From 48fbe38f69300813e2adf4c8ab63f76d9b426bf9 Mon Sep 17 00:00:00 2001 From: LegionMammal978 Date: Thu, 4 Jan 2024 10:39:31 -0500 Subject: [PATCH] Rename `pointer` field on `Pin` The internal, unstable field of `Pin` can conflict with fields from the inner type accessed via the `Deref` impl. Rename it from `pointer` to `__pointer`, to make it less likely to conflict with anything else. --- library/core/src/pin.rs | 46 +++++++++++-------- .../feature-gate-unsafe_pin_internals.rs | 2 +- tests/ui/pin-macro/cant_access_internals.rs | 2 +- .../ui/pin-macro/cant_access_internals.stderr | 4 +- 4 files changed, 30 insertions(+), 24 deletions(-) diff --git a/library/core/src/pin.rs b/library/core/src/pin.rs index 7d8c881eab809..b7a107ba2d4b5 100644 --- a/library/core/src/pin.rs +++ b/library/core/src/pin.rs @@ -411,14 +411,20 @@ pub struct Pin

{ // - deter downstream users from accessing it (which would be unsound!), // - let the `pin!` macro access it (such a macro requires using struct // literal syntax in order to benefit from lifetime extension). - // Long-term, `unsafe` fields or macro hygiene are expected to offer more robust alternatives. + // + // However, if `P::Deref` exposes a field with the same name as this field, + // then the two will collide, resulting in a confusing error when the user + // attempts to access the field through a `Pin

`. Therefore, the name + // `__pointer` is designed to be unlikely to collide with any other + // field. Long-term, macro hygiene is expected to offer a more robust + // alternative, alongside `unsafe` fields. #[unstable(feature = "unsafe_pin_internals", issue = "none")] #[doc(hidden)] - pub pointer: P, + pub __pointer: P, } // The following implementations aren't derived in order to avoid soundness -// issues. `&self.pointer` should not be accessible to untrusted trait +// issues. `&self.__pointer` should not be accessible to untrusted trait // implementations. // // See for more details. @@ -525,7 +531,7 @@ impl> Pin

{ #[rustc_const_unstable(feature = "const_pin", issue = "76654")] #[stable(feature = "pin_into_inner", since = "1.39.0")] pub const fn into_inner(pin: Pin

) -> P { - pin.pointer + pin.__pointer } } @@ -654,7 +660,7 @@ impl Pin

{ #[rustc_const_unstable(feature = "const_pin", issue = "76654")] #[stable(feature = "pin", since = "1.33.0")] pub const unsafe fn new_unchecked(pointer: P) -> Pin

{ - Pin { pointer } + Pin { __pointer: pointer } } /// Gets a pinned shared reference from this pinned pointer. @@ -668,7 +674,7 @@ impl Pin

{ #[inline(always)] pub fn as_ref(&self) -> Pin<&P::Target> { // SAFETY: see documentation on this function - unsafe { Pin::new_unchecked(&*self.pointer) } + unsafe { Pin::new_unchecked(&*self.__pointer) } } /// Unwraps this `Pin

` returning the underlying pointer. @@ -688,7 +694,7 @@ impl Pin

{ #[rustc_const_unstable(feature = "const_pin", issue = "76654")] #[stable(feature = "pin_into_inner", since = "1.39.0")] pub const unsafe fn into_inner_unchecked(pin: Pin

) -> P { - pin.pointer + pin.__pointer } } @@ -725,7 +731,7 @@ impl Pin

{ #[inline(always)] pub fn as_mut(&mut self) -> Pin<&mut P::Target> { // SAFETY: see documentation on this function - unsafe { Pin::new_unchecked(&mut *self.pointer) } + unsafe { Pin::new_unchecked(&mut *self.__pointer) } } /// Assigns a new value to the memory behind the pinned reference. @@ -750,7 +756,7 @@ impl Pin

