Add explanation for skip_binder in relate

rust-lang · Dec 14, 2020 · 01c2520 · 01c2520
1 parent ed80815
commit 01c2520
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs
@@ -616,6 +616,7 @@ impl<'tcx> Relate<'tcx> for &'tcx ty::List<ty::Binder<ty::ExistentialPredicate<'
  // in `a`.
  let mut a_v: Vec<_> = a.into_iter().collect();
  let mut b_v: Vec<_> = b.into_iter().collect();
+ // `skip_binder` here is okay because `stable_cmp` doesn't look at binders
  a_v.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder()));
  a_v.dedup();
  b_v.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder()));