fix: test for #[thrust::predicate]

Author: coeff-aij

tests/ui/pass/annot_preds.rs

@@ -3,22 +3,19 @@
 
 #[thrust::predicate]
 fn is_double(x: i64, doubled_x: i64) -> bool {
-    x * 2 == doubled_x
-    // "(=(
-    //     (* (x 2))
-    //     doubled_x
-    // ))"
+    "(=
+        (* x 2)
+        doubled_x
+    )"; true
 }
 
 #[thrust::requires(true)]
-#[thrust::ensures(result == 2 * x)]
-// #[thrust::ensures(is_double(x, result))]
+#[thrust::ensures(is_double(x, result))]
 fn double(x: i64) -> i64 {
     x + x
 }
 
 fn main() {
     let a = 3;
     assert!(double(a) == 6);
-    assert!(is_double(a, double(a)));
 }