<T>(/* ... use f */);
}

function consumeClass(c: GenericClass<[string, boolean]>) { }

// should work
consumeClass(createClass(str => console.log(str.length)));

// should work
consumeClass(createClass((str, _unused_num) => console.log(str.length)));