7.8.2 introduces breaking changes

[ilyakonrad]

Describe the bug

Calling .next() with no arguments like this

new Observable((observer) => {
  observer.next()
}

shows error

Expected 1 arguments, but got 0.ts(2554)

Subscriber.d.ts(42, 10): An argument for 'value' was not provided.

Expected behavior

No breaking changes in patch version updates.

Version

7.8.2

Additional context

Duplicate of #7534.

[hakimio]

I guess now you have to explicitly specify the generic type:

new Observable<void>((observer) => {
  observer.next()
}

Either the default generic should be set to void (class Observable<T = void>) for the Observable or this breaking change should be postponed until v8.

[dgadelha]

The changelog mentions this as part of the 7.8.2 patch release:

subscriber: strict type signature for next method (#7172) (0e2ef5e)

Whereas the PR explicitly has on the description:

BREAKING CHANGE: Subscriber.prototype.next now takes strict argument.

Yet, it was released in a patch version.

[hakimio]

@dgadelha
Breaking changes do not belong in patch releases. This should have been postponed for next major or the typing introduced in a non-breaking way like I mentioned above with a good default.

[dgadelha]

@hakimio I'm with you! I just pointed out that the author of the PR explicitly mentioned this was a breaking change, yet it was still released as a patch version. I’ve updated my comment to make that clearer :)

[samwightt]

Jumping in again, this is introducing type errors in our codebase where there were none previously. This is absolutely a breaking change and should've been included in a major version bump, along with guidance on how to remediate.

[SvetlaGeorgieva]

Yep, and the docs are incorrect at the moment, as they still mention usage of next() with no parameters, which is no longer allowed: https://rxjs.dev/guide/subject#void-subject

We also experienced the breaking changes in our project.