Change intrinsics tests to ensure the call is not removed by the compiler (#2552)

The tests below started failing as part of the latest toolchain update because the value produced by intrinsics is not used, and the compiler just removes them.

To avoid that to happen, we now wrap those calls with the black_box std function to avoid compiler optimizations.

Author: celinval

tests/kani/Intrinsics/Math/Arith/Unchecked/add_fail.rs

@@ -9,5 +9,6 @@
 fn main() {
     let a: i32 = kani::any();
     let b: i32 = kani::any();
-    unsafe { std::intrinsics::unchecked_add(a, b) };
+    // Black box this so it doesn't get pruned by the compiler.
+    std::hint::black_box(unsafe { std::intrinsics::unchecked_add(a, b) });
 }

tests/kani/Intrinsics/Math/Arith/Unchecked/div_fail.rs

@@ -10,5 +10,6 @@
 fn main() {
     let a: i32 = i32::MIN;
     let b: i32 = -1;
-    unsafe { std::intrinsics::unchecked_div(a, b) };
+    // Black box this so it doesn't get pruned by the compiler.
+    std::hint::black_box(unsafe { std::intrinsics::unchecked_div(a, b) });
 }

tests/kani/Intrinsics/Math/Arith/Unchecked/div_zero_fail.rs

@@ -10,5 +10,6 @@
 fn main() {
     let a: i32 = kani::any();
     let b: i32 = 0;
-    unsafe { std::intrinsics::unchecked_div(a, b) };
+    // Black box this so it doesn't get pruned by the compiler.
+    std::hint::black_box(unsafe { std::intrinsics::unchecked_div(a, b) });
 }

tests/kani/Intrinsics/Math/Arith/Unchecked/mul_fail.rs

@@ -9,5 +9,6 @@
 fn main() {
     let a: i32 = kani::any();
     let b: i32 = kani::any();
-    unsafe { std::intrinsics::unchecked_mul(a, b) };
+    // Black box this so it doesn't get pruned by the compiler.
+    std::hint::black_box(unsafe { std::intrinsics::unchecked_mul(a, b) });
 }

tests/kani/Intrinsics/Math/Arith/Unchecked/rem_fail.rs

@@ -10,5 +10,6 @@
 fn main() {
     let a: i32 = i32::MIN;
     let b: i32 = -1;
-    unsafe { std::intrinsics::unchecked_rem(a, b) };
+    // Black box this so it doesn't get pruned by the compiler.
+    std::hint::black_box(unsafe { std::intrinsics::unchecked_rem(a, b) });
 }

tests/kani/Intrinsics/Math/Arith/Unchecked/rem_zero_fail.rs

@@ -10,5 +10,6 @@
 fn main() {
     let a: i32 = kani::any();
     let b: i32 = 0;
-    unsafe { std::intrinsics::unchecked_rem(a, b) };
+    // Black box this so it doesn't get pruned by the compiler.
+    std::hint::black_box(unsafe { std::intrinsics::unchecked_rem(a, b) });
 }

tests/kani/Intrinsics/Math/Arith/Unchecked/shl_fail.rs

@@ -9,5 +9,6 @@
 fn main() {
     let a: u32 = kani::any();
     let b: u32 = kani::any();
-    unsafe { std::intrinsics::unchecked_shl(a, b) };
+    // Black box this so it doesn't get pruned by the compiler.
+    std::hint::black_box(unsafe { std::intrinsics::unchecked_shl(a, b) });
 }

tests/kani/Intrinsics/Math/Arith/Unchecked/shr_fail.rs

@@ -9,5 +9,6 @@
 fn main() {
     let a: u32 = kani::any();
     let b: u32 = kani::any();
-    unsafe { std::intrinsics::unchecked_shr(a, b) };
+    // Black box this so it doesn't get pruned by the compiler.
+    std::hint::black_box(unsafe { std::intrinsics::unchecked_shr(a, b) });
 }

tests/kani/Intrinsics/Math/Arith/Unchecked/sub_fail.rs

@@ -9,5 +9,6 @@
 fn main() {
     let a: i32 = kani::any();
     let b: i32 = kani::any();
-    unsafe { std::intrinsics::unchecked_sub(a, b) };
+    // Black box this so it doesn't get pruned by the compiler.
+    std::hint::black_box(unsafe { std::intrinsics::unchecked_sub(a, b) });
 }