Add ReachabilityHandlerAssertFeature.

Author: cstancu

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/ReachabilityHandlerAssertFeature.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2025, 2025, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.svm.hosted;
+
+import org.graalvm.nativeimage.hosted.Feature;
+
+import com.oracle.svm.core.SubstrateUtil;
+import com.oracle.svm.core.feature.AutomaticallyRegisteredFeature;
+import com.oracle.svm.core.feature.InternalFeature;
+import com.oracle.svm.core.util.VMError;
+
+/**
+ * Ensure that a {@link org.graalvm.nativeimage.hosted.Feature.DuringAnalysisAccess} object is
+ * available when a reachability callback is executed for any of the reachable types.
+ */
+@AutomaticallyRegisteredFeature
+public class ReachabilityHandlerAssertFeature implements InternalFeature {
+    @Override
+    public boolean isInConfiguration(IsInConfigurationAccess access) {
+        return SubstrateUtil.assertionsEnabled();
+    }
+
+    @Override
+    public void beforeAnalysis(Feature.BeforeAnalysisAccess access) {
+        access.registerSubtypeReachabilityHandler(this::onTypeReachable, Object.class);
+    }
+
+    private void onTypeReachable(DuringAnalysisAccess access, Class<?> cls) {
+        VMError.guarantee(access != null, "DuringAnalysisAccess object is not available when processing class %s.", cls.getName());
+    }
+}