Module blog::daily_rfcs::ffi::_0068_const_unsafe_pointers
source · [−]Expand description
Rename *T to *const T.
Note
| Rust | C |
|---|---|
*mut T | T* |
*const T | const T* |
Valid coercion
&'a T ==> *const T | &'a mut T ==> *mut T | |
|---|---|---|
rustc | the memory will remain valid for the lifetime 'a and the memory will be immutable up to memory stored in Unsafe<U> | the memory will stay valid during ’a and that the memory will not be accessed during 'a, and will consume the &'a mut T during the coercion |
code | the pointer is only dereferenced in the lifetime 'a | the unsafe pointer is only dereferenced in the lifetime 'a, and that the memory is “valid again” after 'a |
Valid cast
*mut T ==> &’a mut T | *const T ==> &'a T |
|---|---|
the memory is initialized to start out with and that nobody will access the memory during 'a except for the converted pointer | the memory is initialized to start out with and that nobody will write to the pointer during 'a except for memory within Unsafe<U> |