8298162: Test PrintClasses hits assert when run with code that retransform classes

Reviewed-by: dholmes, mgronlun

Author: coleenp

src/hotspot/share/runtime/fieldDescriptor.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -102,7 +102,9 @@ void fieldDescriptor::reinitialize(InstanceKlass* ik, int index) {
   if (_cp.is_null() || field_holder() != ik) {
     _cp = constantPoolHandle(Thread::current(), ik->constants());
     // _cp should now reference ik's constant pool; i.e., ik is now field_holder.
-    assert(field_holder() == ik, "must be already initialized to this class");
+    // If the class is a scratch class, the constant pool points to the original class,
+    // but that's ok because of constant pool merging.
+    assert(field_holder() == ik || ik->is_scratch_class(), "must be already initialized to this class");
   }
   FieldInfo* f = ik->field(index);
   _access_flags = accessFlags_from(f->access_flags());

test/hotspot/jtreg/runtime/CommandLine/PrintClasses.java

@@ -30,6 +30,15 @@
  * @run main/othervm PrintClasses
  */
 
+/*
+ * @test
+ * @bug 8298162
+ * @summary Test jcmd VM.classes with JFR
+ * @requires vm.hasJFR
+ * @library /test/lib
+ * @run main/othervm -XX:StartFlightRecording PrintClasses
+ */
+
 import jdk.test.lib.process.OutputAnalyzer;
 import jdk.test.lib.JDKToolFinder;