From 0cc5284deb694b1e7049a15fe47c1fe8f3e1e154 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Robert?= <cr52@protonmail.com>
Date: Sat, 4 Mar 2023 13:21:19 +0100
Subject: [PATCH] ENH: switch mpl_toolkits to implicit namespace package (PEP
 420)

---
 doc/users/next_whats_new/mpl_toolkit_pep420.rst | 6 ++++++
 lib/mpl_toolkits/__init__.py                    | 4 ----
 setup.py                                        | 8 +++++---
 3 files changed, 11 insertions(+), 7 deletions(-)
 create mode 100644 doc/users/next_whats_new/mpl_toolkit_pep420.rst
 delete mode 100644 lib/mpl_toolkits/__init__.py

diff --git a/doc/users/next_whats_new/mpl_toolkit_pep420.rst b/doc/users/next_whats_new/mpl_toolkit_pep420.rst
new file mode 100644
index 000000000000..3d7daf48c1d7
--- /dev/null
+++ b/doc/users/next_whats_new/mpl_toolkit_pep420.rst
@@ -0,0 +1,6 @@
+``matplotlib.mpl_toolkits`` is now an implicit namespace package
+----------------------------------------------------------------
+
+Following the deprecation of ``pkg_resources.declare_namespace`` in ``setuptools`` 67.3.0,
+``matplotlib.mpl_toolkits`` is now implemented as an implicit namespace, following
+`PEP 420 <https://peps.python.org/pep-0420/>`_.
diff --git a/lib/mpl_toolkits/__init__.py b/lib/mpl_toolkits/__init__.py
deleted file mode 100644
index 02de4115d7f8..000000000000
--- a/lib/mpl_toolkits/__init__.py
+++ /dev/null
@@ -1,4 +0,0 @@
-try:
-    __import__('pkg_resources').declare_namespace(__name__)
-except ImportError:
-    pass  # must not have setuptools
diff --git a/setup.py b/setup.py
index 6d96e6b86c2d..6d16fe3fac6b 100644
--- a/setup.py
+++ b/setup.py
@@ -29,7 +29,7 @@
 import shutil
 import subprocess
 
-from setuptools import setup, find_packages, Distribution, Extension
+from setuptools import setup, find_namespace_packages, Distribution, Extension
 import setuptools.command.build_ext
 import setuptools.command.build_py
 import setuptools.command.sdist
@@ -301,8 +301,10 @@ def make_release_tree(self, base_dir, files):
     ],
 
     package_dir={"": "lib"},
-    packages=find_packages("lib"),
-    namespace_packages=["mpl_toolkits"],
+    packages=find_namespace_packages(
+        where="lib",
+        exclude=["*baseline_images*", "*tinypages*", "*mpl-data*", "*web_backend*"],
+    ),
     py_modules=["pylab"],
     # Dummy extension to trigger build_ext, which will swap it out with
     # real extensions that can depend on numpy for the build.