Pass arbitrary properties to slot

[SeanAllanMacKay]

Is your feature request related to a problem? Please describe.
I have run into cases where it would be nice to be able to pass arbitrary props to a slot, similar to the ability to spread the $$props global over a regular component.

A specific use case was having a generic link wrapper that would wrap any arbitrary components, which would require passing through all properties without knowing what could be present. The consuming component would know what would be present, but not the wrapper itself.

Trying to spread properties over a slot results in a <slot> cannot have directives error

Describe the solution you'd like
I would like to see a way to pass through arbitrary properties to slot components. The first idea that comes to mind is allowing the spreading of props over a slot.

<slot {...$$props} />

Describe alternatives you've considered
As an alternative I have written component specific wrappers rather than generic wrappers.

How important is this feature to you?
It's more of a nicety than a necessity, but I have encountered situations where this would have been handy on more than one occasion.

[TylerRick]

I have wished for this as well...

[pushkine]

Similarly, it could be useful to have a catch-all for the let: directive

<Component let:$$lets>
    <slot {...$$lets} />
</Component>

[Conduitry]

Version 3.30.0 now lets you use spread props in slots: <slot {...foo} />