[5.7.15] Breaking change for non int ids that are generated in the database

[zecipriano]

Since 5.7.15 (pull request #26622) the id of models, in some situations, is casted to int based only on the $incrementing value, disregarding $keyType.

This causes issues when the model has $keyType = 'string' and $incrementing = true.

In my case, I want to leave $incrementing as true because the id is being generated in the database as a default value (with the function gen_random_uuid()) but I still want Laravel to set the model id after inserting.

Granted, the meaning of 'incrementing' is being subverted to more of a 'being generated in the database', but, as far as I know, there is no other way to instruct Laravel to get the id of the inserted row and update the model with it.

[driesvints]

@staudenmeir any idea how we could tackle this?