Rollup merge of #128277 - RalfJung:offset_from_wildcard, r=oli-obk

miri: fix offset_from behavior on wildcard pointers

offset_from wouldn't behave correctly when the "end" pointer was a wildcard pointer (result of an int2ptr cast) just at the end of the allocation. Fix that by expressing the "same allocation" check in terms of two `check_ptr_access_signed` instead of something specific to offset_from, which is both more canonical and works better with wildcard pointers.

The second commit just improves diagnostics: I wanted the "pointer is dangling (has no provenance)" message to say how many bytes of memory it expected to see (since if it were 0 bytes, this would actually be legal, so it's good to tell the user that it's not 0 bytes). And then I was annoying that the error looks so different for when you deref a dangling pointer vs an out-of-bounds pointer so I made them more similar.

Fixes #3767

Author: matthiaskrgr

tests/fail-dep/libc/affinity.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: memory access failed: ALLOC has size 128, so pointer to 129 bytes starting at offset 0 is out-of-bounds
+error: Undefined Behavior: memory access failed: expected a pointer to 129 bytes of memory, but got ALLOC and there are only 128 bytes starting at that pointer
   --> $DIR/affinity.rs:LL:CC
    |
 LL |     let err = unsafe { sched_setaffinity(PID, size_of::<cpu_set_t>() + 1, &cpuset) };
-   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ memory access failed: ALLOC has size 128, so pointer to 129 bytes starting at offset 0 is out-of-bounds
+   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ memory access failed: expected a pointer to 129 bytes of memory, but got ALLOC and there are only 128 bytes starting at that pointer
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail-dep/libc/memchr_null.rs

@@ -3,6 +3,6 @@ use std::ptr;
 // null is explicitly called out as UB in the C docs.
 fn main() {
     unsafe {
-        libc::memchr(ptr::null(), 0, 0); //~ERROR: dangling
+        libc::memchr(ptr::null(), 0, 0); //~ERROR: null pointer
     }
 }

tests/fail-dep/libc/memchr_null.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to some allocation, but got a null pointer
   --> $DIR/memchr_null.rs:LL:CC
    |
 LL |         libc::memchr(ptr::null(), 0, 0);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: expected a pointer to some allocation, but got a null pointer
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail-dep/libc/memcmp_null.rs

@@ -3,6 +3,6 @@ use std::ptr;
 // null is explicitly called out as UB in the C docs.
 fn main() {
     unsafe {
-        libc::memcmp(ptr::null(), ptr::null(), 0); //~ERROR: dangling
+        libc::memcmp(ptr::null(), ptr::null(), 0); //~ERROR: null pointer
     }
 }

tests/fail-dep/libc/memcmp_null.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to some allocation, but got a null pointer
   --> $DIR/memcmp_null.rs:LL:CC
    |
 LL |         libc::memcmp(ptr::null(), ptr::null(), 0);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: expected a pointer to some allocation, but got a null pointer
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail-dep/libc/memcmp_zero.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: 0x2a[noalloc] is a dangling pointer (it has no provenance)
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to some allocation, but got 0x2a[noalloc] which is a dangling pointer (it has no provenance)
   --> $DIR/memcmp_zero.rs:LL:CC
    |
 LL |         libc::memcmp(ptr.cast(), ptr.cast(), 0);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: 0x2a[noalloc] is a dangling pointer (it has no provenance)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: expected a pointer to some allocation, but got 0x2a[noalloc] which is a dangling pointer (it has no provenance)
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail-dep/libc/memcpy_zero.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: 0x17[noalloc] is a dangling pointer (it has no provenance)
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to some allocation, but got 0x17[noalloc] which is a dangling pointer (it has no provenance)
   --> $DIR/memcpy_zero.rs:LL:CC
    |
 LL |         libc::memcpy(to.cast(), from.cast(), 0);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: 0x17[noalloc] is a dangling pointer (it has no provenance)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: expected a pointer to some allocation, but got 0x17[noalloc] which is a dangling pointer (it has no provenance)
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail-dep/libc/memrchr_null.rs

@@ -6,6 +6,6 @@ use std::ptr;
 // null is explicitly called out as UB in the C docs.
 fn main() {
     unsafe {
-        libc::memrchr(ptr::null(), 0, 0); //~ERROR: dangling
+        libc::memrchr(ptr::null(), 0, 0); //~ERROR: null pointer
     }
 }

tests/fail-dep/libc/memrchr_null.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to some allocation, but got a null pointer
   --> $DIR/memrchr_null.rs:LL:CC
    |
 LL |         libc::memrchr(ptr::null(), 0, 0);
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: expected a pointer to some allocation, but got a null pointer
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/both_borrows/issue-miri-1050-1.rs

