diff options
| -rw-r--r-- | library/core/src/ptr/mut_ptr.rs | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs index bbcc7c699e0..0bb2566fd4c 100644 --- a/library/core/src/ptr/mut_ptr.rs +++ b/library/core/src/ptr/mut_ptr.rs @@ -80,10 +80,14 @@ impl<T: ?Sized> *mut T { #[unstable(feature = "set_ptr_value", issue = "75091")] #[must_use = "returns a new pointer rather than modifying its argument"] #[inline] - pub fn with_metadata_of<U>(self, mut val: *mut U) -> *mut U + pub fn with_metadata_of<U>(self, val: *const U) -> *mut U where U: ?Sized, { + // Prepare in the type system that we will replace the pointer value with a mutable + // pointer, taking the mutable provenance from the `self` pointer. + let mut val = val as *mut U; + // Pointer to the pointer value within the value. let target = &mut val as *mut *mut U as *mut *mut u8; // SAFETY: In case of a thin pointer, this operations is identical // to a simple assignment. In case of a fat pointer, with the current |