Fix regression for optional JSDoc types which throws TS2463 in typescript@next

[voxpelli]

Bug Report

🔎 Search Terms

optional jsdoc regression

🕗 Version & Regression Information

This started occurring in nightly after #50094 was merged to fix #49869 and still happens (see these cron job type checks in pony-cause which retests against nightly three times a week).

This does not happen in 4.8 beta

• This changed between versions 4.8-beta and nightly

⏯ Playground Link

Since the Playground is for TS code, not JS code, here's a link to a piece of code: https://github.com/voxpelli/pony-cause/blob/4009048a41d772cb29673f1c45cc55e9717e523f/lib/error-with-cause.js#L5-L9

And more in this thread: voxpelli/pony-cause#45

💻 Code

   /** 
    * @param {{ cause?: string }} [options] 
    */ 
   function foo ({ cause } = {}) { 

🙁 Actual behavior

Explicitly specifying the options as optional ([options] ) causes this error as it is already implicitly marked as optional by having been set a default value ({ cause } = {}):

error TS2463: A binding pattern parameter cannot be optional in an implementation signature.

🙂 Expected behavior

One of:

1. Preferably that TypeScript keep accepting arguments that's been explicitly marked as optional, even if that is redundant
2. At least change the error message to something that makes more sense in a JSDoc context than "A binding pattern parameter cannot be optional in an implementation signature."

See more in this thread: voxpelli/pony-cause#45 and in #50094 (comment), where @sandersn said that he is in favor the current new behavior.

[voxpelli]

Seems like this is actually affecting TS 4.8.2

[mohd-akram]

Any update on this?

[turadg]

Any update on this?

Here is a TS playground link showing it's still a problem in 4.9.0-dev.20220921 (Nightly). Also 4.8.2, and not 4.7.4.

However it now has an assignee and is part of the TypeScript 4.9.0 milestone so I think you can expect it to be fixed in a future nightly.