this.$slots contents differ at same lifecycle stage based on slot syntax

[tehciolo]

Version

2.6.11

Reproduction link

https://codepen.io/tehciolo/pen/zYKaRQK

Steps to reproduce

Check console

What is expected?

I would expect this.$slots to be populated at the same stage for both syntaxes (old and new).

What is actually happening?

this.$slots is populated only starting with mounted when using v-slot syntax

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This issue seems related to #9458

[posva]

This is expected because both syntaxes were different and they are unified only in Vue 3 to avoid breaking changes in Vue 2. More details have been given in similar issues, tldr is: $slots directly contains vnode while $scopedSlots contains functions to create those vnodes, slot="name" uses $slots while v-slot uses $scopedSlots. $slots of scoped slots are only available after mounting when the vnodes have been created. If for some reason the slot is not being rendered (e.g. with a v-if), $slots will stay empy