auto merge of #16350 : hirschenberger/rust/issue-15917, r=alexcrichton

Adding test for issue #15917 which was previously fixed with #15709

src/test/compile-fail/repeat_count.rs

@@ -23,4 +23,6 @@ fn main() {
     //~^ ERROR: expected `uint` but found `&'static str`
     let f = [0, ..-4];
     //~^ ERROR expected positive integer for repeat count but found negative integer
+    let f = [0u, ..-1];
+    //~^ ERROR expected positive integer for repeat count but found negative integer
 }