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black_box hint - Adjust for improved readability

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pat-nel87 2023-03-07 18:32:58 -05:00 committed by GitHub
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library/core/src/hint.rs
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@ -217,17 +217,14 @@ pub fn spin_loop() {
/// Note however, that `black_box` is only (and can only be) provided on a "best-effort" basis. The
/// extent to which it can block optimisations may vary depending upon the platform and code-gen
/// backend used. Programs cannot rely on `black_box` for *correctness*, beyond it behaving as the
/// identity function.
/// identity function. As such, it **must not be relied upon to control critical program behavior.**
/// This _immediately_ precludes any direct use of this function for cryptographic or security
/// purposes.
///
/// [`std::convert::identity`]: crate::convert::identity
///
/// # When is this useful?
///
/// First and foremost: `black_box` does _not_ guarantee any exact behavior beyond behaving as the identity function
/// and, in some cases, does nothing at all. As such, it **must not be relied upon to control critical program behavior.**
/// This _immediately_ precludes any direct use of this function for cryptographic or security
/// purposes.
///
/// While not suitable in those mission-critical cases, `black_box`'s functionality can generally be
/// relied upon for benchmarking, and should be used there. It will try to ensure that the
/// compiler doesn't optimize away part of the intended test code based on context. For