Merge pull request matplotlib#19833 from meeseeksmachine/auto-backport-of-pr-19811-on-v3.4.x

Backport PR matplotlib#19811 on branch v3.4.x (Fix Inkscape cleanup at exit on Windows.)

Author: QuLogic

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 = {