From 3cc39b16751c20e1578c788cca82f3c6730ea0db Mon Sep 17 00:00:00 2001
From: AlexWaygood <alex.waygood@gmail.com>
Date: Sat, 25 Nov 2023 20:29:57 +0000
Subject: [PATCH 1/3] gh-112405: Optimise `pathlib.Path.relative_to`

---
 Lib/pathlib.py                                                 | 3 ++-
 .../Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst     | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst

diff --git a/Lib/pathlib.py b/Lib/pathlib.py
index 0e01099d490a7e..81f75cd47ed087 100644
--- a/Lib/pathlib.py
+++ b/Lib/pathlib.py
@@ -14,6 +14,7 @@
 import warnings
 from _collections_abc import Sequence
 from errno import ENOENT, ENOTDIR, EBADF, ELOOP, EINVAL
+from itertools import chain
 from stat import S_ISDIR, S_ISLNK, S_ISREG, S_ISSOCK, S_ISBLK, S_ISCHR, S_ISFIFO
 
 try:
@@ -445,7 +446,7 @@ def relative_to(self, other, /, *_deprecated, walk_up=False):
             other = self.with_segments(other, *_deprecated)
         elif not isinstance(other, PurePath):
             other = self.with_segments(other)
-        for step, path in enumerate([other] + list(other.parents)):
+        for step, path in enumerate(chain([other], other.parents)):
             if path == self or path in self.parents:
                 break
             elif not walk_up:
diff --git a/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst b/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst
new file mode 100644
index 00000000000000..acdd957d599bc5
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst
@@ -0,0 +1 @@
+Optimise :meth:`pathlib.Path.relative_to`. Patch by Alex Waygood.

From ba3bf0c2e9276ba6088a8df088dcfc550a25e633 Mon Sep 17 00:00:00 2001
From: Alex Waygood <Alex.Waygood@Gmail.com>
Date: Sun, 26 Nov 2023 09:51:04 +0000
Subject: [PATCH 2/3] Concede to the Yanks

Co-authored-by: Itamar Oren <itamarost@gmail.com>
---
 .../next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst b/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst
index acdd957d599bc5..9a6bd6ff5911c0 100644
--- a/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst
+++ b/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst
@@ -1 +1 @@
-Optimise :meth:`pathlib.Path.relative_to`. Patch by Alex Waygood.
+Optimize :meth:`pathlib.Path.relative_to`. Patch by Alex Waygood.

From c57d5679494800912d66b13121341880b43c310b Mon Sep 17 00:00:00 2001
From: Alex Waygood <Alex.Waygood@Gmail.com>
Date: Sun, 26 Nov 2023 15:39:31 +0000
Subject: [PATCH 3/3] Update
 Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst

Co-authored-by: Barney Gale <barney.gale@gmail.com>
---
 .../next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst b/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst
index 9a6bd6ff5911c0..f6f1bee2a0c38f 100644
--- a/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst
+++ b/Misc/NEWS.d/next/Library/2023-11-25-20-29-28.gh-issue-112405.cOtzxC.rst
@@ -1 +1 @@
-Optimize :meth:`pathlib.Path.relative_to`. Patch by Alex Waygood.
+Optimize :meth:`pathlib.PurePath.relative_to`. Patch by Alex Waygood.