compile-fail tests don't like warnings

Author: Oliver 'ker' Schneider

src/test/compile-fail/array_const_index-0.rs

@@ -8,8 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-static a: &'static [i32] = &[];
-static b: i32 = (&a)[1]; //~ ERROR: array index out of bounds
+static A: &'static [i32] = &[];
+static B: i32 = (&A)[1]; //~ ERROR: array index out of bounds
 //~^ ERROR: constant indexing failed
 
-fn main() {}
+fn main() {
+    let _ = B;
+}