http://hg.openjdk.java.net/amber/amber/, branch `sealed-types`
changeset:   60873:2a52a2f72a4e

Say, the following call

    int.class.isSealed();
or
    char.class.getPermittedSubtypes();

after successful compilation leads to (MacOS) :

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x000000010f7d1e23, pid=94154, tid=9987
#
# JRE version: OpenJDK Runtime Environment (15.0) (build 15-internal+0-adhoc.username.amber)
# Java VM: OpenJDK 64-Bit Server VM (15-internal+0-adhoc.username.amber, mixed mode, sharing, tiered, compressed oops, g1 gc, bsd-amd64)
# Problematic frame:
# V  [libjvm.dylib+0x3d1e23]  JVM_GetPermittedSubtypes+0xc4
#
# No core dump will be written. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#