main_with_local_string_class should be invalid, see comment why

semantic/main_with_local_string_class.invalid.java

+/* String shadows the default String class.
+ * javac won't complain because the proper main method could be defined in another class file.
+ * However, since MiniJava files contain the entire program, it is reasonable to expect
+ * that the lack of a proper main method be detected at compile time.
+ * Analogy:
+ * If gcc is invoked _without_ '-c' on a set of .c files, gcc will also invoke the linker.
+ * If the linker cannot find a main, the gcc "user experience" is equivalent to a compiler error.
+ */
+class String { }
+
+class MainWithLocalStringShadowingJavaString {
+    public static void main(String[] args) {}
+}
+

semantic/main_with_local_string_class_compiles.java

-/* String shadows the default String class.
- * However, Java only detects the lack of a main() at runtime,
- * failing with 'error: Main method not found'
- */
-class String { }
-
-class MainWithLocalStringShadowingJavaString {
-    public static void main(String[] args) {}
-}
-