new, simpler approach to the iter library

src/test/compile-fail/lub-in-args.rs

@@ -0,0 +1,17 @@
+fn two_args<T>(x: T, y: T) { }
+
+fn main() {
+    let x: [mut int] = [mut 3];
+    let y: [int] = [3];
+    let a: @mut int = @mut 3;
+    let b: @int = @3;
+
+    // NOTE:
+    //
+    // The fact that this test fails to compile reflects a known
+    // shortcoming of the current inference algorithm.  These errors
+    // are *not* desirable.
+
+    two_args(x, y); //! ERROR (values differ in mutability)
+    two_args(a, b); //! ERROR (values differ in mutability)
+}