Allow uses of interface types to verify.

�
	Allow uses of interface types to verify.  This is not really
	type-safe, but it matches what Sun does, and is OK as long as
	there are appropriate run-time checks.
	* verify.c (merge_types):  If merging two interface types,
	just set the result to java.lang.Object.
	* expr.c (pop_type):  Any interface is matches by java.lang.Object.

From-SVN: r23656

gcc/java/expr.c

@@ -268,6 +268,12 @@ pop_type (type)
 	return type;
       else if (can_widen_reference_to (t, type))
 	return t;
+      /* This is a kludge, but matches what Sun's verifier does.
+	 It can be tricked, but is safe as long as type errors
+	 (i.e. interface method calls) are caught at run-time. */
+      else if (CLASS_INTERFACE (TYPE_NAME (TREE_TYPE (type)))
+	       && t == object_ptr_type_node)
+	return t;
     }
   error ("unexpected type on stack");
   return t;

gcc/java/verify.c

@@ -150,6 +150,32 @@ merge_types (type1, type2)
 	    }
 	  return object_ptr_type_node;
 	}
+
+      if (CLASS_INTERFACE (TYPE_NAME (tt1)))
+	{
+	  if (CLASS_INTERFACE (TYPE_NAME (tt2)))
+	    {
+	      /* This is a kludge, but matches what Sun's verifier does.
+		 It can be tricked, but is safe as long as type errors
+		 (i.e. interface method calls) are caught at run-time. */
+	      return object_ptr_type_node;
+	    }
+	  else
+	    {
+	      if (can_widen_reference_to (tt2, tt1))
+		return type1;
+	      else
+		return TYPE_UNKNOWN;
+	    }
+	}
+      else if (CLASS_INTERFACE (TYPE_NAME (tt2)))
+	{
+	  if (can_widen_reference_to (tt1, tt2))
+	    return type2;
+	  else
+	    return TYPE_UNKNOWN;
+	}
+
       type1 = tt1;
       type2 = tt2;