setInput() triggers ngOnChanges and mark component when it should not

Which @angular/* package(s) are the source of the bug?

core

Is this a regression?

No

Description

I thought ComponentRef.setInput() will:

• set input
• mark component when neccessary
• make sure ngOnChanges is called when neccessary

However it is called when OnPush component is used and input doesn’t change so i think it is not correct behavior.

https://user-images.githubusercontent.com/10418323/190913482-70c5da4c-1855-479f-a744-20fae0afff8e.mp4

Please provide a link to a minimal reproduction of the bug

https://stackblitz.com/edit/angular-ivy-yo1znz?file=src/app/hello.component.ts

Please provide the exception or error you saw

No response

Please provide the environment you discovered this bug in (run ng version)

No response

Anything else?

Of course we can check it manually, but only “component.instance” is available for the developers from “PUBLIC API” - and that’s problem in case of setters without getters etc.

[pkozlowski-opensource]

ngOnChanges doesn’t do prev / current comparison, this happens before input values are updated (and hence it is not implemented in the current version of the API). So it is not a question of the public API availability. Currently you would have to remember prev values and do the comparison on your side. As I’ve mentioned, this is sth we might consider doing inside setInput, although it is not clear what the design should be and if this is the right direction at all…

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