Meta issue: function helper resolution bugs

[dfreeman]

I'm opening this to track issues with function helpers that we expect will be fixed with our planned overhaul of the internal representation of invokable template entities within Glint.

[dfreeman]

unknown is treated as named-args-like

Given this function:

declare function isEqual(a: unknown, b: unknown): boolean;

This will resolve as a helper with one positional arg and shapeless named args.

[dfreeman]

Named-args-like args have to be passed as named args

Given this function:

declare function constructLanguageTag(options: { country: string; language: string }): string;

This should be legal to invoke as either of the following:

{{constructLanguageTag country="US" language="en"}}
{{constructLanguageTag (hash country="US" language="en")}}

However, currently only the former is accepted.

[boris-petrov]

Class args don't work in any way

Given:

class Foo {}
const someFooInstance: Foo;
declare function handleFoo(foo: Foo): string;

This should be legal:

{{handleFoo someFooInstance}}

However, currently there is an error - Expected 0 arguments, but got 1.

[dfreeman]

Not a helper resolution bug, but something we should verify as part of overhauling [Invoke]: we should make sure assignability works as expected with ComponentLike, WithBoundArgs, etc.

As a concrete example, this component:

class MyComponent extends Component<{
  Args: { foo?: string };
  Element: HTMLImageElement;
  Blocks: { default: [] };
}> {}

Should be assignable to (among other things) ComponentLike with no parameters, since it's legal to invoke with no args, ...attributes or blocks.