Type inference in Array<T>.filter()

[LouisBoucquet]

Bug Report

🔎 Search Terms

Type inferance

🕗 Version & Regression Information

This bug occurs in version 4.5.2;

⏯ Playground Link

Playground link with relevant code

💻 Code

function tIsOfTypeP(t: T): t is P {
	// Logic
}

const array: T[] = [...];

// newArray is still of type T[]
const newArray = array
	.filter(t => tIsOfTypeP(t));

🙁 Actual behavior

The variable newArray is of type Array<T>.

🙂 Expected behavior

The variable newArray is of type Array<P>. You know that only elements will remain of type P.

[MartinJohns]

Duplicate of #20218. You're not passing a type guard function to filter.

[LouisBoucquet]

Shouldn't the type of the lambda become a typeguard?

[MartinJohns]

No. See #10734.

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.