{ where P::Target: Sized, { - *(self.pointer) = value; + *(self.__pointer) = value; } } @@ -776,7 +782,7 @@ impl<'a, T: ?Sized> Pin<&'a T> { U: ?Sized, F: FnOnce(&T) -> &U, { - let pointer = &*self.pointer; + let pointer = &*self.__pointer; let new_pointer = func(pointer); // SAFETY: the safety contract for `new_unchecked` must be @@ -806,7 +812,7 @@ impl<'a, T: ?Sized> Pin<&'a T> { #[rustc_const_unstable(feature = "const_pin", issue = "76654")] #[stable(feature = "pin", since = "1.33.0")] pub const fn get_ref(self) -> &'a T { - self.pointer + self.__pointer } } @@ -817,7 +823,7 @@ impl<'a, T: ?Sized> Pin<&'a mut T> { #[rustc_const_unstable(feature = "const_pin", issue = "76654")] #[stable(feature = "pin", since = "1.33.0")] pub const fn into_ref(self) -> Pin<&'a T> { - Pin { pointer: self.pointer } + Pin { __pointer: self.__pointer } } /// Gets a mutable reference to the data inside of this `Pin`. @@ -837,7 +843,7 @@ impl<'a, T: ?Sized> Pin<&'a mut T> { where T: Unpin, { - self.pointer + self.__pointer } /// Gets a mutable reference to the data inside of this `Pin`. @@ -855,7 +861,7 @@ impl<'a, T: ?Sized> Pin<&'a mut T> { #[stable(feature = "pin", since = "1.33.0")] #[rustc_const_unstable(feature = "const_pin", issue = "76654")] pub const unsafe fn get_unchecked_mut(self) -> &'a mut T { - self.pointer + self.__pointer } /// Construct a new pin by mapping the interior value. @@ -978,21 +984,21 @@ impl Receiver for Pin

{} #[stable(feature = "pin", since = "1.33.0")] impl fmt::Debug for Pin

{ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Debug::fmt(&self.pointer, f) + fmt::Debug::fmt(&self.__pointer, f) } } #[stable(feature = "pin", since = "1.33.0")] impl fmt::Display for Pin

{ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Display::fmt(&self.pointer, f) + fmt::Display::fmt(&self.__pointer, f) } } #[stable(feature = "pin", since = "1.33.0")] impl fmt::Pointer for Pin

{ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Pointer::fmt(&self.pointer, f) + fmt::Pointer::fmt(&self.__pointer, f) } } @@ -1235,16 +1241,16 @@ pub macro pin($value:expr $(,)?) { // instead, dropped _at the end of the enscoping block_. // For instance, // ```rust - // let p = Pin { pointer: &mut }; + // let p = Pin { __pointer: &mut }; // ``` // becomes: // ```rust // let mut anon = ; - // let p = Pin { pointer: &mut anon }; + // let p = Pin { __pointer: &mut anon }; // ``` // which is *exactly* what we want. // // See https://doc.rust-lang.org/1.58.1/reference/destructors.html#temporary-lifetime-extension // for more info. - $crate::pin::Pin::<&mut _> { pointer: &mut { $value } } + $crate::pin::Pin::<&mut _> { __pointer: &mut { $value } } } diff --git a/tests/ui/feature-gates/feature-gate-unsafe_pin_internals.rs b/tests/ui/feature-gates/feature-gate-unsafe_pin_internals.rs index 134ea25b75afb..594a2672d435d 100644 --- a/tests/ui/feature-gates/feature-gate-unsafe_pin_internals.rs +++ b/tests/ui/feature-gates/feature-gate-unsafe_pin_internals.rs @@ -7,7 +7,7 @@ use core::{marker::PhantomPinned, pin::Pin}; /// The `unsafe_pin_internals` is indeed unsound. fn non_unsafe_pin_new_unchecked(pointer: &mut T) -> Pin<&mut T> { - Pin { pointer } + Pin { __pointer: pointer } } fn main() { diff --git a/tests/ui/pin-macro/cant_access_internals.rs b/tests/ui/pin-macro/cant_access_internals.rs index 5826a18b5718b..4aeb6a643d959 100644 --- a/tests/ui/pin-macro/cant_access_internals.rs +++ b/tests/ui/pin-macro/cant_access_internals.rs @@ -8,5 +8,5 @@ use core::{ fn main() { let mut phantom_pinned = pin!(PhantomPinned); - mem::take(phantom_pinned.pointer); //~ ERROR use of unstable library feature 'unsafe_pin_internals' + mem::take(phantom_pinned.__pointer); //~ ERROR use of unstable library feature 'unsafe_pin_internals' } diff --git a/tests/ui/pin-macro/cant_access_internals.stderr b/tests/ui/pin-macro/cant_access_internals.stderr index 9af1cd2a16c93..fce8d4999d48e 100644 --- a/tests/ui/pin-macro/cant_access_internals.stderr +++ b/tests/ui/pin-macro/cant_access_internals.stderr @@ -1,8 +1,8 @@ error[E0658]: use of unstable library feature 'unsafe_pin_internals' --> $DIR/cant_access_internals.rs:11:15 | -LL | mem::take(phantom_pinned.pointer); - | ^^^^^^^^^^^^^^^^^^^^^^ +LL | mem::take(phantom_pinned.__pointer); + | ^^^^^^^^^^^^^^^^^^^^^^^^ | = help: add `#![feature(unsafe_pin_internals)]` to the crate attributes to enable