It currently just ignores slot-scope and v-slot. We need to add declared variables by scoped slot in local scope.
<template>
<MyComp v-slot="{ foo }"> <!-- foo will be in local scope -->
<p>{{ foo }}</p> <!-- should not provide error here -->
</MyComp>
</template>
Is my following issue related to this?

This behaviour just started today and I can't figure out why... If this isn't related, let me know and I'll open a new issue.
EDIT: I just noticed that this issue is new w/ 0.19.0, as it isn't present in 0.18.1
Yes.
Also ran into this today.

+1, also getting this issue:

but i use vue 2.5 cant support v-slot
I already made a PR #1210 which supports both v-slot and slot-scope.
I still get an error when I use slot variables for v-bind:class



@mrg0lden
Got the same issue too.
However, the problem doesn't exist if v-slot is used inside the template element, e.g.
<editor-menu-bar
:editor="editor"
>
<template v-slot="{commands, isActive, focused}">
...
</template>
</editor-menu-bar>
I have logged a new issue here: https://github.com/vuejs/vetur/issues/2094
Most helpful comment
I already made a PR #1210 which supports both v-slot and slot-scope.