From d3f2879241b90a12182d1d78a04fc91088c584e0 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 9 Jan 2025 17:09:48 -0800
Subject: [PATCH 1/3] Add regression test for chained comparisons with bailout

    thread 'test_fixup' panicked at tests/test_expr.rs:843:25:
    failed to parse `x > .. > x`: comparison operators cannot be chained
    note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
---
 tests/test_expr.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/test_expr.rs b/tests/test_expr.rs
index cfbf16236..226c044db 100644
--- a/tests/test_expr.rs
+++ b/tests/test_expr.rs
@@ -799,6 +799,7 @@ fn test_fixup() {
         quote! { (1 + 1).abs() },
         quote! { (lo..hi)[..] },
         quote! { (a..b)..(c..d) },
+        quote! { (x > ..) > x },
         quote! { (&mut fut).await },
         quote! { &mut (x as i32) },
         quote! { -(x as i32) },

From fd198d9b0c9cd850666618156758f78df45d73e0 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 9 Jan 2025 17:07:49 -0800
Subject: [PATCH 2/3] Generalize Expr::Range bailout to any operator that can
 begin expr

---
 src/fixup.rs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/fixup.rs b/src/fixup.rs
index 9414d8384..2576ec365 100644
--- a/src/fixup.rs
+++ b/src/fixup.rs
@@ -639,10 +639,13 @@ fn scan_right(
                     Scan::Fail
                 }
             }
-            None => match fixup.next_operator {
-                Precedence::Range => Scan::Consume,
-                _ => Scan::Fail,
-            },
+            None => {
+                if fixup.next_operator_can_begin_expr {
+                    Scan::Consume
+                } else {
+                    Scan::Fail
+                }
+            }
         },
         Expr::Break(e) => match &e.expr {
             Some(value) => {

From 49443622bd2ff2986554ca58d7ee13436d784c22 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 9 Jan 2025 17:11:12 -0800
Subject: [PATCH 3/3] Fix parenthesization of chained comparisons containing
 bailout

---
 src/fixup.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/fixup.rs b/src/fixup.rs
index 2576ec365..e49f81131 100644
--- a/src/fixup.rs
+++ b/src/fixup.rs
@@ -547,6 +547,9 @@ fn scan_right(
                 return Scan::Consume;
             }
             let binop_prec = Precedence::of_binop(&e.op);
+            if binop_prec == Precedence::Compare && fixup.next_operator == Precedence::Compare {
+                return Scan::Consume;
+            }
             let right_fixup = fixup.rightmost_subexpression_fixup(false, false, binop_prec);
             let scan = scan_right(
                 &e.right,