test for pointer wrapping ICE

Author: RalfJung

tests/run-pass/ptr_arith_offset_overflow.rs

@@ -1,9 +1,12 @@
+use std::ptr;
+
 fn main() {
     let v = [1i16, 2];
-    let x = v.as_ptr().wrapping_offset(1); // ptr to the 2nd element
+    let x = &mut ptr::null(); // going through memory as there are more sanity checks along that path
+    *x = v.as_ptr().wrapping_offset(1); // ptr to the 2nd element
     // Adding 2*isize::max and then 1 is like substracting 1
-    let x = x.wrapping_offset(isize::max_value());
-    let x = x.wrapping_offset(isize::max_value());
-    let x = x.wrapping_offset(1);
-    assert_eq!(unsafe { *x }, 1);
+    *x = x.wrapping_offset(isize::max_value());
+    *x = x.wrapping_offset(isize::max_value());
+    *x = x.wrapping_offset(1);
+    assert_eq!(unsafe { **x }, 1);
 }

tests/run-pass/ptr_int_casts.rs

@@ -1,4 +1,5 @@
 use std::mem;
+use std::ptr;
 
 fn eq_ref<T>(x: &T, y: &T) -> bool {
     x as *const _ == y as *const _
@@ -11,6 +12,12 @@ fn main() {
     assert_eq!(1 as *const i32 as usize, 1);
     assert_eq!((1 as *const i32).wrapping_offset(4) as usize, 1 + 4*4);
 
+    // negative overflowing wrapping_offset (going through memory because
+    // this used to trigger an ICE on 32bit)
+    let val = &mut ptr::null();
+    *val = (1 as *const u8).wrapping_offset(-4);
+    assert_eq!(*val as usize, usize::max_value() - 2);
+
     {   // ptr-int-ptr
         let x = 13;
         let mut y = &x as &_ as *const _ as usize;