1 files changed, 41 insertions, 1 deletions

diff --git a/src/core/lombok/bytecode/FixedClassWriter.java b/src/core/lombok/bytecode/FixedClassWriter.java
index 42d8c4c1..528bc79d 100644
--- a/src/core/lombok/bytecode/FixedClassWriter.java
+++ b/src/core/lombok/bytecode/FixedClassWriter.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2010 The Project Lombok Authors.
+ * Copyright (C) 2010-2012 The Project Lombok Authors.
  * 
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -21,6 +21,9 @@
  */
 package lombok.bytecode;
 
+import java.io.InputStream;
+import java.util.Arrays;
+
 import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.ClassWriter;
 
@@ -36,6 +39,43 @@ class FixedClassWriter extends ClassWriter {
 			return super.getCommonSuperClass(type1, type2);
 		} catch (Exception e) {
 			return "java/lang/Object";
+		} catch (ClassFormatError e) {
+			ClassLoader cl = this.getClass().getClassLoader();
+			if (cl == null) cl = ClassLoader.getSystemClassLoader();
+			String message = debugCheckClassFormatErrorIssue(cl, type1) +
+					debugCheckClassFormatErrorIssue(cl, type2);
+			throw new ClassFormatError(message);
+		}
+	}
+	
+	
+	// This is debug-aiding code in an attempt to find the cause of issue:
+	// http://code.google.com/p/projectlombok/issues/detail?id=339
+	private static String debugCheckClassFormatErrorIssue(ClassLoader cl, String type) {
+		try {
+			Class.forName(type.replace('/', '.'), false, cl);
+			return String.format("Class.forName debug on %s: no issues\n", type);
+		} catch (ClassFormatError e) {
+			// expected
+		} catch (Throwable e) {
+			return String.format("Class.forName debug on %s: Exception: %s\n", type, e);
+		}
+		
+		try {
+			InputStream in = cl.getResourceAsStream(type + ".class");
+			if (in == null) return String.format("Class.forName debug on %s: Can't find resource %s\n", type, type + ".class");
+			try {
+				int[] firstBytes = new int[4];
+				for (int i = 0; i < 4; i++) firstBytes[0] = in.read();
+				if (firstBytes[0] == -1) return String.format("Class.forName debug on %s: file size is 0\n", type);
+				if (firstBytes[3] == -1) return String.format("Class.forName debug on %s: Less than 4 bytes in class file\n", type);
+				if (!Arrays.equals(new int[] {0xCA, 0xFE, 0xBA, 0xBE}, firstBytes)) return String.format("Class.forName debug on %s: no CAFEBABE: %s\n", type, Arrays.toString(firstBytes));
+				return String.format("Class.forName debug on %s: No immediately obvious reason for failure found\n", type);
+			} finally {
+				in.close();
+			}
+		} catch (Throwable e) {
+			return String.format("Class.forName debug on %s: Can't read as stream: %s\n", type, e);
 		}
 	}
 }
\ No newline at end of file