From 605a29068ed04ff529828ca9d77b670007eb39a5 Mon Sep 17 00:00:00 2001
From: camc314 <18101008+camc314@users.noreply.github.com>
Date: Mon, 22 Dec 2025 13:50:02 +0000
Subject: [PATCH] perf(semantic): use swap_remove instead of into_iter().next()
 in into_root (#17183)

---
 crates/oxc_semantic/src/unresolved_stack.rs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/crates/oxc_semantic/src/unresolved_stack.rs b/crates/oxc_semantic/src/unresolved_stack.rs
index d6c160cf1698a..34bd6fb579abd 100644
--- a/crates/oxc_semantic/src/unresolved_stack.rs
+++ b/crates/oxc_semantic/src/unresolved_stack.rs
@@ -105,10 +105,12 @@ impl<'a> UnresolvedReferencesStack<'a> {
     }
 
     #[inline]
-    pub(crate) fn into_root(self) -> TempUnresolvedReferences<'a> {
+    pub(crate) fn into_root(mut self) -> TempUnresolvedReferences<'a> {
         // SAFETY: Stack starts with a non-zero size and never shrinks.
-        // This assertion removes bounds check in `.next()`.
+        // This assertion removes bounds check in `swap_remove`.
         unsafe { assert_unchecked!(!self.stack.is_empty()) };
-        self.stack.into_iter().next().unwrap()
+        // Use `swap_remove(0)` instead of `into_iter().next().unwrap()` to avoid
+        // creating an iterator just to get the first element.
+        self.stack.swap_remove(0)
     }
 }