Painless: Fix errors allowing void to be assigned to def. (#27460)

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/EAssignment.java

@@ -20,7 +20,6 @@
 package org.elasticsearch.painless.node;
 
 import org.elasticsearch.painless.DefBootstrap;
-import org.elasticsearch.painless.Definition;
 import org.elasticsearch.painless.Definition.Cast;
 import org.elasticsearch.painless.Definition.Type;
 import org.elasticsearch.painless.Globals;
@@ -213,6 +212,11 @@ public final class EAssignment extends AExpression {
         // If the lhs node is a def optimized node we update the actual type to remove the need for a cast.
         if (lhs.isDefOptimized()) {
             rhs.analyze(locals);
+
+            if (rhs.actual.clazz == void.class) {
+                throw createError(new IllegalArgumentException("Right-hand side cannot be a [void] type for assignment."));
+            }
+
             rhs.expected = rhs.actual;
             lhs.updateActual(rhs.actual);
         // Otherwise, we must adapt the rhs type to the lhs type with a cast.

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/PSubDefCall.java

@@ -19,9 +19,7 @@
 
 package org.elasticsearch.painless.node;
 
-import java.util.Collections;
 import org.elasticsearch.painless.DefBootstrap;
-import org.elasticsearch.painless.Definition;
 import org.elasticsearch.painless.Globals;
 import org.elasticsearch.painless.Locals;
 import org.elasticsearch.painless.Location;
@@ -29,6 +27,7 @@ import org.elasticsearch.painless.MethodWriter;
 import org.objectweb.asm.Type;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.Set;
@@ -76,6 +75,10 @@ final class PSubDefCall extends AExpression {
                 totalCaptures += lambda.getCaptureCount();
             }
 
+            if (expression.actual.clazz == void.class) {
+                throw createError(new IllegalArgumentException("Argument(s) cannot be of [void] type when calling method [" + name + "]."));
+            }
+
             expression.expected = expression.actual;
             arguments.set(argument, expression.cast(locals));
         }

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/PSubDefField.java

@@ -20,7 +20,6 @@
 package org.elasticsearch.painless.node;
 
 import org.elasticsearch.painless.DefBootstrap;
-import org.elasticsearch.painless.Definition;
 import org.elasticsearch.painless.Definition.Type;
 import org.elasticsearch.painless.Globals;
 import org.elasticsearch.painless.Locals;

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

@@ -318,4 +318,13 @@ public class CastTests extends ScriptTestCase {
             exec("def x = 5L; boolean y = (boolean) (x + x); return y");
         });
     }
+
+    public void testIllegalVoidCasts() {
+        expectScriptThrows(IllegalArgumentException.class, () -> {
+            exec("def map = ['a': 1,'b': 2,'c': 3]; map.c = Collections.sort(new ArrayList(map.keySet()));");
+        });
+        expectScriptThrows(IllegalArgumentException.class, () -> {
+            exec("Map map = ['a': 1,'b': 2,'c': 3]; def x = new HashMap(); x.put(1, map.clear());");
+        });
+    }
 }