`cb: (x: T) => void` not assignable to `cb: (x: T) => void` when it has an overload: "'any' is not assignable to 'never'"

TypeScript Version: 2.9.0-dev.20180411

Code

declare function provide<T>(cb: (x: T) => void): void;
declare function provide<T>(cb: (x: T[keyof T]) => void): void;

declare function provider<T>(provide: (cb: (x: T) => void) => void): void;
provider(provide);

Expected behavior:

No error.

Actual behavior:

src/a.ts(4,10): error TS2345: Argument of type '{ <T>(cb: (x: T) => void): void; <T>(cb: (x: T[keyof T]) => void): void; }' is not assignable to parameter of type '(cb: (x: never) => void) => void'.
  Types of parameters 'cb' and 'cb' are incompatible.
    Types of parameters 'x' and 'x' are incompatible.
      Type 'any' is not assignable to type 'never'.

Worked in typescript@2.9.0-dev.20180327, broken in typescript@2.9.0-dev.20180328.

Tried fixing this, but ran into another case where an overload breaks type inference:

declare function reverse(a: ReadonlyArray<number>): ReadonlyArray<number>;

declare function incrementEvery(list: ReadonlyArray<number>): ReadonlyArray<number>;
declare function incrementEvery(x: ReadonlySet<number>): ReadonlySet<number>;

declare function compose<T>(
    second: (x: ReadonlyArray<number>) => T,
    first: (x0: ReadonlyArray<number>) => ReadonlyArray<number>,
): (x0: ReadonlyArray<number>) => T;

const works = compose<ReadonlyArray<number>>(incrementEvery, reverse);
const broke: (nums: ReadonlyArray<number>) => ReadonlyArray<number> = compose(incrementEvery, reverse);

src/a.ts(12,79): error TS2345: Argument of type '{ (list: ReadonlyArray<number>): ReadonlyArray<number>; (x: ReadonlySet<number>): ReadonlySet<num...' is not assignable to parameter of type '(x: ReadonlyArray<number>) => ReadonlySet<number>'.
  Type 'ReadonlyArray<number>' is not assignable to type 'ReadonlySet<number>'.
    Property 'has' is missing in type 'ReadonlyArray<number>'.

Unlike the above issue, this was broken in all the way back in 2.0.

[weswigham]

I've opened a PR with a potential fix for the first, and opened a new issue for the second (since it seems to have a separate root cause) so this issue can just track the first.

[RyanCavanaugh]

The fix here seems to have nonzero perf impact and we haven't seen any other reports. Punting for now.