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| author | Trevor Gross <tmgross@umich.edu> | 2025-01-12 20:18:45 +0000 |
|---|---|---|
| committer | Trevor Gross <tmgross@umich.edu> | 2025-01-27 07:54:58 +0000 |
| commit | 395f0c9ecd1c3f238707c7a0788e4b1d84e2e70e (patch) | |
| tree | 4517283898ca344c5187e59b349a1b356fa7806b | |
| parent | 633a3fe36dd9a5196054dc3a61adbd3c61854dcf (diff) | |
| download | rust-395f0c9ecd1c3f238707c7a0788e4b1d84e2e70e.tar.gz rust-395f0c9ecd1c3f238707c7a0788e4b1d84e2e70e.zip | |
Stabilize `const_black_box`
This has been unstably const since [1], but a tracking issue was never created. Per discussion on Zulip [2], there should not be any blockers to making this const-stable. The function does not provide any functionality at compile time but does allow code reuse between const- and non-const functions, so stabilize it here. [1]: https://github.com/rust-lang/rust/pull/92226 [2]: https://rust-lang.zulipchat.com/#narrow/channel/146212-t-compiler.2Fconst-eval/topic/const_black_box
| -rw-r--r-- | compiler/rustc_codegen_gcc/tests/run/int.rs | 2 | ||||
| -rw-r--r-- | library/core/src/hint.rs | 4 | ||||
| -rw-r--r-- | library/core/src/intrinsics/mod.rs | 1 | ||||
| -rw-r--r-- | library/coretests/tests/lib.rs | 1 |
4 files changed, 4 insertions, 4 deletions
diff --git a/compiler/rustc_codegen_gcc/tests/run/int.rs b/compiler/rustc_codegen_gcc/tests/run/int.rs index bfe73c38435..58a26801b67 100644 --- a/compiler/rustc_codegen_gcc/tests/run/int.rs +++ b/compiler/rustc_codegen_gcc/tests/run/int.rs @@ -3,8 +3,6 @@ // Run-time: // status: 0 -#![feature(const_black_box)] - /* * Code */ diff --git a/library/core/src/hint.rs b/library/core/src/hint.rs index 80f6e32b6b2..e5c1a64c12e 100644 --- a/library/core/src/hint.rs +++ b/library/core/src/hint.rs @@ -468,9 +468,11 @@ pub fn spin_loop() { /// // No assumptions can be made about either operand, so the multiplication is not optimized out. /// let y = black_box(5) * black_box(10); /// ``` +/// +/// During constant evaluation, `black_box` is treated as a no-op. #[inline] #[stable(feature = "bench_black_box", since = "1.66.0")] -#[rustc_const_unstable(feature = "const_black_box", issue = "none")] +#[rustc_const_stable(feature = "const_black_box", since = "CURRENT_RUSTC_VERSION")] pub const fn black_box<T>(dummy: T) -> T { crate::intrinsics::black_box(dummy) } diff --git a/library/core/src/intrinsics/mod.rs b/library/core/src/intrinsics/mod.rs index 41b2ffad668..c0d435f99c0 100644 --- a/library/core/src/intrinsics/mod.rs +++ b/library/core/src/intrinsics/mod.rs @@ -3725,6 +3725,7 @@ pub const unsafe fn compare_bytes(_left: *const u8, _right: *const u8, _bytes: u #[rustc_nounwind] #[rustc_intrinsic] #[rustc_intrinsic_must_be_overridden] +#[rustc_intrinsic_const_stable_indirect] pub const fn black_box<T>(_dummy: T) -> T { unimplemented!() } diff --git a/library/coretests/tests/lib.rs b/library/coretests/tests/lib.rs index 0607d508a48..7fe72862608 100644 --- a/library/coretests/tests/lib.rs +++ b/library/coretests/tests/lib.rs @@ -14,7 +14,6 @@ #![feature(bstr)] #![feature(cell_update)] #![feature(clone_to_uninit)] -#![feature(const_black_box)] #![feature(const_eval_select)] #![feature(const_swap_nonoverlapping)] #![feature(const_trait_impl)] |