8303922: build-test-lib target is broken

Reviewed-by: erikj, jwaters

make/test/BuildTestLib.gmk

@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2015, 2020, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2015, 2023, 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
@@ -36,10 +36,11 @@ TEST_LIB_SUPPORT := $(SUPPORT_OUTPUTDIR)/test/lib
 
 $(eval $(call SetupJavaCompilation, BUILD_WB_JAR, \
     TARGET_RELEASE := $(TARGET_RELEASE_NEWJDK_UPGRADED), \
-    SRC := $(TEST_LIB_SOURCE_DIR)/sun $(TEST_LIB_SOURCE_DIR)/jdk/test/whitebox/parser, \
+    SRC := $(TEST_LIB_SOURCE_DIR)/jdk/test/whitebox/parser, \
     BIN := $(TEST_LIB_SUPPORT)/wb_classes, \
     JAR := $(TEST_LIB_SUPPORT)/wb.jar, \
-    DISABLED_WARNINGS := deprecation removal, \
+    DISABLED_WARNINGS := deprecation removal preview, \
+    JAVAC_FLAGS := --enable-preview, \
 ))
 
 TARGETS += $(BUILD_WB_JAR)
@@ -51,7 +52,8 @@ $(eval $(call SetupJavaCompilation, BUILD_TEST_LIB_JAR, \
     BIN := $(TEST_LIB_SUPPORT)/test-lib_classes, \
     HEADERS := $(TEST_LIB_SUPPORT)/test-lib_headers, \
     JAR := $(TEST_LIB_SUPPORT)/test-lib.jar, \
-    DISABLED_WARNINGS := try deprecation rawtypes unchecked serial cast removal, \
+    DISABLED_WARNINGS := try deprecation rawtypes unchecked serial cast removal preview, \
+    JAVAC_FLAGS := --enable-preview, \
 ))
 
 TARGETS += $(BUILD_TEST_LIB_JAR)

test/lib/jdk/test/lib/hexdump/ASN1Formatter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2023, 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
@@ -303,7 +303,7 @@ private int annotate(DataInputStream in, Appendable out, int available, String p
                 case TAG_BitString:
                     out.append(String.format("%s [%d]", tagName(tag), len));
                     do {
-                        var skipped = in.skip(len);
+                        var skipped = (int) in.skip(len);
                         len -= skipped;
                         available -= skipped;
                     } while (len > 0);