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Remove unnecessary trait predicate eq function

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This commit is contained in:
Michael Goulet 2025-08-11 01:45:13 +00:00
parent b5cee774ac
commit 50323736ad
1 changed files with 1 additions and 33 deletions
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34
compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs
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@ -390,45 +390,13 @@ fn check_predicates<'tcx>(
let mut res = Ok(());
for (clause, span) in impl1_predicates {
if !impl2_predicates.iter().any(|pred2| trait_predicates_eq(clause.as_predicate(), *pred2))
{
if !impl2_predicates.iter().any(|&pred2| clause.as_predicate() == pred2) {
res = res.and(check_specialization_on(tcx, clause, span))
}
}
res
}
/// Checks if some predicate on the specializing impl (`predicate1`) is the same
/// as some predicate on the base impl (`predicate2`).
///
/// This basically just checks syntactic equivalence, but is a little more
/// forgiving since we want to equate `T: Tr` with `T: [const] Tr` so this can work:
///
/// ```ignore (illustrative)
/// #[rustc_specialization_trait]
/// trait Specialize { }
///
/// impl<T: Bound> Tr for T { }
/// impl<T: [const] Bound + Specialize> const Tr for T { }
/// ```
///
/// However, we *don't* want to allow the reverse, i.e., when the bound on the
/// specializing impl is not as const as the bound on the base impl:
///
/// ```ignore (illustrative)
/// impl<T: [const] Bound> const Tr for T { }
/// impl<T: Bound + Specialize> const Tr for T { } // should be T: [const] Bound
/// ```
///
/// So we make that check in this function and try to raise a helpful error message.
fn trait_predicates_eq<'tcx>(
predicate1: ty::Predicate<'tcx>,
predicate2: ty::Predicate<'tcx>,
) -> bool {
// FIXME(const_trait_impl)
predicate1 == predicate2
}
#[instrument(level = "debug", skip(tcx))]
fn check_specialization_on<'tcx>(
tcx: TyCtxt<'tcx>,