swc/crates/swc_ecma_parser/tests/tsc/intraExpressionInferences.ts

// @strict: true
// @declaration: true

// Repros from #47599

declare function callIt<T>(obj: {
    produce: (n: number) => T,
    consume: (x: T) => void
}): void;

callIt({
    produce: () => 0,
    consume: n => n.toFixed()
});

callIt({
    produce: _a => 0,
    consume: n => n.toFixed(),
});

callIt({
    produce() {
        return 0;
    },
    consume: n => n.toFixed()
});

declare function callItT<T>(obj: [(n: number) => T, (x: T) => void]): void;

callItT([() => 0, n => n.toFixed()]);
callItT([_a => 0, n => n.toFixed()]);

// Repro from #25092

interface MyInterface<T> {
    retrieveGeneric: (parameter: string) => T,
    operateWithGeneric: (generic: T) => string
}

const inferTypeFn = <T>(generic: MyInterface<T>) => generic;

const myGeneric = inferTypeFn({
    retrieveGeneric: parameter => 5,
    operateWithGeneric: generic => generic.toFixed()
});

// Repro #38623

function make<M>(o: { mutations: M,  action: (m: M) => void }) { }

make({
   mutations: {
       foo() { }
   },
   action: (a) => { a.foo() }
});

// Repro from #38845

declare function foo<A>(options: { a: A, b: (a: A) => void }): void;

foo({
    a: () => { return 42 },
    b(a) {},
});

foo({
    a: function () { return 42 },
    b(a) {},
});

foo({
    a() { return 42 },
    b(a) {},
});

// Repro from #38872

type Chain<R1, R2> = {
    a(): R1,
    b(a: R1): R2;
    c(b: R2): void;
};

function test<R1, R2>(foo: Chain<R1, R2>) {}

test({
    a: () => 0,
    b: (a) => 'a',
    c: (b) => {
        const x: string = b;
    }
});

test({
    a: () => 0,
    b: (a) => a,
    c: (b) => {
        const x: number = b;
    }
});

// Repro from #41712

class Wrapper<T = any> {
    public value?: T;
}

type WrappedMap = Record<string, Wrapper>;
type Unwrap<D extends WrappedMap> = {
    [K in keyof D]: D[K] extends Wrapper<infer T> ? T : never;
};

type MappingComponent<I extends WrappedMap, O extends WrappedMap> = {
    setup(): { inputs: I; outputs: O };
    map?: (inputs: Unwrap<I>) => Unwrap<O>;
};

declare function createMappingComponent<I extends WrappedMap, O extends WrappedMap>(def: MappingComponent<I, O>): void;

createMappingComponent({
    setup() {
        return {
            inputs: {
                num: new Wrapper<number>(),
                str: new Wrapper<string>()
            },
            outputs: {
                bool: new Wrapper<boolean>(),
                str: new Wrapper<string>()
            }
        };
    },
    map(inputs) {
        return {
            bool: inputs.nonexistent,
            str: inputs.num,  // Causes error
        }
    }
});

// Repro from #48279

function simplified<T>(props: { generator: () => T, receiver: (t: T) => any }) {}

function whatIWant<T>(props: { generator: (bob: any) => T, receiver: (t: T) => any }) {}

function nonObject<T>(generator: (bob: any) => T, receiver: (t: T) => any) {}

simplified({ generator: () => 123, receiver: (t) => console.log(t + 2) })
whatIWant({ generator: (bob) => bob ? 1 : 2, receiver: (t) => console.log(t + 2) })
nonObject((bob) => bob ? 1 : 2, (t) => console.log(t + 2))

// Repro from #48466

interface Opts<TParams, TDone, TMapped> {
    fetch: (params: TParams, foo: number) => TDone,
    map: (data: TDone) => TMapped
}

function example<TParams, TDone, TMapped>(options: Opts<TParams, TDone, TMapped>) {
    return (params: TParams) => {
        const data = options.fetch(params, 123)
        return options.map(data)
    }
}

interface Params {
    one: number
    two: string
}

example({
    fetch: (params: Params) => 123,
    map: (number) => String(number)
});

example({
    fetch: (params: Params, foo: number) => 123,
    map: (number) => String(number)
});

example({
    fetch: (params: Params, foo) => 123,
    map: (number) => String(number)
});

// Repro from #45255

declare const branch:
  <T, U extends T>(_: { test: T, if: (t: T) => t is U, then: (u: U) => void }) => void

declare const x: "a" | "b"

branch({
  test: x,
  if: (t): t is "a" => t === "a",
  then: u => {
    let test1: "a" = u
  }
})