@@ -1,6 +1,6 @@
 //@revisions: stack tree
 //@[tree]compile-flags: -Zmiri-tree-borrows
-//@error-in-other-file: pointer to 4 bytes starting at offset 0 is out-of-bounds
+//@error-in-other-file: expected a pointer to 4 bytes of memory
 
 fn main() {
     unsafe {

tests/fail/both_borrows/issue-miri-1050-1.stack.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: ALLOC has size 2, so pointer to 4 bytes starting at offset 0 is out-of-bounds
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got ALLOC and there are only 2 bytes starting at that pointer
   --> RUSTLIB/alloc/src/boxed.rs:LL:CC
    |
 LL |         Box(unsafe { Unique::new_unchecked(raw) }, alloc)
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: ALLOC has size 2, so pointer to 4 bytes starting at offset 0 is out-of-bounds
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got ALLOC and there are only 2 bytes starting at that pointer
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/both_borrows/issue-miri-1050-1.tree.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: ALLOC has size 2, so pointer to 4 bytes starting at offset 0 is out-of-bounds
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got ALLOC and there are only 2 bytes starting at that pointer
   --> RUSTLIB/alloc/src/boxed.rs:LL:CC
    |
 LL |         Box(unsafe { Unique::new_unchecked(raw) }, alloc)
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: ALLOC has size 2, so pointer to 4 bytes starting at offset 0 is out-of-bounds
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got ALLOC and there are only 2 bytes starting at that pointer
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/both_borrows/issue-miri-1050-2.stack.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: 0x4[noalloc] is a dangling pointer (it has no provenance)
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got 0x4[noalloc] which is a dangling pointer (it has no provenance)
   --> RUSTLIB/alloc/src/boxed.rs:LL:CC
    |
 LL |         Box(unsafe { Unique::new_unchecked(raw) }, alloc)
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: 0x4[noalloc] is a dangling pointer (it has no provenance)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got 0x4[noalloc] which is a dangling pointer (it has no provenance)
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/both_borrows/issue-miri-1050-2.tree.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: 0x4[noalloc] is a dangling pointer (it has no provenance)
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got 0x4[noalloc] which is a dangling pointer (it has no provenance)
   --> RUSTLIB/alloc/src/boxed.rs:LL:CC
    |
 LL |         Box(unsafe { Unique::new_unchecked(raw) }, alloc)
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: 0x4[noalloc] is a dangling pointer (it has no provenance)
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got 0x4[noalloc] which is a dangling pointer (it has no provenance)
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/dangling_pointers/dangling_pointer_to_raw_pointer.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: 0x10[noalloc] is a dangling pointer (it has no provenance)
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got 0x10[noalloc] which is a dangling pointer (it has no provenance)
   --> $DIR/dangling_pointer_to_raw_pointer.rs:LL:CC
    |
 LL |     unsafe { &(*x).0 as *const i32 }
-   |              ^^^^^^^ out-of-bounds pointer use: 0x10[noalloc] is a dangling pointer (it has no provenance)
+   |              ^^^^^^^ out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got 0x10[noalloc] which is a dangling pointer (it has no provenance)
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/dangling_pointers/deref-invalid-ptr.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: 0x10[noalloc] is a dangling pointer (it has no provenance)
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got 0x10[noalloc] which is a dangling pointer (it has no provenance)
   --> $DIR/deref-invalid-ptr.rs:LL:CC
    |
 LL |     let _y = unsafe { &*x as *const u32 };
-   |                       ^^^ out-of-bounds pointer use: 0x10[noalloc] is a dangling pointer (it has no provenance)
+   |                       ^^^ out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got 0x10[noalloc] which is a dangling pointer (it has no provenance)
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/dangling_pointers/null_pointer_deref.rs

@@ -1,5 +1,5 @@
 #[allow(deref_nullptr)]
 fn main() {
-    let x: i32 = unsafe { *std::ptr::null() }; //~ ERROR: null pointer is a dangling pointer
+    let x: i32 = unsafe { *std::ptr::null() }; //~ ERROR: null pointer
     panic!("this should never print: {}", x);
 }

tests/fail/dangling_pointers/null_pointer_deref.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: memory access failed: null pointer is a dangling pointer (it has no provenance)
+error: Undefined Behavior: memory access failed: expected a pointer to 4 bytes of memory, but got a null pointer
   --> $DIR/null_pointer_deref.rs:LL:CC
    |
 LL |     let x: i32 = unsafe { *std::ptr::null() };
-   |                           ^^^^^^^^^^^^^^^^^ memory access failed: null pointer is a dangling pointer (it has no provenance)
+   |                           ^^^^^^^^^^^^^^^^^ memory access failed: expected a pointer to 4 bytes of memory, but got a null pointer
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/dangling_pointers/null_pointer_write.rs

