Svelte5 : melt-ui preprocessor caused `{@const}` values to be used before initialization.

[sparecycles]

Svelte5 : melt-ui preprocessor caused `{@const}` values to be used before initialization.

[dummdidumm]

I think we should preserve the Svelte 4 behavior in legacy mode but introduce the more strict behavior in runes mode (so that we can eventually remove the logic of reordering them)

[AdrianGonz97]

This issue can be boiled down to if the order of @const tag declarations now matter in Svelte 5 and if it's an intended breaking change:

Svelte 4

Svelte 5

[sparecycles]

Svelte4 had too much magic. 😁

There's a third option which is requiring an additional flag for this logic (if it's primarily an issue for library-generated code, since client code can always reorder easily):

Pro

• encourages library developers to support the new rules (rather than tell users to apply the flag), and at the same time
• unblocks the rest of the transition of code to runes for code reliant on broken libraries

Con

• now users will have this flag in their code.
• more compiler modes to test.
• more to document.