Coming from https://github.com/ramsey/uuid/pull/603, this is an attempt
to fix the errors raised by the current phpstan settings.
I went through each of the errors raised by phpstan with the following
approach.
- If a method is part of an `@immutable` class, we can consider it pure,
assuming it only affects internal variables.
- If a potentially pure method is calling a class's method that is only
swapped during testing (and not during normal usage), then we can
consider the calling method pure.
- If a class is marked deprecated, don't bother with attempting to mark
it pure or immutable.
Ben Ramsey
Brandon Morrison
Ben Ramsey