Tracking Issue for `likely_unlikely` and `cold_path`

[tgross35]

Feature gate: #![feature(likely_unlikely)], #![feature(cold_path)]

This is a tracking issue for core::hint::{likely, unlikely, cold_path}.

Please also see the meta discussion at #26179.

Public API

// core::hint

// Usable via `#![feature(cold_path)]`
pub const fn cold_path();

// Usable via `#![feature(likely_unlikely)]`
pub const fn likely(b: bool) -> bool;
pub const fn unlikely(b: bool) -> bool;

Steps / History

• Intrinsic implementation: Likely unlikely fix #120370
• Reexport in std::hint: Reexport likely/unlikely in std::hint #133695
• Behavior improvements: improve cold_path() #133852
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• Do we want all of these functions, or only a subset?

Footnotes

1. https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html ↩

[safinaskar]

I think stabilizing cold_path is blocked on #133852