From a7f3c4e6086c70f1c617bae6c157d5dc5636670f Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Thu, 28 Sep 2023 22:39:53 +0000
Subject: [PATCH] Don't resolve basic block data in `Postorder`

The only usage immediately throws out the data, so.
---
 compiler/rustc_middle/src/mir/basic_blocks.rs |  3 +--
 compiler/rustc_middle/src/mir/traversal.rs    | 10 +++++-----
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/compiler/rustc_middle/src/mir/basic_blocks.rs b/compiler/rustc_middle/src/mir/basic_blocks.rs
index cd770c395e4..c0f02c64bbf 100644
--- a/compiler/rustc_middle/src/mir/basic_blocks.rs
+++ b/compiler/rustc_middle/src/mir/basic_blocks.rs
@@ -66,8 +66,7 @@ pub fn predecessors(&self) -> &Predecessors {
     #[inline]
     pub fn reverse_postorder(&self) -> &[BasicBlock] {
         self.cache.reverse_postorder.get_or_init(|| {
-            let mut rpo: Vec<_> =
-                Postorder::new(&self.basic_blocks, START_BLOCK).map(|(bb, _)| bb).collect();
+            let mut rpo: Vec<_> = Postorder::new(&self.basic_blocks, START_BLOCK).collect();
             rpo.reverse();
             rpo
         })
diff --git a/compiler/rustc_middle/src/mir/traversal.rs b/compiler/rustc_middle/src/mir/traversal.rs
index 07baaa6f90c..a89dbf991f0 100644
--- a/compiler/rustc_middle/src/mir/traversal.rs
+++ b/compiler/rustc_middle/src/mir/traversal.rs
@@ -188,14 +188,14 @@ fn traverse_successor(&mut self) {
     }
 }
 
-impl<'a, 'tcx> Iterator for Postorder<'a, 'tcx> {
-    type Item = (BasicBlock, &'a BasicBlockData<'tcx>);
+impl<'tcx> Iterator for Postorder<'_, 'tcx> {
+    type Item = BasicBlock;
 
-    fn next(&mut self) -> Option<(BasicBlock, &'a BasicBlockData<'tcx>)> {
+    fn next(&mut self) -> Option<BasicBlock> {
         let (bb, _) = self.visit_stack.pop()?;
         self.traverse_successor();
-        
-        Some((bb, &self.basic_blocks[bb]))
+
+        Some(bb)
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {