It is very hard to determine in advance whether class linking will
fail due to missing dependencies in variance checks (#7314 attempts
this). This patch takes an alternative approach where we try to
perform inheritance on a copy of the class (zend_lazy_class_load)
and then restore the original class if inheritance fails. The fatal
error in that case is recorded and thrown as a warning later.
Closes GH-7319.
Nikita Popov
d836046ab8