From 5eef5ee38abbccac368871bef0555fc24b2c53f3 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Sat, 16 Nov 2024 18:32:25 +0100 Subject: [PATCH] stabilize const_ptr_is_null --- compiler/rustc_const_eval/src/const_eval/machine.rs | 6 ++++++ library/core/src/intrinsics/mod.rs | 4 ++-- library/core/src/lib.rs | 1 - library/core/src/ptr/const_ptr.rs | 8 +++++--- library/core/src/ptr/mut_ptr.rs | 6 +++--- library/core/src/ub_checks.rs | 2 +- tests/ui/consts/const-ptr-is-null.rs | 1 - tests/ui/consts/const-ptr-is-null.stderr | 2 +- tests/ui/consts/ptr_is_null.rs | 1 - 9 files changed, 18 insertions(+), 13 deletions(-) diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs index 62115aef4a7..f12320cb851 100644 --- a/compiler/rustc_const_eval/src/const_eval/machine.rs +++ b/compiler/rustc_const_eval/src/const_eval/machine.rs @@ -263,6 +263,12 @@ impl<'tcx> CompileTimeInterpCx<'tcx> { } /// See documentation on the `ptr_guaranteed_cmp` intrinsic. + /// Returns `2` if the result is unknown. + /// Returns `1` if the pointers are guaranteed equal. + /// Returns `0` if the pointers are guaranteed inequal. + /// + /// Note that this intrinsic is exposed on stable for comparison with null. In other words, any + /// change to this function that affects comparison with null is insta-stable! fn guaranteed_cmp(&mut self, a: Scalar, b: Scalar) -> InterpResult<'tcx, u8> { interp_ok(match (a, b) { // Comparisons between integers are always known. diff --git a/library/core/src/intrinsics/mod.rs b/library/core/src/intrinsics/mod.rs index 72e34e5faf5..268af1c2965 100644 --- a/library/core/src/intrinsics/mod.rs +++ b/library/core/src/intrinsics/mod.rs @@ -3292,8 +3292,8 @@ pub const unsafe fn ptr_offset_from_unsigned(_ptr: *const T, _base: *const T) /// See documentation of `<*const T>::guaranteed_eq` for details. /// Returns `2` if the result is unknown. -/// Returns `1` if the pointers are guaranteed equal -/// Returns `0` if the pointers are guaranteed inequal +/// Returns `1` if the pointers are guaranteed equal. +/// Returns `0` if the pointers are guaranteed inequal. #[cfg_attr(bootstrap, rustc_const_unstable(feature = "const_raw_ptr_comparison", issue = "53020"))] #[rustc_intrinsic] #[rustc_nounwind] diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs index 6f7ea769420..1cacd1d2160 100644 --- a/library/core/src/lib.rs +++ b/library/core/src/lib.rs @@ -121,7 +121,6 @@ #![feature(const_heap)] #![feature(const_nonnull_new)] #![feature(const_pin_2)] -#![feature(const_ptr_is_null)] #![feature(const_ptr_sub_ptr)] #![feature(const_raw_ptr_comparison)] #![feature(const_size_of_val)] diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs index 2d7507e2d53..0dbe819acb1 100644 --- a/library/core/src/ptr/const_ptr.rs +++ b/library/core/src/ptr/const_ptr.rs @@ -29,16 +29,18 @@ impl *const T { /// assert!(!ptr.is_null()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] - #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")] + #[rustc_const_stable(feature = "const_ptr_is_null", since = "CURRENT_RUSTC_VERSION")] #[rustc_diagnostic_item = "ptr_const_is_null"] #[inline] + #[rustc_allow_const_fn_unstable(const_eval_select)] pub const fn is_null(self) -> bool { // Compare via a cast to a thin pointer, so fat pointers are only // considering their "data" part for null-ness. let ptr = self as *const u8; const_eval_select!