fix workaround

Author: jdconrad

modules/lang-painless/src/main/java/org/elasticsearch/painless/DefBootstrap.java

@@ -201,14 +201,10 @@ protected MethodHandle computeValue(Class<?> receiverType) {
                     try {
                         return lookup(flavor, name, receiverType).asType(type);
                     } catch (Throwable t) {
-                        // ClassValue.getFromHashMap wraps checked exceptions as Error, but
-                        // we do not want to crash here because we could not process the type
-                        // correctly as part of a script, so we instead unwrap the Error and
-                        // rethrow the original exception
-                        if (t instanceof Error && ((Error) t).getCause() instanceof Exception) {
-                            t = (Exception) ((Error) t).getCause();
-                        }
-                        Def.rethrow(t);
+                        // ClassValue.getFromHashMap wraps checked exceptions as Error, so we
+                        // use a sentinel class [PainlessWrapperError] here to work around
+                        // this issue and later unwrap the original exception
+                        Def.rethrow(new PainlessWrappedError(t));
                         throw new AssertionError();
                     }
                 }

modules/lang-painless/src/main/java/org/elasticsearch/painless/PainlessScript.java

@@ -46,6 +46,9 @@ public interface PainlessScript {
      * @return The generated ScriptException.
      */
     default ScriptException convertToScriptException(Throwable t, Map<String, List<String>> extraMetadata) {
+        if (t instanceof PainlessWrappedError) {
+            t = t.getCause();
+        }
         // create a script stack: this is just the script portion
         List<String> scriptStack = new ArrayList<>();
         ScriptException.Position pos = null;

modules/lang-painless/src/main/java/org/elasticsearch/painless/PainlessWrappedError.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.painless;
+
+/**
+ * Checked exceptions are wrapped in {@link ClassValue}#getFromHashMap in Error
+ * which leads to unexpected behavior in Painless. This class is used as a
+ * workaround for that exception wrapping.
+ */
+public class PainlessWrappedError extends Error {
+
+    /**
+     * Constructor.
+     * @param cause The {@link Throwable} cause.
+     */
+    public PainlessWrappedError(final Throwable cause) {
+        super(cause);
+    }
+}

modules/lang-painless/src/main/java/org/elasticsearch/painless/phase/PainlessUserTreeToIRTreePhase.java

@@ -12,6 +12,7 @@
 import org.elasticsearch.painless.Location;
 import org.elasticsearch.painless.PainlessError;
 import org.elasticsearch.painless.PainlessExplainError;
+import org.elasticsearch.painless.PainlessWrappedError;
 import org.elasticsearch.painless.ScriptClassInfo;
 import org.elasticsearch.painless.ScriptClassInfo.MethodArgument;
 import org.elasticsearch.painless.ir.BinaryImplNode;
@@ -415,6 +416,7 @@ protected static void injectSandboxExceptions(FunctionNode irFunctionNode) {
 
             for (Class<? extends Throwable> throwable : List.of(
                 PainlessError.class,
+                PainlessWrappedError.class,
                 LinkageError.class,
                 OutOfMemoryError.class,
                 StackOverflowError.class,

modules/lang-painless/src/test/java/org/elasticsearch/painless/DefBootstrapTests.java

@@ -139,9 +139,11 @@ public void testMegamorphic() throws Throwable {
         map.put("a", "b");
         assertEquals(2, (int) handle.invokeExact((Object) map));
 
-        final IllegalArgumentException iae = expectThrows(IllegalArgumentException.class, () -> {
+        final PainlessWrappedError pwe = expectThrows(PainlessWrappedError.class, () -> {
             Integer.toString((int) handle.invokeExact(new Object()));
         });
+        assertTrue(pwe.getCause() instanceof IllegalArgumentException);
+        IllegalArgumentException iae = (IllegalArgumentException) pwe.getCause();
         assertEquals("dynamic method [java.lang.Object, size/0] not found", iae.getMessage());
         assertTrue("Does not fail inside ClassValue.computeValue()", Arrays.stream(iae.getStackTrace()).anyMatch(e -> {
             return e.getMethodName().equals("computeValue") && e.getClassName().startsWith("org.elasticsearch.painless.DefBootstrap$PIC$");