Allow 2 root nodes with v-if and v-else

[chrisvfritz]

Since 2 root nodes with v-if and v-else are guaranteed to return one vnode, they should be considered safe in the root of a template.

[LinusBorg]

You also have to check for the absence of v-for on the element that has v-if, as the combination of both would potentially also result in more than one root element.

Or is that done somewhere else generally?

[chrisvfritz]

@LinusBorg There's a separate warning for v-for on root, which is triggered whether or not a v-if exists.

[LinusBorg]

I saw that but was unsure weither it only applies if there is one root item.

[chrisvfritz]

@LinusBorg Just confirmed with another test locally that this:

<div v-if="1" v-for="i in [1]"></div><div v-else></div>

does indeed warn about v-for, but root constraints were not being applied to the 2nd element with v-else. Added a test for it and fixed the issue. 👍

[chrisvfritz]

It perhaps should be noted that the following will currently NOT trigger a warning:

<p v-if="0"></p>
<p v-else></p>
<p v-else></p>

But I consider this a separate issue, since this doesn't warn in any context, even though it should probably be considered invalid. Also, the above code does still guarantee the return of a single vnode (either the first or last element - the 2nd element is seemingly ignored by the parser).

[yyx990803]

Great job!