From 6c3e16aca95a82fa6cd5bf09f0e671b488dfc91d Mon Sep 17 00:00:00 2001
From: Ada Alakbarova <ada.alakbarova@proton.me>
Date: Sun, 9 Nov 2025 20:49:29 +0100
Subject: [PATCH] perf(time_subtraction): avoid querying type/diag name of lhs
 twice

---
 clippy_lints/src/time_subtraction.rs | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/clippy_lints/src/time_subtraction.rs b/clippy_lints/src/time_subtraction.rs
index dbd4ec77fd5f..15c24c5764f2 100644
--- a/clippy_lints/src/time_subtraction.rs
+++ b/clippy_lints/src/time_subtraction.rs
@@ -119,7 +119,7 @@ impl LateLintPass<'_> for UncheckedTimeSubtraction {
                         );
                     } else {
                         // instant - duration
-                        print_unchecked_duration_subtraction_sugg(cx, lhs, rhs, expr);
+                        print_unchecked_duration_subtraction_sugg(cx, lhs, true, rhs, expr);
                     }
                 }
             } else if lhs_ty.is_diag_item(cx, sym::Duration)
@@ -137,7 +137,7 @@ impl LateLintPass<'_> for UncheckedTimeSubtraction {
                     );
                 } else {
                     // duration - duration
-                    print_unchecked_duration_subtraction_sugg(cx, lhs, rhs, expr);
+                    print_unchecked_duration_subtraction_sugg(cx, lhs, false, rhs, expr);
                 }
             }
         }
@@ -188,13 +188,11 @@ fn print_manual_instant_elapsed_sugg(cx: &LateContext<'_>, expr: &Expr<'_>, sugg
 fn print_unchecked_duration_subtraction_sugg(
     cx: &LateContext<'_>,
     left_expr: &Expr<'_>,
+    left_is_instant: bool,
     right_expr: &Expr<'_>,
     expr: &Expr<'_>,
 ) {
-    let typeck = cx.typeck_results();
-    let left_ty = typeck.expr_ty(left_expr);
-
-    let lint_msg = if left_ty.is_diag_item(cx, sym::Instant) {
+    let lint_msg = if left_is_instant {
         "unchecked subtraction of a 'Duration' from an 'Instant'"
     } else {
         "unchecked subtraction between 'Duration' values"