use also ref.cast for every cast.

src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java

@@ -1435,6 +1435,11 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
             case NEW_WITH_RTT:
                 opCode = STRUCT_NEW_DEFAULT;
                 break;
+            case CAST:
+                codeStream.writeOpCode( REF_CAST );
+                codeStream.writeValueType( options.types.valueOf( "java/lang/Object" ) );
+                codeStream.writeValueType( type );
+                return;
             default:
                 throw new Error( "Unknown operator: " + op );
         }

src/de/inetsoftware/jwebassembly/binary/InstructionOpcodes.java

@@ -513,4 +513,6 @@ interface InstructionOpcodes {
     static final int ARRAY_LEN              = 0xFB17;
 
     static final int RTT_CANON              = 0xFB30;
+
+    static final int REF_CAST               = 0xFB41;
 }

src/de/inetsoftware/jwebassembly/module/WasmStructInstruction.java

@@ -228,6 +228,10 @@ class WasmStructInstruction extends WasmInstruction {
                 writer.writeConst( idx, ValueType.i32 );
             }
             writer.writeFunctionCall( functionName, null );
+            if( op == StructOperator.CAST && options.useGC() ) {
+                writer.writeStructOperator( StructOperator.RTT_CANON, type, null, -1 );
+                writer.writeStructOperator( op, type, null, -1 );
+            }
         } else {
             writer.writeStructOperator( op, type, fieldName, idx );
         }

src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java

@@ -915,6 +915,9 @@ public class TextModuleWriter extends ModuleWriter {
             case NEW_WITH_RTT:
                 operation = "struct.new_with_rtt";
                 break;
+            case CAST:
+                operation = "ref.cast $java/lang/Object";
+                break;
             default:
                 throw new Error( "Unknown operator: " + op );
         }