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make ptr::invalid not the same as a regular int2ptr cast

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This commit is contained in:
Ralf Jung 2022-05-20 17:16:41 +02:00
parent 512a328e2f
commit 31c3c04498
1 changed files with 10 additions and 2 deletions
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12
library/core/src/ptr/mod.rs
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@ -555,7 +555,11 @@ pub const fn null_mut<T>() -> *mut T {
#[unstable(feature = "strict_provenance", issue = "95228")]
pub const fn invalid<T>(addr: usize) -> *const T {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
addr as *const T
// We use transmute rather than a cast so tools like Miri can tell that this
// is *not* the same as from_exposed_addr.
// SAFETY: every valid integer is also a valid pointer (as long as you don't dereference that
// pointer).
unsafe { mem::transmute(addr) }
}
/// Creates an invalid mutable pointer with the given address.
@ -582,7 +586,11 @@ pub const fn invalid<T>(addr: usize) -> *const T {
#[unstable(feature = "strict_provenance", issue = "95228")]
pub const fn invalid_mut<T>(addr: usize) -> *mut T {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
addr as *mut T
// We use transmute rather than a cast so tools like Miri can tell that this
// is *not* the same as from_exposed_addr.
// SAFETY: every valid integer is also a valid pointer (as long as you don't dereference that
// pointer).
unsafe { mem::transmute(addr) }
}
/// Convert an address back to a pointer, picking up a previously 'exposed' provenance.