Svelte 5: Clearer docs on snippet and slots interoperability or lack thereof

[brunnerh]

Describe the problem

The preview docs currently state this regarding slots:

They continue to work, however, and you can mix and match snippets and slots in your components.

This is at least a bit misleading, unless the following should not happen:

• Passing a #snippet to a component using a named <slot /> does not render the snippet content.
• Passing a slotted element or fragment to a component using @render does not render the slot content.

REPL

Describe the proposed solution

• Explain what combinations of snippets and slots work and which do not.
• Deprecate <svelte:fragment> along with <slot>? (Maybe that is already supposed to be implicitly the case. If so, that could be more explicit.)

Importance

nice to have

[rChaoz]

To me, this looks like you can't "mix and match" at all - there doesn't seem to be even a single combination where mixing and matching snippets and slots works, except for children maybe. Is this supposed to be the case? It feels like all of the cases in the REPL above should work, I say this should be a bug not a documentation issue.

Deprecate along with ? (Maybe that is already supposed to be implicitly the case. If so, that could be more explicit.)

I think they shouldn't be deprecated, at least until passing snippets to props is supported, otherwise it's impossible to use Svelte 4 components from Svelte 5 code without deprecation warnings.

[brunnerh]

I'm not suggesting to add a deprecation warning on fragments, you also don't get one on slots (which would be bad since they still need to be used if they are not fully interoperable with snippets).