Ignore java.lang.Object methods (identified by method name plus method descriptor) when creating muzzle references.

mcculls · mcculls · commit d06958248a5a · 2025-10-02T11:54:44.000+01:00
This helps when compiling with Java 18+ because javac will now use INVOKEINTERFACE with the interface name to call java.lang.Object methods (so the 'owner' is now seen as the interface) whereas before it was using INVOKEVIRTUAL with java.lang.Object as the method 'owner'. the key change is described in https://bugs.openjdk.org/browse/JDK-8272715: "invocations of java.lang.Object methods on interfaces in the classfile will use invokeinterface referring to the interface, which is consistent with JLS 9.2. This will be done regardless of whether the interface declares the method explicitly or not."
diff --git a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/muzzle/ReferenceCreator.java b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/muzzle/ReferenceCreator.java
@@ -7,6 +7,7 @@
 import datadog.trace.bootstrap.Constants;
 import de.thetaphi.forbiddenapis.SuppressForbidden;
 import java.io.InputStream;
+import java.lang.reflect.Method;
 import java.util.ArrayDeque;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
@@ -39,6 +40,15 @@ public class ReferenceCreator extends ClassVisitor {
 
   private static final int UNDEFINED_LINE = -1;
 
+  /** Set containing name+descriptor signatures of Object methods. */
+  private static final Set<String> OBJECT_METHODS = new HashSet<>();
+
+  static {
+    for (Method m : Object.class.getMethods()) {
+      OBJECT_METHODS.add(methodSig(m.getName(), Type.getMethodDescriptor(m)));
+    }
+  }
+
   /**
    * Generate all references reachable from a given class.
    *
@@ -323,7 +333,7 @@ public void visitMethodInsn(
         final String name,
         final String descriptor,
         final boolean isInterface) {
-      if (ignoreReference(owner)) {
+      if (ignoreReference(owner) || ignoreObjectMethod(name, descriptor)) {
         return;
       }
 
@@ -490,4 +500,12 @@ private static boolean ignoreReference(String name) {
     }
     return false;
   }
+
+  private static boolean ignoreObjectMethod(String methodName, String methodDescriptor) {
+    return OBJECT_METHODS.contains(methodSig(methodName, methodDescriptor));
+  }
+
+  private static String methodSig(String methodName, String methodDescriptor) {
+    return methodName + methodDescriptor;
+  }
 }
