fix(types): fix shallowRef type error

[Alfred-Skyblue]

In #7853, a function overload export function shallowRef<T>(value: MaybeRef<T>): Ref<T> | ShallowRef<T> was added. Due to MaybeRef<T> encompassing all types, this resulted in all instances of shallowRef being inferred as Ref<T> | ShallowRef<T>, instead of just ShallowRef<T>.

const res1 = shallowRef(1 as any) // Ref<any> | ShallowRef<any>
const res2 = shallowRef(1) // Ref<number> | ShallowRef<number>
const res3 = shallowRef(ref('foo')) //  Ref<string> | ShallowRef<string>
const res4 = shallowRef({} as MaybeRef<{ name: string }>) // Ref<{name: string}> | ShallowRef<{name: string}>
const res5 = shallowRef('' as string | number) //  Ref<string | number> | ShallowRef<string | number>
const res6 = shallowRef('' as Ref<string[]> | string | number) //  ShallowRef<string | number | Ref<string[]>>

In this PR, I have modified the function overload, resulting in the following types:

const res = shallowRef(1 as any) // ShallowRef<any>
const res1 = shallowRef(1) // ShallowRef<number>
const res2 = shallowRef(ref('foo')) // Ref<string>
const res3 = shallowRef({} as MaybeRef<{ name: string }>) // Ref<{name: string}> | ShallowRef<{name: string}>
const res4 = shallowRef('' as string | number) // ShallowRef<string | number>
const res5 = shallowRef('' as Ref<string[]> | string | number) // ShallowRef<number> | Ref<string[]> | ShallowRef<string>

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	87 kB	33.1 kB	29.9 kB
vue.global.prod.js	133 kB	50 kB	44.8 kB

Usages

Name	Size	Gzip	Brotli
createApp	48.4 kB	19 kB	17.4 kB
createSSRApp	51.6 kB	20.3 kB	18.5 kB
defineCustomElement	50.7 kB	19.8 kB	18.1 kB
overall	61.7 kB	23.9 kB	21.8 kB

[codspeed-hq]

CodSpeed Performance Report

Merging #9839 will degrade performances by 42.4%

_{Comparing Alfred-Skyblue:fix/types/shallowRef (09d913b) with main (0a387df)}

Summary

❌ 1 regressions
✅ 52 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	Alfred-Skyblue:fix/types/shallowRef	Change
❌	write reactive obj, read 1000 computeds	39.5 ms	68.6 ms	-42.4%

[yyx990803]

This change does break the MaybeRef<T> case, but the correctness improvement is worth the tradeoff IMO.