Overload is not recognized correctly in some cases

[mochiya98]

Bug Report

🔎 Search Terms

generics overload

🕗 Version & Regression Information

• 4.7.4(current), 4.8.0-beta(beta)

⏯ Playground Link

Playground link with relevant code

💻 Code

type A1<T> = { type: "a1", v: T };
type B1<T> = { type: "b1", v: T };
type A2 = { a2: string };
type B2 = { b2: string };

function fn<T>(p1: (pp1: 0) => A1<T>, p2: (pp2: A2) => 0): void;
function fn<T>(p1: (pp1: 0) => B1<T>, p2: (pp2: B2) => 0): void;
function fn<T>(
 p1:
 | ((pp1: 0) => A1<T>)
 | ((pp1: 0) => B1<T>),
 p2:
 | ((pp2: A2) => 0)
 | ((pp2: B2) => 0)
) {}

const valA1: A1<string> = ({ type: "a1", v: "" });
const valB1: B1<string> = ({ type: "b1", v: "" });

// expect A
fn((ap1) => valA1, (ap2) => 0);
fn((ap1) => valA1, (ap2: A2) => 0); 
fn((ap1) => valA1, (ap2: any) => 0);
fn((ap1) => valA1, (ap2: unknown) => 0);
fn((ap1: 0) => valA1, (ap2) => 0);
// expect B
fn((bp1) => valB1, (bp2) => 0); // but it will be A, only this will result in an error
fn((bp1) => valB1, (bp2: B2) => 0); 
fn((bp1) => valB1, (bp2: any) => 0);
fn((bp1) => valB1, (bp2: unknown) => 0);
fn((bp1: 0) => valB1, (bp2) => 0);

🙁 Actual behavior

No overload matches this call.
 Overload 1 of 2, '(p1: (pp1: 0) => A1<string>, p2: (pp2: A2) => 0): void', gave the following error.
 Type 'B1<string>' is not assignable to type 'A1<string>'.
 Types of property 'type' are incompatible.
 Type '"b1"' is not assignable to type '"a1"'.
 Overload 2 of 2, '(p1: (pp1: 0) => B1<string>, p2: (pp2: B2) => 0): void', gave the following error.
 Argument of type '(bp2: A2) => 0' is not assignable to parameter of type '(pp2: B2) => 0'.
 Types of parameters 'bp2' and 'pp2' are incompatible.
 Property 'a2' is missing in type 'B2' but required in type 'A2'.(2769)

🙂 Expected behavior

No errors

[RyanCavanaugh]

See #30134 - inference only does a fixed number of passes, which isn't an algorithm capable of resolving this.

[PabloLION]

Here's a shorter MRE to address/demonstrate the problem. I hope it can be helpful:

type Fruit = "apple" | "banana";

function printFruit(fruit: "apple");
function printFruit(fruit: "banana");
function printFruit(fruit: Fruit) {
 console.log(fruit);
}

function callPrintFruit(fruit: Fruit) {
 printFruit(fruit); // Error here: No overload matches this call.
}

Playground: https://www.typescriptlang.org/play?ts=4.7.4#code/C4TwDgpgBAYgTgVwJbCgXigIgIZjAGwkygB8sAjbAO2u0wG4AoRgMwSoGNgkB7KqMHCRVg8ZMAAULRCgBcWXASIBKJm07c+AoSLEopM4PMyUaNTKtbsuvfoOGjDB8fL3BlUAN6MoUDnwBnHkIAOnweAHNnFEsAX2Z1Gy0ObHx8AAUdR3Foo1hDD29fe10naXFVKAB6KqgAUTg4HjgoAAsIOAh5ADkeKB4ANw7w7AATKABbbGAOdoCoYFakeZS0kMZ4oA

[Septh]

I was about to file a similar issue but found this one. To build on Pablo LION (@PabloLION)'s comment, the following variation compiles OK (playground), which seems strange to me because the error is on the function call, not the function's body:

type Fruit = "apple" | "banana";

declare function printFruit(fruit: "apple"): void;
declare function printFruit(fruit: "banana"): void;
declare function printFruit(fruit: Fruit): void;

function callPrintFruit(fruit: Fruit) {
 printFruit(fruit); // No error here!
}