fix(runtime-core):v-for ref behaves differently under prod and dev #6697

[baiwusanyu-c]

close: #6697

[baiwusanyu-c]

wdyt？ @yyx990803 😂

[LinusBorg]

A better / correct solution would involve reading ref.value in lines 101/102 in order to make it a template dependency in DEV as well (where the ref is only passed via it's string name and thus not being read in line 87).

[LinusBorg]

I don't think this is the right fix. "Options API" refs haven't been reactive in Vue 2 or Vue 3. The only way to get a reactive ref is through using a an actual ref()/reactive() object like in the reported issue.

[baiwusanyu-c]

A better / correct solution would involve reading ref.value in lines 101/102 in order to make it a template dependency in DEV as well (where the ref is only passed via it's string name and thus not being read in line 87).

 } else if (!existing.includes(refValue)) {
              existing.push(refValue)
            }

Do you mean these two lines? Lines 101~102

[yyx990803]

The fix is close - the root cause is that in unmount / already array branches, we are only mutating the refs array, however the array is non-reactive when we get it from the refs object.

When in dev mode or the binding ref is returned from setup(), the existing value should be retrieved from setupState so that it's reactive.

I made the small change to reflect this logic and reused the test.