From 6e6fcf4786f75a93584a84cb663b956b1cbbfadc Mon Sep 17 00:00:00 2001
From: Thomas A Caswell <tcaswell@gmail.com>
Date: Wed, 31 Mar 2021 00:03:21 -0400
Subject: [PATCH] Backport PR #19811: Fix Inkscape cleanup at exit on Windows.

---
 lib/matplotlib/testing/compare.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/matplotlib/testing/compare.py b/lib/matplotlib/testing/compare.py
index fb2e55880cde..afb7edb8c828 100644
--- a/lib/matplotlib/testing/compare.py
+++ b/lib/matplotlib/testing/compare.py
@@ -13,6 +13,7 @@
 import subprocess
 import sys
 from tempfile import TemporaryDirectory, TemporaryFile
+import weakref
 
 import numpy as np
 from PIL import Image
@@ -170,6 +171,9 @@ def __call__(self, orig, dest):
         terminator = b"\n>" if old_inkscape else b"> "
         if not hasattr(self, "_tmpdir"):
             self._tmpdir = TemporaryDirectory()
+            # On Windows, we must make sure that self._proc has terminated
+            # (which __del__ does) before clearing _tmpdir.
+            weakref.finalize(self._tmpdir, self.__del__)
         if (not self._proc  # First run.
                 or self._proc.poll() is not None):  # Inkscape terminated.
             env = {