⭐️New: Add vue/no-deprecated-slot-attribute rule

[ota-meshi]

vue/no-deprecated-slot-attribute rule reports deprecated slot attribute in Vue.js v2.6.0+.

<template>
  <ListComponent>
    <!-- ✓ GOOD -->
    <template v-slot:name>
      {{ props.title }}
    </template>
  </ListComponent>
  <ListComponent>
    <!-- ✗ BAD -->
    <template slot="name">
      {{ props.title }}
    </template>
  </ListComponent>
</template>

---

refs #800 (comment)

[mysticatea]

Thank you for this rule!

Almost LGTM, but I have a few suggestions.

[ota-meshi]

Thank you for your review!
I changed this. please check again.

[mysticatea]

LGTM, thank you!

[mysticatea]

I'm sorry, I had overlooked this in the previous review.

[mysticatea]

Hmm, sorry, I had overlooked this in the previous review.

In some cases, slot and v-slot should be in different places.

• v-slot must be on a <template> element which is a direct child of a custom element.
• v-slot for the default slot can be on a custom element directly if there are no named slots.

So in this case, the <a> element must be wrapped by a <template> element.

In the example of nested default slots, it will be moved to the parent element.

Therefore, autofix may be tough to implement... 🤔

[ota-meshi]

Sorry for the late reply.
Thank you for pointing this out.

Sorry, I did not understand v-slot correctly.
I will change it so that it will only autofix if slot is attached to <template>.