( @capture { ptr: *const u8 } -> bool: - if const #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")] { + // This use of `const_raw_ptr_comparison` has been explicitly blessed by t-lang. + if const #[rustc_allow_const_fn_unstable(const_raw_ptr_comparison)] { match (ptr).guaranteed_eq(null_mut()) { Some(res) => res, // To remain maximally convervative, we stop execution when we don't @@ -280,7 +282,7 @@ impl *const T { /// } /// ``` #[stable(feature = "ptr_as_ref", since = "1.9.0")] - #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")] + #[rustc_const_stable(feature = "const_ptr_is_null", since = "CURRENT_RUSTC_VERSION")] #[inline] pub const unsafe fn as_ref<'a>(self) -> Option<&'a T> { // SAFETY: the caller must guarantee that `self` is valid diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs index 344ba46a50e..f0204bd0f77 100644 --- a/library/core/src/ptr/mut_ptr.rs +++ b/library/core/src/ptr/mut_ptr.rs @@ -29,7 +29,7 @@ impl *mut T { /// assert!(!ptr.is_null()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] - #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")] + #[rustc_const_stable(feature = "const_ptr_is_null", since = "CURRENT_RUSTC_VERSION")] #[rustc_diagnostic_item = "ptr_is_null"] #[inline] pub const fn is_null(self) -> bool { @@ -271,7 +271,7 @@ impl *mut T { /// } /// ``` #[stable(feature = "ptr_as_ref", since = "1.9.0")] - #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")] + #[rustc_const_stable(feature = "const_ptr_is_null", since = "CURRENT_RUSTC_VERSION")] #[inline] pub const unsafe fn as_ref<'a>(self) -> Option<&'a T> { // SAFETY: the caller must guarantee that `self` is valid for a @@ -619,7 +619,7 @@ impl *mut T { /// println!("{s:?}"); // It'll print: "[4, 2, 3]". /// ``` #[stable(feature = "ptr_as_ref", since = "1.9.0")] - #[rustc_const_unstable(feature = "const_ptr_is_null", issue = "74939")] + #[rustc_const_stable(feature = "const_ptr_is_null", since = "CURRENT_RUSTC_VERSION")] #[inline] pub const unsafe fn as_mut<'a>(self) -> Option<&'a mut T> { // SAFETY: the caller must guarantee that `self` is be valid for diff --git a/library/core/src/ub_checks.rs b/library/core/src/ub_checks.rs index 8fcbda141da..e21cd3fcec6 100644 --- a/library/core/src/ub_checks.rs +++ b/library/core/src/ub_checks.rs @@ -65,7 +65,7 @@ macro_rules! assert_unsafe_precondition { #[inline] #[rustc_nounwind] #[cfg_attr(bootstrap, rustc_const_unstable(feature = "const_ub_checks", issue = "none"))] - #[rustc_allow_const_fn_unstable(const_ptr_is_null, const_ub_checks)] // only for UB checks + #[rustc_allow_const_fn_unstable(const_ub_checks)] // only for UB checks const fn precondition_check($($name:$ty),*) { if !$e { ::core::panicking::panic_nounwind( diff --git a/tests/ui/consts/const-ptr-is-null.rs b/tests/ui/consts/const-ptr-is-null.rs index 82c293c0ad6..92cf87a9782 100644 --- a/tests/ui/consts/const-ptr-is-null.rs +++ b/tests/ui/consts/const-ptr-is-null.rs @@ -1,4 +1,3 @@ -#![feature(const_ptr_is_null)] use std::ptr; const IS_NULL: () = { diff --git a/tests/ui/consts/const-ptr-is-null.stderr b/tests/ui/consts/const-ptr-is-null.stderr index 5fd35142818..f71b3752772 100644 --- a/tests/ui/consts/const-ptr-is-null.stderr +++ b/tests/ui/consts/const-ptr-is-null.stderr @@ -8,7 +8,7 @@ note: inside `std::ptr::const_ptr::::is_null::compiletime` note: inside `std::ptr::const_ptr::::is_null` --> $SRC_DIR/core/src/ptr/const_ptr.rs:LL:COL note: inside `MAYBE_NULL` - --> $DIR/const-ptr-is-null.rs:17:14 + --> $DIR/const-ptr-is-null.rs:16:14 | LL | assert!(!ptr.wrapping_sub(512).is_null()); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/tests/ui/consts/ptr_is_null.rs b/tests/ui/consts/ptr_is_null.rs index bbf13802312..8b41f5718e8 100644 --- a/tests/ui/consts/ptr_is_null.rs +++ b/tests/ui/consts/ptr_is_null.rs @@ -1,7 +1,6 @@ //@ compile-flags: --crate-type=lib //@ check-pass -#![feature(const_ptr_is_null)] #![allow(useless_ptr_null_checks)] const FOO: &usize = &42;