type NoInfer<T> = [T][T extends any ? 0 : never];
This type is used to block the compiler from using an inference site.
For example, given the following function inference:
declare function inference<T>(a: T, b: T);
inference("", 0);
// ~ Argument of type 'number' is not assignable to parameter of type 'string'.
T is inferred as string, because of the first argument.
If you want T to be inferred from the second parameter instead, you would have to block the compiler’s inference in the parameter a.
This is where NoInfer can be used:
declare function inference<T>(a: NoInfer<T>, b: T);
inference("", 0);
// ~~ Argument of type 'string' is not assignable to parameter of type 'number'.
Now, T is inferred as number, as the compiler could not use the first argument as a point of inference.
Since T is number, the first argument now generates an error saying that a string cannot be assigned to a number.