Spread properties suppress a11y warnings.

[ykrods]

Describe the bug

I noticed that when I use spread properties, I am not warned if I set onclick to an element that is not appropriate.

Example:

<!-- Comp.svelte -->
<script>
  let props = $props()
</script>
<!-- Warned as expected -->
<div onclick={props.onclick}>btn1</div>
<!-- Not warned -->
<div {...props}>btn2</div>

<!-- App.svelte -->
<script>
  import Comp from "./Comp.svelte"
</script>
<Comp onclick={()=> console.log("click")}></Comp>

Expected Logs:

Visible, non-interactive elements with a click event must be accompanied by a keyboard event handler. Consider whether an interactive element such as <button type="button"> or <a> might be more appropriate
  https://svelte.dev/e/a11y_click_events_have_key_events (a11y_click_events_have_key_events)
<div> with a click handler must have an ARIA role
  https://svelte.dev/e/a11y_no_static_element_interactions (a11y_no_static_element_interactions)

Reproduction

https://svelte.dev/playground/f5718f8d68974d49a65489872a064640?version=5.19.9

Logs

N/A

System Info

System:
    OS: macOS 15.3
    CPU: (10) arm64 Apple M4
    Memory: 829.08 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 23.7.0 - /opt/homebrew/bin/node
    npm: 10.9.2 - /opt/homebrew/bin/npm
  Browsers:
    Chrome: 132.0.6834.162
    Safari: 18.3

Severity

annoyance

[Ocean-OS]

The reason for that is that to save bytes Svelte doesn't warn during runtime about a11y. If we were to try to check for this in the compiler, it'd take a lot more code just to be able to "know" if spread props could possibly contain certain properties.

[Conduitry]

Yeah, this is as intended for now. I can imagine us potentially introducing dev-only runtime a11y checks - but that would be its own feature to consider. In the meantime, a11y checks are compile-time, and there's not a good way to know that this spread is going to include an onclick attribute.