Bug with conditional types and constraints

[SimonMeskens]

type Weird = (<U extends boolean>(a: U) => never) extends 
    (<U extends true>(a: U) => never) ? never : never;

This type puts the type checker in some sort of weird state where it's never narrowed into anything useful. I assume the proper type should be boolean never.

[jcalz]

the proper type should be boolean

boolean? Or never?

[SimonMeskens]

Sorry, yes, never, I changed the code slightly just before posting to try and demonstrate the bug better. I'll adjust the OP.

type Weird = (<U extends boolean>(a: U) => U) extends 
    (<U extends true>(a: U) => infer T) ? T : never;

This was the original code, in which case the answer is boolean, but it confuses the issue, because the problem is due to the contraints, not due to anything to do with return types or infer.