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20b1dadf92
stabilize Strict Provenance and Exposed Provenance APIs Given that [RFC 3559](https://rust-lang.github.io/rfcs/3559-rust-has-provenance.html) has been accepted, t-lang has approved the concept of provenance to exist in the language. So I think it's time that we stabilize the strict provenance and exposed provenance APIs, and discuss provenance explicitly in the docs: ```rust // core::ptr pub const fn without_provenance<T>(addr: usize) -> *const T; pub const fn dangling<T>() -> *const T; pub const fn without_provenance_mut<T>(addr: usize) -> *mut T; pub const fn dangling_mut<T>() -> *mut T; pub fn with_exposed_provenance<T>(addr: usize) -> *const T; pub fn with_exposed_provenance_mut<T>(addr: usize) -> *mut T; impl<T: ?Sized> *const T { pub fn addr(self) -> usize; pub fn expose_provenance(self) -> usize; pub fn with_addr(self, addr: usize) -> Self; pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self; } impl<T: ?Sized> *mut T { pub fn addr(self) -> usize; pub fn expose_provenance(self) -> usize; pub fn with_addr(self, addr: usize) -> Self; pub fn map_addr(self, f: impl FnOnce(usize) -> usize) -> Self; } impl<T: ?Sized> NonNull<T> { pub fn addr(self) -> NonZero<usize>; pub fn with_addr(self, addr: NonZero<usize>) -> Self; pub fn map_addr(self, f: impl FnOnce(NonZero<usize>) -> NonZero<usize>) -> Self; } ``` I also did a pass over the docs to adjust them, because this is no longer an "experiment". The `ptr` docs now discuss the concept of provenance in general, and then they go into the two families of APIs for dealing with provenance: Strict Provenance and Exposed Provenance. I removed the discussion of how pointers also have an associated "address space" -- that is not actually tracked in the pointer value, it is tracked in the type, so IMO it just distracts from the core point of provenance. I also adjusted the docs for `with_exposed_provenance` to make it clear that we cannot guarantee much about this function, it's all best-effort. There are two unstable lints associated with the strict_provenance feature gate; I moved them to a new [strict_provenance_lints](https://github.com/rust-lang/rust/issues/130351) feature since I didn't want this PR to have an even bigger FCP. ;) `@rust-lang/opsem` Would be great to get some feedback on the docs here. :) Nominating for `@rust-lang/libs-api.` Part of https://github.com/rust-lang/rust/issues/95228. [FCP comment](https://github.com/rust-lang/rust/pull/130350#issuecomment-2395114536) |
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