From f74ca88384cbce7e318a7a0142a9ac3eda6b8641 Mon Sep 17 00:00:00 2001
From: Nilstrieb <48135649+Nilstrieb@users.noreply.github.com>
Date: Sat, 21 Jan 2023 20:12:40 +0100
Subject: [PATCH] Use a type-alias-impl-trait in `ObligationForest`

---
 compiler/rustc_data_structures/src/obligation_forest/mod.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/compiler/rustc_data_structures/src/obligation_forest/mod.rs b/compiler/rustc_data_structures/src/obligation_forest/mod.rs
index 10e673cd929..dda422c6dd0 100644
--- a/compiler/rustc_data_structures/src/obligation_forest/mod.rs
+++ b/compiler/rustc_data_structures/src/obligation_forest/mod.rs
@@ -139,8 +139,7 @@ pub enum ProcessResult<O, E> {
 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
 struct ObligationTreeId(usize);
 
-type ObligationTreeIdGenerator =
-    std::iter::Map<std::ops::RangeFrom<usize>, fn(usize) -> ObligationTreeId>;
+type ObligationTreeIdGenerator = impl Iterator<Item = ObligationTreeId>;
 
 pub struct ObligationForest<O: ForestObligation> {
     /// The list of obligations. In between calls to [Self::process_obligations],