@@ -1,4 +1,4 @@
 #[allow(deref_nullptr)]
 fn main() {
-    unsafe { *std::ptr::null_mut() = 0i32 }; //~ ERROR: null pointer is a dangling pointer
+    unsafe { *std::ptr::null_mut() = 0i32 }; //~ ERROR: null pointer
 }

tests/fail/dangling_pointers/null_pointer_write.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: memory access failed: null pointer is a dangling pointer (it has no provenance)
+error: Undefined Behavior: memory access failed: expected a pointer to 4 bytes of memory, but got a null pointer
   --> $DIR/null_pointer_write.rs:LL:CC
    |
 LL |     unsafe { *std::ptr::null_mut() = 0i32 };
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ memory access failed: null pointer is a dangling pointer (it has no provenance)
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ memory access failed: expected a pointer to 4 bytes of memory, but got a null pointer
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/dangling_pointers/out_of_bounds_project.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer arithmetic: ALLOC has size 4, so pointer to 8 bytes starting at offset 0 is out-of-bounds
+error: Undefined Behavior: out-of-bounds pointer arithmetic: expected a pointer to 8 bytes of memory, but got ALLOC and there are only 4 bytes starting at that pointer
   --> $DIR/out_of_bounds_project.rs:LL:CC
    |
 LL |         let _field = addr_of!((*ptr).2);
-   |                      ^^^^^^^^^^^^^^^^^^ out-of-bounds pointer arithmetic: ALLOC has size 4, so pointer to 8 bytes starting at offset 0 is out-of-bounds
+   |                      ^^^^^^^^^^^^^^^^^^ out-of-bounds pointer arithmetic: expected a pointer to 8 bytes of memory, but got ALLOC and there are only 4 bytes starting at that pointer
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/dangling_pointers/out_of_bounds_read.rs

@@ -1,6 +1,6 @@
 fn main() {
     let v: Vec<u16> = vec![1, 2];
     // This read is also misaligned. We make sure that the OOB message has priority.
-    let x = unsafe { *v.as_ptr().wrapping_byte_add(5) }; //~ ERROR: out-of-bounds
+    let x = unsafe { *v.as_ptr().wrapping_byte_add(5) }; //~ ERROR: expected a pointer to 2 bytes of memory
     panic!("this should never print: {}", x);
 }

tests/fail/dangling_pointers/out_of_bounds_read.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: memory access failed: ALLOC has size 4, so pointer to 2 bytes starting at offset 5 is out-of-bounds
+error: Undefined Behavior: memory access failed: expected a pointer to 2 bytes of memory, but got ALLOC+0x5 which is at or beyond the end of the allocation of size 4 bytes
   --> $DIR/out_of_bounds_read.rs:LL:CC
    |
 LL |     let x = unsafe { *v.as_ptr().wrapping_byte_add(5) };
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ memory access failed: ALLOC has size 4, so pointer to 2 bytes starting at offset 5 is out-of-bounds
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ memory access failed: expected a pointer to 2 bytes of memory, but got ALLOC+0x5 which is at or beyond the end of the allocation of size 4 bytes
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/dangling_pointers/out_of_bounds_write.rs

@@ -1,5 +1,5 @@
 fn main() {
     let mut v: Vec<u16> = vec![1, 2];
     // This read is also misaligned. We make sure that the OOB message has priority.
-    unsafe { *v.as_mut_ptr().wrapping_byte_add(5) = 0 }; //~ ERROR: out-of-bounds
+    unsafe { *v.as_mut_ptr().wrapping_byte_add(5) = 0 }; //~ ERROR: expected a pointer to 2 bytes of memory
 }

tests/fail/dangling_pointers/out_of_bounds_write.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: memory access failed: ALLOC has size 4, so pointer to 2 bytes starting at offset 5 is out-of-bounds
+error: Undefined Behavior: memory access failed: expected a pointer to 2 bytes of memory, but got ALLOC+0x5 which is at or beyond the end of the allocation of size 4 bytes
   --> $DIR/out_of_bounds_write.rs:LL:CC
    |
 LL |     unsafe { *v.as_mut_ptr().wrapping_byte_add(5) = 0 };
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ memory access failed: ALLOC has size 4, so pointer to 2 bytes starting at offset 5 is out-of-bounds
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ memory access failed: expected a pointer to 2 bytes of memory, but got ALLOC+0x5 which is at or beyond the end of the allocation of size 4 bytes
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/dangling_pointers/storage_dead_dangling.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: out-of-bounds pointer use: $HEX[noalloc] is a dangling pointer (it has no provenance)
+error: Undefined Behavior: out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got $HEX[noalloc] which is a dangling pointer (it has no provenance)
   --> $DIR/storage_dead_dangling.rs:LL:CC
    |
 LL |     let _ref = unsafe { &mut *(LEAK as *mut i32) };
-   |                         ^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: $HEX[noalloc] is a dangling pointer (it has no provenance)
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: expected a pointer to 4 bytes of memory, but got $HEX[noalloc] which is a dangling pointer (it has no provenance)
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information

tests/fail/dangling_pointers/wild_pointer_deref.stderr

@@ -1,8 +1,8 @@
-error: Undefined Behavior: memory access failed: 0x2c[noalloc] is a dangling pointer (it has no provenance)
+error: Undefined Behavior: memory access failed: expected a pointer to 4 bytes of memory, but got 0x2c[noalloc] which is a dangling pointer (it has no provenance)
   --> $DIR/wild_pointer_deref.rs:LL:CC
    |
 LL |     let x = unsafe { *p };
-   |                      ^^ memory access failed: 0x2c[noalloc] is a dangling pointer (it has no provenance)
+   |                      ^^ memory access failed: expected a pointer to 4 bytes of memory, but got 0x2c[noalloc] which is a dangling pointer (it has no provenance)
    |
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information