TSDocTypeScript will unify type parameters when comparing two generic functions.
ts
// @errors: 2322
type A = <T, U>(x: T, y: U) => [T, U];
type B = <S>(x: S, y: S) => [S, S];
function f(a: A, b: B) {
b = a; // Ok
a = b; // Error
}// @errors: 2322
type A = <T, U>(x: T, y: U) => [T, U];
type B = <S>(x: S, y: S) => [S, S];
function f(a: A, b: B) {
b = a; // Ok
a = b; // Error
}This flag can be used to remove that check.