Overflows only panic in debug mode

src/test/run-fail/promoted_overflow.rs

@@ -11,6 +11,7 @@
 #![allow(const_err)]
 
 // error-pattern: overflow
+// compile-flags: -C overflow-checks=yes
 
 fn main() {
     let x: &'static u32 = &(0u32 - 1);