diff -up pip-19.3.1/news/7872.bugfix.pip7873 pip-19.3.1/news/7872.bugfix

--- pip-19.3.1/news/7872.bugfix.pip7873	2022-05-24 08:34:03.285054864 -0600

+++ pip-19.3.1/news/7872.bugfix	2022-05-24 08:34:03.285054864 -0600

@@ -0,0 +1 @@

+Prevent an infinite recursion with ``pip wheel`` when ``$TMPDIR`` is within the source directory.

diff -up pip-19.3.1/src/pip/_internal/download.py.pip7873 pip-19.3.1/src/pip/_internal/download.py

--- pip-19.3.1/src/pip/_internal/download.py.pip7873	2019-10-17 13:32:34.000000000 -0600

+++ pip-19.3.1/src/pip/_internal/download.py	2022-05-24 08:35:17.013833331 -0600

@@ -350,12 +350,24 @@ def _copy2_ignoring_special_files(src, d

 def _copy_source_tree(source, target):

     # type: (str, str) -> None

+    target_abspath = os.path.abspath(target)

+    target_basename = os.path.basename(target_abspath)

+    target_dirname = os.path.dirname(target_abspath)

+

     def ignore(d, names):

-        # Pulling in those directories can potentially be very slow,

-        # exclude the following directories if they appear in the top

-        # level dir (and only it).

-        # See discussion at https://github.com/pypa/pip/pull/6770

-        return ['.tox', '.nox'] if d == source else []

+        skipped = []  # type: List[str]

+        if d == source:

+            # Pulling in those directories can potentially be very slow,

+            # exclude the following directories if they appear in the top

+            # level dir (and only it).

+            # See discussion at https://github.com/pypa/pip/pull/6770

+            skipped += ['.tox', '.nox']

+        if os.path.abspath(d) == target_dirname:

+            # Prevent an infinite recursion if the target is in source.

+            # This can happen when TMPDIR is set to ${PWD}/...

+            # and we copy PWD to TMPDIR.

+            skipped += [target_basename]

+        return skipped

     kwargs = dict(ignore=ignore, symlinks=True)  # type: CopytreeKwargs

diff -up pip-19.3.1/src/pip/_internal/operations/prepare.py.pip7873 pip-19.3.1/src/pip/_internal/operations/prepare.py

diff -up pip-19.3.1/tests/data/src/extension/extension.c.pip7873 pip-19.3.1/tests/data/src/extension/extension.c

diff -up pip-19.3.1/tests/data/src/extension/setup.py.pip7873 pip-19.3.1/tests/data/src/extension/setup.py

--- pip-19.3.1/tests/data/src/extension/setup.py.pip7873	2022-05-24 08:34:03.285054864 -0600

+++ pip-19.3.1/tests/data/src/extension/setup.py	2022-05-24 08:34:03.285054864 -0600

@@ -0,0 +1,4 @@

+from setuptools import Extension, setup

+

+module = Extension('extension', sources=['extension.c'])

+setup(name='extension', version='0.0.1', ext_modules = [module])

diff -up pip-19.3.1/tests/functional/test_wheel.py.pip7873 pip-19.3.1/tests/functional/test_wheel.py

--- pip-19.3.1/tests/functional/test_wheel.py.pip7873	2019-10-17 13:32:34.000000000 -0600

+++ pip-19.3.1/tests/functional/test_wheel.py	2022-05-24 08:34:03.285054864 -0600

@@ -1,6 +1,7 @@

 """'pip wheel' tests"""

 import os

 import re

+import sys

 from os.path import exists

 import pytest

@@ -228,6 +229,24 @@ def test_pip_wheel_with_user_set_in_conf

     assert "Successfully built withpyproject" in result.stdout, result.stdout

+@pytest.mark.skipif(sys.platform.startswith('win'),

+                    reason='The empty extension module does not work on Win')

+def test_pip_wheel_ext_module_with_tmpdir_inside(script, data, common_wheels):

+    tmpdir = data.src / 'extension/tmp'

+    tmpdir.mkdir()

+    script.environ['TMPDIR'] = str(tmpdir)

+

+    # To avoid a test dependency on a C compiler, we set the env vars to "noop"

+    # The .c source is empty anyway

+    script.environ['CC'] = script.environ['LDSHARED'] = str('true')

+

+    result = script.pip(

+        'wheel', data.src / 'extension',

+        '--no-index', '-f', common_wheels

+    )

+    assert "Successfully built extension" in result.stdout, result.stdout

+

+

 @pytest.mark.network

 def test_pep517_wheels_are_not_confused_with_other_files(script, tmpdir, data):

     """Check correct wheels are copied. (#6196)