From 113d02adf1d8a99a7400851d70253c3dd6c19c16 Mon Sep 17 00:00:00 2001
From: Thomas A Caswell <tcaswell@gmail.com>
Date: Tue, 31 Dec 2024 15:08:31 -0500
Subject: [PATCH 1/3] MNT: use copy.deepcopy to implement deepcopy method

We provide deepcopy and copy methods as a shortcut for users to avoid having to
import the copy module and call the required function.  Directly calling
`__deepcopy__` side-steps all of the memoization machinery and may lead to
incorrect results.
---
 lib/matplotlib/path.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lib/matplotlib/path.py b/lib/matplotlib/path.py
index a021706fb1e5..9c3f50320636 100644
--- a/lib/matplotlib/path.py
+++ b/lib/matplotlib/path.py
@@ -285,7 +285,12 @@ def __deepcopy__(self, memo=None):
         p._readonly = False
         return p
 
-    deepcopy = __deepcopy__
+    def deepcopy(self, memo=None):
+        """
+        Return a shallow copy of the `Path`, which will share the
+        vertices and codes with the source `Path`.
+        """
+        return copy.deepcopy(self, memo=memo)
 
     @classmethod
     def make_compound_path_from_polys(cls, XY):

From 42874f95233eefcae0b5564ef752898d31dd37ea Mon Sep 17 00:00:00 2001
From: Thomas A Caswell <tcaswell@gmail.com>
Date: Tue, 31 Dec 2024 15:16:13 -0500
Subject: [PATCH 2/3] FIX: account for changes to cpython with copy/deepcopy to
 super()

See https://github.com/python/cpython/issues/126817 for upstream discussion.

This works around the change by using (private) methods from the copy module to
re-implement the path though copy/deepcopy that we would like to use but avoid
the special-casing for `super()` objects that is breaking us.

We could vendor the current versions of `_keep_alive` (weakref work to manage
lifecycles) and `_reconstruct` (where the recursion happens) to superficially
avoid using private functions from CPython.  However, if these functions do
change significantly I worry that our copies would not inter-operate anyway.

Closes #29157
---
 lib/matplotlib/path.py       | 13 ++++++++++++-
 lib/matplotlib/transforms.py |  8 +++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/lib/matplotlib/path.py b/lib/matplotlib/path.py
index 9c3f50320636..1660d090e318 100644
--- a/lib/matplotlib/path.py
+++ b/lib/matplotlib/path.py
@@ -11,6 +11,7 @@
 
 import copy
 from functools import lru_cache
+import sys
 from weakref import WeakValueDictionary
 
 import numpy as np
@@ -281,7 +282,17 @@ def __deepcopy__(self, memo=None):
         readonly, even if the source `Path` is.
         """
         # Deepcopying arrays (vertices, codes) strips the writeable=False flag.
-        p = copy.deepcopy(super(), memo)
+        if sys.version_info >= (3, 14):
+            from copy import _reconstruct, _keep_alive
+            rv = super().__reduce_ex__(4)
+            assert memo is not None
+            p = _reconstruct(self, memo, *rv)
+            if memo is not None:
+                memo[id(self)] = p
+                _keep_alive(self, memo)
+
+        else:
+            p = copy.deepcopy(super(), memo)
         p._readonly = False
         return p
 
diff --git a/lib/matplotlib/transforms.py b/lib/matplotlib/transforms.py
index 2cca56f04457..f874184affae 100644
--- a/lib/matplotlib/transforms.py
+++ b/lib/matplotlib/transforms.py
@@ -38,6 +38,7 @@
 import copy
 import functools
 import itertools
+import sys
 import textwrap
 import weakref
 import math
@@ -140,7 +141,12 @@ def __setstate__(self, data_dict):
             for k, v in self._parents.items() if v is not None}
 
     def __copy__(self):
-        other = copy.copy(super())
+        if sys.version_info >= (3, 14):
+            from copy import _reconstruct
+            rv = super().__reduce_ex__(4)
+            other = _reconstruct(self, None, *rv)
+        else:
+            other = copy.copy(super())
         # If `c = a + b; a1 = copy(a)`, then modifications to `a1` do not
         # propagate back to `c`, i.e. we need to clear the parents of `a1`.
         other._parents = {}

From 717ea248bd1cedda6e18336afa7879f4372e8324 Mon Sep 17 00:00:00 2001
From: Thomas A Caswell <tcaswell@gmail.com>
Date: Thu, 9 Jan 2025 13:41:32 -0500
Subject: [PATCH 3/3] DOC: correct deepcopy docstring

---
 lib/matplotlib/path.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/matplotlib/path.py b/lib/matplotlib/path.py
index 1660d090e318..e4a7403ceecb 100644
--- a/lib/matplotlib/path.py
+++ b/lib/matplotlib/path.py
@@ -298,7 +298,7 @@ def __deepcopy__(self, memo=None):
 
     def deepcopy(self, memo=None):
         """
-        Return a shallow copy of the `Path`, which will share the
+        Return a deep copy of the `Path`, with copies of the
         vertices and codes with the source `Path`.
         """
         return copy.deepcopy(self, memo=memo)