Fix transformers causing NCDF on specific servers (AE2-UEL#374)

Author: GlodBlock

src/main/java/appeng/core/transformer/AE2ELTransformer.java

@@ -24,14 +24,19 @@
 import com.google.common.collect.Sets;
 import com.google.common.io.ByteStreams;
 import net.minecraft.launchwrapper.IClassTransformer;
+import net.minecraft.launchwrapper.Launch;
 import net.minecraftforge.fml.common.Loader;
 import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.ClassVisitor;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.commons.ClassRemapper;
 import org.objectweb.asm.commons.Remapper;
-import org.objectweb.asm.tree.*;
+import org.objectweb.asm.tree.AbstractInsnNode;
+import org.objectweb.asm.tree.ClassNode;
+import org.objectweb.asm.tree.FieldNode;
+import org.objectweb.asm.tree.MethodInsnNode;
+import org.objectweb.asm.tree.MethodNode;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -48,7 +53,7 @@ public byte[] transform(String name, String transformedName, byte[] basicClass)
 
         if ("net.minecraftforge.common.ForgeHooks".equals(transformedName)) {
             ClassReader cr = new ClassReader(basicClass);
-            ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
+            ClassWriter cw = new SafeClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
             ClassVisitor cv = new PickBlockPatch(cw);
             cr.accept(cv, ClassReader.EXPAND_FRAMES);
             return cw.toByteArray();
@@ -188,4 +193,39 @@ public String map(final String name) {
 
     }
 
+    private static class SafeClassWriter extends ClassWriter {
+
+        public SafeClassWriter(int flags) {
+            super(flags);
+        }
+
+        @Override
+        protected String getCommonSuperClass(final String type1, final String type2) {
+            Class<?> c, d;
+            // clueless
+            ClassLoader classLoader = Launch.classLoader;
+            try {
+                c = Class.forName(type1.replace('/', '.'), false, classLoader);
+                d = Class.forName(type2.replace('/', '.'), false, classLoader);
+            } catch (Exception e) {
+                throw new RuntimeException(e.toString());
+            }
+            if (c.isAssignableFrom(d)) {
+                return type1;
+            }
+            if (d.isAssignableFrom(c)) {
+                return type2;
+            }
+            if (c.isInterface() || d.isInterface()) {
+                return "java/lang/Object";
+            } else {
+                do {
+                    c = c.getSuperclass();
+                } while (!c.isAssignableFrom(d));
+                return c.getName().replace('.', '/');
+            }
+        }
+
+    }
+
 }