Can't access component methods when binding :key on a template

[amrnn90]

Version

3.0.0-rc.10

Reproduction link

https://codesandbox.io/s/happy-fast-vfld6?file=/src/App.vue

Steps to reproduce

Open reproduction link, the code binds :key on a template using a method:

  <template v-for="item in items" :key="itemKey(item)">
    {{item.name}}
  </template>

What is expected?

Should render items normally without throwing an error

What is actually happening?

An error is thrown:

Uncaught ReferenceError: itemKey is not defined

[amrnn90]

@lanezhao
In Vue 3 using key is valid with <template v-for>

[skirtles-code]

It seems the template compiler is generating { key: itemKey(item) } rather than { key: _ctx.itemKey(item) }. That works in function mode but not in module mode.