FR: a way to have the return type of yield inferred from the yielded type #4245
Description
Feature request
I thought it would be nice to be able to implement an await-like pattern using generic Promises and generators.
Sadly, I don't seem to be able to make PHPStan understand that the result of yield is dependent on the type of promise yielded.
Is this something that would be good for PHPStan itself, or is there a way that this could be implemented by an extension?