JSDoc for overloads and implementation is not displayed

[tats-u]

Steps to reproduce

let state: number = 0;

/**
 * Sets the state to a new value.
 * @param value - A number to set the state directly.
 * @param newState - A function that takes the previous state and returns a new state.
 */
export function setState(value: number): void;
export function setState(newState: (prevState: number) => number): void;
export function setState(valueOrFunction: number | ((prevState: number) => number)): void {
  state = typeof valueOrFunction === 'function'
    ? valueOrFunction(state)
    : valueOrFunction;
}

/**
 * Gets the current state value.
 * @returns The current state as a number.
 */
export function getState(): number {
  return state;
}

I found this regression in parseFormData in @remix-run/form-data-parser.

https://github.com/remix-run/remix/blob/e8a0bff7aca39363ce53ba4deee7310cdd0e9016/packages/form-data-parser/src/lib/form-data.ts#L74-L102

バージョン: 1.108.2 (user setup)
コミット: c9d77990917f3102ada88be140d28b038d1dd7c7
日付: 2026-01-21T13:52:09.270Z
Electron: 39.2.7
ElectronBuildId: 12953945
Chromium: 142.0.7444.235
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Windows_NT x64 10.0.26200

1. Launch VS Code
2. Install the TS Native Preview Extension (0.20260127.1)
3. Create a new file
4. Paste the above code
5. Hover the mouse pointer over the function signatures other than function setState(value: number): void
6. "TypeScript Native Preview: Enable (Experimental)/Disable" and go to 5. again

Behavior with typescript@5.9

Non-top overload setState(newState: (prevState: number) => number): void:

Implementation setState(valueOrFunction: number | ((prevState: number) => number)): void:

Behavior with tsgo

"(+1 overload)" and the JSDoc are not displayed in other than the top overload signature.

Non-top overload setState(newState: (prevState: number) => number): void:

Implementation setState(valueOrFunction: number | ((prevState: number) => number)): void:

[ahejlsberg]

The changes are actually intentional. Strada always displays an overload count, whereas Corsa limits it to cases where the overload information actually comes into play. For example:

type A = { a: string }
type B = { b: string }
type C = { c: string }
type D = { d: string }
type E = { e: string }

function foo(x: A): A;
function foo(x: B): B;
function foo(x: C): C;
function foo(x: D): D;
function foo(x: E): E;
function foo(x: A | B | C | D | E): A | B | C | D | E {
    return x
}

foo  // Hover shows all overloads
foo({ d: "d"})  // Hover shows specific overload

Above, in Corsa, hovering over a specific overload declaration shows only that overload, and hovering over the implementation signature shows only the implementation signature. No overload counts are displayed since it is clear which signature is of interest. (Strada is weird here because it displays the first overload when hovering over the implementation signature.)

However, hovering over a general reference shows all overloads (or rather, up to four and then three plus an indicator of how many more exist):

whereas hovering over a call shows only the specific overload for that call:

[tats-u]

I see, but the disappearance of JSDoc matters much more. Can Corsa inherit the JSDoc for the top overload declaration like Strada (include 6)?

[ahejlsberg]

Can Corsa inherit the JSDoc for the top overload declaration like Strada

Yes, that seeems like something we want to do.