Generic not inferred inside mapped type parameter

TypeScript Version: 3.2.2

Search Terms: generic inference {} createStructuredSelector mapped types

Code

type Selector<S, R> = (state: S) => R;

declare function createStructuredSelector<S, T>(
    selectors: { [K in keyof T]: Selector<S, T[K]> },
): Selector<S, T>;

type State = { foo: number };
declare const mySelector: Selector<State, boolean>;

// Workaround: use explicit generics
// const result = createStructuredSelector<State, { mySelector: boolean }>({

// `State` generic incorrectly inferred as `{}`.
const result = createStructuredSelector({
    // Unexpected type error under `strictFunctionTypes` due to bad inference (above)
    mySelector,
});

result;

Start by reproducing the TypeScript 3.2.2 example with the mapped type and strictFunctionTypes enabled, then trace the generic inference behavior for createStructuredSelector. Done means the unannotated call infers State instead of {} and no longer produces the reported type error; no source file or test path is named in the issue.