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Rest element type not recognized for inner array types #45448
Description
Bug Report
Hello,
The compiler doesn't recognize an inner array type as an "array type" when inferred in a conditional type.
🔎 Search Terms
I searched for array, rest element, inner array type, multidimensional array type.
Couldn't find anything.
⏯ Playground Link
Playground link with relevant code
💻 Code
The compiler complains with the following code:
type PushToTopArray<T, ArrayOfArray extends any[][]> =
ArrayOfArray extends [infer TopArray, ...infer Rest] ?
[[T, ...TopArray], ...Rest] :
never;🙁 Actual behavior
with error: A rest element type must be an array type. (2574) on ...TopArray.
🙂 Expected behavior
But since ArrayOfArray extends any[][], the inferred TopArray should be of type any[] and therefore satisfy the rest element type.
Activity
RyanCavanaugh commentedon Aug 13, 2021
As a workaround, you can add this intersection:
miguel-leon commentedon Aug 13, 2021
Thanks!
I was using
Is it the same, or one way is better/more proper?
Edit: I think the intersection doesn't work quite as intended..
RyanCavanaugh commentedon Aug 13, 2021
Probably yours is better if the intersection doesn't work 😅. I wasn't sure what the intended behavior of the alias was.