Index: src/main/org/codehaus/groovy/classgen/AsmClassGenerator.java
===================================================================
--- src/main/org/codehaus/groovy/classgen/AsmClassGenerator.java	(revision 18661)
+++ src/main/org/codehaus/groovy/classgen/AsmClassGenerator.java	(working copy)
@@ -518,15 +518,15 @@
 
     /**
      * method to determine if a method is a MOP method. This is done by the
-     * method name. If the name starts with "this$" or "super$", then it is
-     * a MOP method
+     * method name. If the name starts with "this$" or "super$" but does not 
+     * contain "$dist$", then it is an MOP method
      *
      * @param methodName name of the method to test
      * @return true if the method is a MOP method
      */
     public static boolean isMopMethod(String methodName) {
-        return methodName.startsWith("this$") ||
-                methodName.startsWith("super$");
+        return (methodName.startsWith("this$") ||
+                methodName.startsWith("super$")) && !methodName.contains("$dist$");
     }
 
     protected void visitConstructorOrMethod(MethodNode node, boolean isConstructor) {
Index: src/main/org/codehaus/groovy/classgen/Verifier.java
===================================================================
--- src/main/org/codehaus/groovy/classgen/Verifier.java	(revision 18654)
+++ src/main/org/codehaus/groovy/classgen/Verifier.java	(working copy)
@@ -438,6 +438,11 @@
     }
 
     public void visitMethod(MethodNode node) {
+    	//GROOVY-3712 - if it's an MOP method, it's an error as they aren't supposed to exist before ACG is invoked
+    	if(AsmClassGenerator.isMopMethod(node.getName())) {
+    		throw new RuntimeParserException("Found unexpected MOP methods in the class node for " + classNode.getName() +
+    				"(" + node.getName() + ")", classNode);
+    	}
         this.methodNode = node;
         adjustTypesIfStaticMainMethod(node);
         addReturnIfNeeded(node);
Index: src/main/org/codehaus/groovy/transform/DelegateASTTransformation.java
===================================================================
--- src/main/org/codehaus/groovy/transform/DelegateASTTransformation.java	(revision 18654)
+++ src/main/org/codehaus/groovy/transform/DelegateASTTransformation.java	(working copy)
@@ -125,7 +125,7 @@
     private void addDelegateMethod(FieldNode fieldNode, ClassNode owner, Map<String, MethodNode> ownMethods, Map.Entry<String, MethodNode> e, boolean deprecated) {
         MethodNode method = e.getValue();
 
-        if (!method.isPublic() || method.isStatic())
+        if (!method.isPublic() || method.isStatic() || 0 != (method.getModifiers () & Opcodes.ACC_SYNTHETIC))
             return;
 
         if (!method.getAnnotations(DEPRECATED_TYPE).isEmpty() && !deprecated)