use tempfile.TemporaryDirectory to cleanup garbage- dir

Python has a very nice rm_rf hidden in
tempfile.TemporaryDirectory._rmtree we can use it to cleanup our
"garbage-" dir
https://github.com/python/cpython/blob/3d43f1dce3e9aaded38f9a2c73e3c66acf85505c/Lib/tempfile.py#L784-L812

Author: graingert

src/_pytest/pathlib.py

@@ -6,6 +6,7 @@
 import os
 import shutil
 import sys
+import tempfile
 import uuid
 import warnings
 from enum import Enum
@@ -254,11 +255,10 @@ def maybe_delete_a_numbered_dir(path: Path) -> None:
     lock_path = None
     try:
         lock_path = create_cleanup_lock(path)
-        parent = path.parent
-
-        garbage = parent.joinpath(f"garbage-{uuid.uuid4()}")
-        path.rename(garbage)
-        rm_rf(garbage)
+        with tempfile.TemporaryDirectory(
+            prefix="garbage-", dir=os.fsdecode(path.parent)
+        ) as garbage:
+            path.replace(garbage)
     except OSError:
         #  known races:
         #  * other process did a cleanup at the same time

testing/test_tmpdir.py

@@ -435,10 +435,29 @@ def test(tmp_path):
             fn.write_text('hello')
             mode = os.stat(str(fn)).st_mode
             os.chmod(str(fn), mode & ~stat.S_IREAD)
-    """
+        """
     )
     result = testdir.runpytest("--basetemp=tmp")
     assert result.ret == 0
     # running a second time and ensure we don't crash
     result = testdir.runpytest("--basetemp=tmp")
     assert result.ret == 0
+
+
+def test_basetemp_with_not_executable_dirs(testdir):
+    """Integration test for #7940"""
+    testdir.makepyfile(
+        """
+        def test(tmp_path):
+            p = tmp_path / "ham" / "spam" / "eggs"
+            p.parent.mkdir(parents=True)
+            p.touch(mode=0)
+            for p in p.parents:
+                if p == tmp_path:
+                    break
+                p.chmod(mode=0)
+        """
+    )
+    assert testdir.runpytest("--basetemp=tmp").ret == 0
+    # running a second time and ensure we don't crash
+    assert testdir.runpytest("--basetemp=tmp").ret == 0