From 0ba5e7416ffca2de7d328d0bcbd0321ab790edb3 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 22 Nov 2022 18:35:41 +0000
Subject: [PATCH] Add size hints to early binder iterator adapters

---
 compiler/rustc_middle/src/ty/subst.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/compiler/rustc_middle/src/ty/subst.rs b/compiler/rustc_middle/src/ty/subst.rs
index c1cf7896db5..d8c1c63d7a3 100644
--- a/compiler/rustc_middle/src/ty/subst.rs
+++ b/compiler/rustc_middle/src/ty/subst.rs
@@ -589,6 +589,10 @@ impl<'tcx, I: IntoIterator> Iterator for SubstIter<'_, 'tcx, I>
     fn next(&mut self) -> Option<Self::Item> {
         Some(EarlyBinder(self.it.next()?).subst(self.tcx, self.substs))
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.it.size_hint()
+    }
 }
 
 impl<'tcx, I: IntoIterator> DoubleEndedIterator for SubstIter<'_, 'tcx, I>
@@ -631,6 +635,10 @@ impl<'tcx, I: IntoIterator> Iterator for SubstIterCopied<'_, 'tcx, I>
     fn next(&mut self) -> Option<Self::Item> {
         Some(EarlyBinder(*self.it.next()?).subst(self.tcx, self.substs))
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.it.size_hint()
+    }
 }
 
 impl<'tcx, I: IntoIterator> DoubleEndedIterator for SubstIterCopied<'_, 'tcx, I>
@@ -660,6 +668,10 @@ impl<T: Iterator> Iterator for EarlyBinderIter<T> {
     fn next(&mut self) -> Option<Self::Item> {
         self.t.next().map(|i| EarlyBinder(i))
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.t.size_hint()
+    }
 }
 
 impl<'tcx, T: TypeFoldable<'tcx>> ty::EarlyBinder<T> {