template inside transition-group children keying

[terenzif]

Version

3.2.26

Reproduction link

sfc.vuejs.org/

Steps to reproduce

Create [transition-group tag="div"]
Put inside a [template v-for="..." ] with required :key
Put inside [template] a [div]
Put inside [template] an iterating [div v-for="..."] with required :key

What is expected?

This should work without warnings

What is actually happening?

It gets the warning:
[TransitionGroup] children must be keyed.

---

Porting a Vue2 component i found the problem dealing with a [template v-for] inside a [transition-group].
The cause is the different key management: [template] don't want keys on its children (they have to be moved inside [template] tag) but [transition-group] still want every children to be keyed.
The result as you can see, is that you receive a warning
[TransitionGroup] children must be keyed.

But if I try to put keys on [transition-group] children (which are actually children of [template]) you get a compile error:
SyntaxError: [template v-for] key should be placed on the [template] tag

[posva]

Duplicate of #4718