Bug report

As mentioned in the issue title.
PHPStan does not consider a class instance to be Stringable if the __toString() method is implemented in a trait that the class uses.
The condition $object instanceof \Stringable passes without any problems, but PHPStan reports:

Instanceof between XXX and Stringable will always evaluate to false.

Code snippet that reproduces the problem

https://phpstan.org/r/6621497c-dab7-4f5b-acfe-be260fac6546

Expected output

The object should be considered as Stringable.

Did PHPStan help you today? Did it make you happy in any way?

Ofc! currently it helps me detect errors during refactoring.