@@ -578,18 +578,18 @@ pub fn collect_trait_impl_trait_tys<'tcx>(
578578 // region substs that are synthesized during AST lowering. These are substs
579579 // that are appended to the parent substs (trait and trait method). However,
580580 // we're trying to infer the unsubstituted type value of the RPITIT inside
581- // the *impl*, so we can later use the impl's method substitutions to normalize
582- // an RPITIT to a concrete type.
581+ // the *impl*, so we can later use the impl's method substs to normalize
582+ // an RPITIT to a concrete type (`confirm_impl_trait_in_trait_candidate`) .
583583 //
584584 // Due to the design of RPITITs, during AST lowering, we have no idea that
585- // an impl method is satisfying a trait method with RPITITs in it. Therefore,
586- // we don't have a list ofearly -bound region substs for the RPITIT in the impl.
585+ // an impl method corresponds to a trait method with RPITITs in it. Therefore,
586+ // we don't have a list of early -bound region substs for the RPITIT in the impl.
587587 // Since early region parameters are index-based, we can't just rebase these
588- // (trait method) early-bound region substs onto the impl, since region
589- // parameters are index-based, and there's no guarantee that the indices from
590- // the trait substs and impl substs line up -- so we subtract the number of
591- // trait substs and add the number of impl substs to *renumber* these early-
592- // bound regions to their corresponding indices in the impl's substitutions list.
588+ // (trait method) early-bound region substs onto the impl, and there's no
589+ // guarantee that the indices from the trait substs and impl substs line up.
590+ // So to fix this, we subtract the number of trait substs and add the number of
591+ // impl substs to *renumber* these early-bound regions to their corresponding
592+ // indices in the impl's substitutions list.
593593 //
594594 // Also, we only need to account for a difference in trait and impl substs,
595595 // since we previously enforce that the trait method and impl method have the
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