Using v-if with v-slot directive cause unnecessary update hook

[nndnha]

Vue version

3.2.40

Link to minimal reproduction

https://sfc.vuejs.org/#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

Steps to reproduce

Open the devtools to see the log messages.

What is expected?

onUpdated shouldn't be called on Comp component.

What is actually happening?

onUpdated is called on both App and Comp.

System Info

No response

Any additional comments?

No response

[liulinboyi]

Because it's DYNAMIC_SLOTS, the function shouldUpdateComponent will return true, the component will update and the lifecycle onUpdated will trigger.

core/packages/runtime-core/src/componentRenderUtils.ts

Lines 345 to 349 in 2a9e9a4

	if (patchFlag & PatchFlags.DYNAMIC_SLOTS) {
	// slot content that references values that might have changed,
	// e.g. in a v-for
	return true
	}

[nndnha]

@SuzumiyaHaku v-if="true" doesn't make sense in any real apps, I used it just to make a short description of the problem and the real problem is something like this

[SuzumiyaHaku]

I think you need the v-memo directive.

<template>
  <h1>{{ counter }}</h1>
  <Comp  v-memo="[showHeader]">
    <template v-if="showHeader" #header>
      Header here
    </template>
  </Comp>
</template>

[nndnha]

@SuzumiyaHaku Thanks for your v-memo suggestion! There is another way to solve this:

<template>
  <h1>{{ counter }}</h1>
  <Comp>
    <template #header>
      <template v-if="showHeader">
         Header here
      </template> 
    </template>
  </Comp>
</template>

The main point of this issue is that I think the combination of v-if and v-slot in this case surely is a performance pitfall so we either fix it, or we should at least mention it to the docs.