Use AbstractImageHeapList to restrict SubstrateDiagnostics.thunks runtime type.

Author: cstancu

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/SubstrateDiagnostics.java

@@ -28,7 +28,6 @@
 import static com.oracle.svm.core.option.RuntimeOptionKey.RuntimeOptionKeyFlag.RelevantForCompilationIsolates;
 
 import java.util.Arrays;
-import java.util.List;
 
 import org.graalvm.collections.EconomicMap;
 import org.graalvm.nativeimage.CurrentIsolate;
@@ -101,9 +100,9 @@
 import com.oracle.svm.core.traits.SingletonLayeredInstallationKind.Independent;
 import com.oracle.svm.core.traits.SingletonLayeredInstallationKind.InitialLayerOnly;
 import com.oracle.svm.core.traits.SingletonTraits;
+import com.oracle.svm.core.util.AbstractImageHeapList;
 import com.oracle.svm.core.util.CounterSupport;
 import com.oracle.svm.core.util.ImageHeapList;
-import com.oracle.svm.core.util.RuntimeImageHeapList;
 import com.oracle.svm.core.util.TimeUtils;
 import com.oracle.svm.core.util.VMError;
 
@@ -1283,7 +1282,7 @@ public static class DiagnosticThunkRegistry {
         @Platforms(Platform.HOSTED_ONLY.class) //
         final int runtimeCompilationPosition;
 
-        private final List<DiagnosticThunk> thunks = ImageHeapList.create(DiagnosticThunk.class);
+        private final AbstractImageHeapList<DiagnosticThunk> thunks = ImageHeapList.create(DiagnosticThunk.class);
         private int[] initialInvocationCount;
 
         @Fold
@@ -1368,12 +1367,7 @@ int size() {
         }
 
         DiagnosticThunk getThunk(int index) {
-            /*
-             * Use an explicit cast to aid open-world analysis. Otherwise, this may trigger false
-             * positive violations of @RestrictHeapAccess since some implementations of List.get()
-             * can allocate.
-             */
-            return ((RuntimeImageHeapList<DiagnosticThunk>) thunks).get(index);
+            return thunks.get(index);
         }
 
         int getInitialInvocationCount(int index) {

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/util/AbstractImageHeapList.java

@@ -0,0 +1,46 @@
+/*
+ * 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.core.util;
+
+import java.util.AbstractList;
+import java.util.ArrayList;
+import java.util.List;
+
+import com.oracle.svm.core.heap.RestrictHeapAccess;
+import com.oracle.svm.core.util.ImageHeapList.HostedImageHeapList;
+
+/**
+ * Super type for {@link HostedImageHeapList} and {@link RuntimeImageHeapList} that allows declaring
+ * a more restricted type for fields initialized with {@link ImageHeapList#create(Class)} to aid
+ * open-world analysis. When such a field is analysed in an open-world it gets injected all possible
+ * subtypes of its declared type. Declaring the type as {@link AbstractImageHeapList} allows us to
+ * only inject {@link RuntimeImageHeapList}.This enables a more precise analysis and avoids for
+ * example triggering false-positive violations of @{@link RestrictHeapAccess}: if the field was
+ * declared as {@link List} then implementations of {@link List} for which simple access operations
+ * can allocate, such as {@link ArrayList#get(int)}, could become reachable from code annotated
+ * with @{@link RestrictHeapAccess}.
+ */
+public abstract sealed class AbstractImageHeapList<E> extends AbstractList<E> permits HostedImageHeapList, RuntimeImageHeapList {
+}

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/util/ImageHeapList.java

@@ -25,7 +25,6 @@
 package com.oracle.svm.core.util;
 
 import java.lang.reflect.Array;
-import java.util.AbstractList;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
@@ -57,17 +56,17 @@
 public final class ImageHeapList {
 
     @Platforms(Platform.HOSTED_ONLY.class) //
-    public static <E> List<E> create(Class<E> elementClass) {
+    public static <E> AbstractImageHeapList<E> create(Class<E> elementClass) {
         return create(elementClass, null);
     }
 
     @Platforms(Platform.HOSTED_ONLY.class) //
-    public static List<?> createGeneric(Class<?> elementClass) {
+    public static AbstractImageHeapList<?> createGeneric(Class<?> elementClass) {
         return create(elementClass, null);
     }
 
     @Platforms(Platform.HOSTED_ONLY.class) //
-    public static <E> List<E> create(Class<E> elementClass, Comparator<E> comparator) {
+    public static <E> AbstractImageHeapList<E> create(Class<E> elementClass, Comparator<E> comparator) {
         VMError.guarantee(!BuildPhaseProvider.isAnalysisFinished(), "Trying to create an ImageHeapList after analysis.");
         return new HostedImageHeapList<>(elementClass, comparator);
     }
@@ -76,7 +75,7 @@ private ImageHeapList() {
     }
 
     @Platforms(Platform.HOSTED_ONLY.class) //
-    public static final class HostedImageHeapList<E> extends AbstractList<E> {
+    public static final class HostedImageHeapList<E> extends AbstractImageHeapList<E> {
         private final Comparator<E> comparator;
         private final List<E> hostedList;
         private final RuntimeImageHeapList<E> runtimeList;

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/util/RuntimeImageHeapList.java

@@ -24,8 +24,6 @@
  */
 package com.oracle.svm.core.util;
 
-import java.util.AbstractList;
-
 import org.graalvm.nativeimage.Platform;
 import org.graalvm.nativeimage.Platforms;
 
@@ -34,7 +32,7 @@
 /**
  * The immutable runtime list view for an {@link ImageHeapList}.
  */
-public final class RuntimeImageHeapList<E> extends AbstractList<E> {
+public final class RuntimeImageHeapList<E> extends AbstractImageHeapList<E> {
 
     E[] elementData;