get_dirs_from_args handles paths with invalid syntax

Fix #7638

changelog/7638.bugfix.rst

@@ -0,0 +1 @@
+Fix handling of command-line options that appear as paths but trigger an OS-level syntax error on Windows, such as the options used internally by ``pytest-xdist``.

src/_pytest/config/findpaths.py

@@ -1,6 +1,5 @@
 import itertools
 import os
-import sys
 from typing import Dict
 from typing import Iterable
 from typing import List
@@ -146,21 +145,14 @@ def get_dirs_from_args(args: Iterable[str]) -> List[Path]:
             return path
         return path.parent
 
-    if sys.version_info < (3, 8):
-
     def safe_exists(path: Path) -> bool:
-            # On Python<3.8, this can throw on paths that contain characters
+        # This can throw on paths that contain characters unrepresentable at the OS level,
-            # unrepresentable at the OS level.
+        # or with invalid syntax on Windows
         try:
             return path.exists()
         except OSError:
             return False
 
-    else:
-
-        def safe_exists(path: Path) -> bool:
-            return path.exists()
-
     # These look like paths but may not exist
     possible_paths = (
         absolutepath(get_file_part_from_node_id(arg))

testing/test_findpaths.py

@@ -2,6 +2,7 @@ from textwrap import dedent
 
 import pytest
 from _pytest.config.findpaths import get_common_ancestor
+from _pytest.config.findpaths import get_dirs_from_args
 from _pytest.config.findpaths import load_config_dict_from_file
 from _pytest.pathlib import Path
 
@@ -108,3 +109,17 @@ class TestCommonAncestor:
         fn = tmp_path / "foo.py"
         fn.touch()
         assert get_common_ancestor([fn]) == tmp_path
+
+
+def test_get_dirs_from_args(tmp_path):
+    """get_dirs_from_args() skips over non-existing directories and files"""
+    fn = tmp_path / "foo.py"
+    fn.touch()
+    d = tmp_path / "tests"
+    d.mkdir()
+    option = "--foobar=/foo.txt"
+    # xdist uses options in this format for its rsync feature (#7638)
+    xdist_rsync_option = "popen=c:/dest"
+    assert get_dirs_from_args(
+        [str(fn), str(tmp_path / "does_not_exist"), str(d), option, xdist_rsync_option]
+    ) == [fn.parent, d]