useEffect didn't run in some rare case (lazy + memo)

[guoyunhe]

• Check if updating to the latest Preact version resolves the issue

Describe the bug

I have a simple app with the following structure:

• App (suspense)
  • Foobar (lazy)
    • Foo (memo)
    • Bar (lazy)

I found that in this case, Foo's useEffect() will NOT be executed. (But it does in React 18)

To Reproduce

https://codesandbox.io/p/sandbox/preact-memo-gpmrxk

Expected behavior

Show foobar

Actual behavior

Show bar

[JoviDeCroock]

This shortcoming originates from the detaching logic, located here currently it bubbles up in a straight line but it should reset every child up until the Suspense boundary, including siblings.

Edit: wait it does, but somehow the memo'd component just bails... we might need to set _force to true - I guess a similar fix would be needed for #3449 either way

[CaptainWang98]

I noticed the bug disappears if replace the memo(Foo) with Foo;
I spend several days but get no idea, can I get some clue here?

[JoviDeCroock]

As outlined in my comment it's a bug with memoization and can be addressed in the detaching logic by i.e. setting _force to true.