dx(runtime-core): warn on render child nodes in void element

[yangxiuxiu1115]

fix #12136

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	100 kB	38 kB	34.2 kB
vue.global.prod.js	159 kB	57.9 kB	51.4 kB

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	46.9 kB	18.3 kB	16.7 kB
createApp	55 kB	21.3 kB	19.4 kB
createSSRApp	59 kB	23 kB	20.9 kB
defineCustomElement	59.8 kB	22.8 kB	20.8 kB
overall	68.7 kB	26.3 kB	24 kB

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commit: 7b68bf7

[edison1105]

I don't think this is a correct fix.

• Firstly, rendering elements inside an <img> tag is unreasonable.
• Secondly, <img><span>1</span></img>, the internal <span> will be rendered. But <component is="img"><span>1</span></component>, the internal <span> will not be rendered. see Playground

If we really want to solve this issue

• the internal <span> should be rendered. When mounting an element, if it is a void tag, its children should be rendered as sibling nodes. Not sure if this is worth it.
• or, gives a warning if the user tries to render nodes in the void tag

[yangxiuxiu1115]

you're right, hydrate checks shouldn't be skipped no matter what.

[edison1105]

@yangxiuxiu1115
The solution I recommend is to give warnings in the DEV. Both ssr and client, when render the child node to a void tag, give the user a warning.
Note, this only happens in <component is="VOID_TAG">child nodes</component>
Would you like to give it a try?

[yangxiuxiu1115]

sure, I'd love to.