Inconsistency when assigning a never type parameter to any[] type parameter

[sw6ueyz]

🔎 Search Terms

inconsistency any never parameter

🕗 Version & Regression Information

• This changed between versions 4.9.5 and 5.0.4

⏯ Playground Link

https://www.typescriptlang.org/play?ts=5.0.4#code/FDAuE8AcFMAIBUCMsC8sAUHYA9YC5YA7aAN2gCdYBKVAPlhIHsBLAE1g+tmm1GkNYBnLJgB04nPlgBDQuADaAXS4p6TNpy4B+WKHIBXOAQBm0gDaDoAbhAQYCAEyoRkgsTKUaq2PsIBrQkYAd0IuHj4BYUwxCVwCWQVlL3pfAODQmh09QylTC2sQAHpChGRmYTzLABpHWHLdA2hgIA

💻 Code

type T1 = ( ( x : never ) => void    ) extends ( ( ... x : any[] ) => void    ) ? true : false;

type T2 = ( ( x : never ) => unknown ) extends ( ( ... x : any[] ) => unknown ) ? true : false;

// T1 is false, T2 is true

🙁 Actual behavior

5.0.4 and after : T1 is false, T2 is true.
4.9.5 and before : T1 is false, T2 is false.

🙂 Expected behavior

At least T1 and T2 should be the same value.
And if any is not assignable to never, both should be false.

Additional information about the issue

5.0.4 link:

https://www.typescriptlang.org/play?ts=5.0.4#code/FDAuE8AcFMAIBUCMsC8sAUHYA9YC5YA7aAN2gCdYBKVAPlhIHsBLAE1g+tmm1GkNYBnLJgB04nPlgBDQuADaAXS4p6TNpy4B+WKHIBXOAQBm0gDaDoAbhAQYCAEyoRkgsTKUaq2PsIBrQkYAd0IuHj4BYUwxCVwCWQVlL3pfAODQmh09QylTC2sQAHpChGRmYTzLABpHWHLdA2hgIA

4.9.5 link:

https://www.typescriptlang.org/play?ts=4.9.5#code/FDAuE8AcFMAIBUCMsC8sAUHYA9YC5YA7aAN2gCdYBKVAPlhIHsBLAE1g+tmm1GkNYBnLJgB04nPlgBDQuADaAXS4p6TNpy4B+WKHIBXOAQBm0gDaDoAbhAQYCAEyoRkgsTKUaq2PsIBrQkYAd0IuHj4BYUwxCVwCWQVlL3pfAODQmh09QylTC2sQAHpChGRmYTzLABpHWHLYSuhgIA

[RyanCavanaugh]

This changed on purpose in #52282

[typescript-bot]

This issue has been marked as "Working as Intended" and has seen no recent activity. It has been automatically closed for house-keeping purposes.