do not use int2ptr casts in strict provenance tests

Author: RalfJung

tests/fail/provenance/strict-provenance-offset.rs renamed to tests/fail/provenance/ptr_invalid_offset.rs

@@ -1,9 +1,11 @@
 // compile-flags: -Zmiri-strict-provenance
 // error-pattern: not a valid pointer
+#![feature(strict_provenance)]
 
 fn main() {
     let x = 22;
     let ptr = &x as *const _ as *const u8;
-    let roundtrip = ptr as usize as *const u8;
+    let roundtrip = std::ptr::invalid::<u8>(ptr as usize);
+    // Not even offsetting this is allowed.
     let _ = unsafe { roundtrip.offset(1) };
 }

tests/fail/provenance/strict-provenance-offset.stderr renamed to tests/fail/provenance/ptr_invalid_offset.stderr

@@ -8,8 +8,8 @@ LL |         unsafe { intrinsics::offset(self, count) }
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
 
    = note: inside `std::ptr::const_ptr::<impl *const u8>::offset` at RUSTLIB/core/src/ptr/const_ptr.rs:LL:CC
-note: inside `main` at $DIR/strict-provenance-offset.rs:LL:CC
-  --> $DIR/strict-provenance-offset.rs:LL:CC
+note: inside `main` at $DIR/ptr_invalid_offset.rs:LL:CC
+  --> $DIR/ptr_invalid_offset.rs:LL:CC
    |
 LL |     let _ = unsafe { roundtrip.offset(1) };
    |                      ^^^^^^^^^^^^^^^^^^^

tests/pass/slices.rs

@@ -3,8 +3,10 @@
 #![feature(slice_as_chunks)]
 #![feature(slice_partition_dedup)]
 #![feature(layout_for_ptr)]
+#![feature(strict_provenance)]
 
 use std::slice;
+use std::ptr;
 
 fn slice_of_zst() {
     fn foo<T>(v: &[T]) -> Option<&[T]> {
@@ -25,7 +27,7 @@ fn slice_of_zst() {
 
     // In a slice of zero-size elements the pointer is meaningless.
     // Ensure iteration still works even if the pointer is at the end of the address space.
-    let slice: &[()] = unsafe { slice::from_raw_parts(-5isize as *const (), 10) };
+    let slice: &[()] = unsafe { slice::from_raw_parts(ptr::invalid(-5isize as usize), 10) };
     assert_eq!(slice.len(), 10);
     assert_eq!(slice.iter().count(), 10);
 
@@ -38,7 +40,7 @@ fn slice_of_zst() {
     assert!(foo(slice).is_some());
 
     // Test mutable iterators as well
-    let slice: &mut [()] = unsafe { slice::from_raw_parts_mut(-5isize as *mut (), 10) };
+    let slice: &mut [()] = unsafe { slice::from_raw_parts_mut(ptr::invalid_mut(-5isize as usize), 10) };
     assert_eq!(slice.len(), 10);
     assert_eq!(slice.iter_mut().count(), 10);
 
@@ -254,7 +256,7 @@ fn test_for_invalidated_pointers() {
 fn large_raw_slice() {
     let size = isize::MAX as usize;
     // Creating a raw slice of size isize::MAX and asking for its size is okay.
-    let s = std::ptr::slice_from_raw_parts(1usize as *const u8, size);
+    let s = std::ptr::slice_from_raw_parts(ptr::invalid::<u8>(1), size);
     assert_eq!(size, unsafe { std::mem::size_of_val_raw(s) });
 }