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Clause::kind use unreachable_unchecked #163639

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Clause::kind use unreachable_unchecked #163639

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3 changes: 2 additions & 1 deletion compiler/rustc_middle/src/ty/predicate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -173,7 +173,8 @@ impl<'tcx> Clause<'tcx> {
pub fn kind(self) -> ty::Binder<'tcx, ClauseKind<'tcx>> {
self.0.internee.map_bound(|kind| match kind {
PredicateKind::Clause(clause) => clause,
_ => unreachable!(),
// SAFETY: This function is incredibly hot. Let's make it optimize better.
_ => unsafe { std::hint::unreachable_unchecked() },
Comment on lines +176 to +177

@lcnr lcnr Oct 2, 2026 •
edited by rustbot
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I don't understand safety comments apparently. This is not a safety comment

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@lqd lqd Oct 2, 2026

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// HOTNESS: This function is incredibly hot.

@lcnr lcnr Oct 2, 2026

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Now the big problem, is that it's non-trivial to actually make this safe. THis field is public and the best commit is "while pub(super), nobody constructs a clause from something that's not a PredicateKind::Clause"

})
}

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