fix: use fine grained for template if the component is not explicitly in legacy mode

[paoloricciuti]

Closes #16199
Closes #16229
Closes #16194

The ideal would've been to refactor runes from a boolean to an enum but I'll be honest I was quite scared of touching it because there are a bunch of places where we use it and we also move it to other variables...basically if we skip one of this it will break stuff.

So i went for a maybe_runes boolean that checks there's any trace of explicit legacy mode:

• export let
• $$props or $$restProps
• <svelte:options runes={false} />

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🦋 Changeset detected

Latest commit: ed16aa2

The changes in this PR will be included in the next version bump.

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-svelte-16232-svelte.vercel.app/

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Playground

pnpm add https://pkg.pr.new/svelte@16232

[dummdidumm]

Looks good apart from one check

[dummdidumm]

Mhhhm will these tests actually test this correctly? IIRC runtime-runes forces all components to compile in runes mode. Might need some test setup tweaks

[paoloricciuti]

Mhhhm will these tests actually test this correctly? IIRC runtime-runes forces all components to compile in runes mode. Might need some test setup tweaks

Uhm...yeah I think yes...let me change that

[paoloricciuti]

I tweaked the test suite to give precedence to the defined runes option if present, i've also added more tests

[dummdidumm]

Great work!

[gyzerok]

@paoloricciuti does it mean that now I can expect runes mode to be a default until I explicitly enable legacy mode?

[paoloricciuti]

@paoloricciuti does it mean that now I can expect runes mode to be a default until I explicitly enable legacy mode?

Not exactly...this only really applies to the template, since before #16100 reading state in the template of a legacy component would still track said state.

Now if we are not 100% sure the component it's in legacy mode we preserve that behaviour but as soon as you use something that clearly define the mode (like export let or $: or $$props etc) you'll be in legacy mode.

[gyzerok]

Sound great, thank you!