bpo-34699: allow path-like objects in program arguments in Windows

Lib/subprocess.py

@@ -515,7 +515,7 @@ def list2cmdline(seq):
     # "Parsing C++ Command-Line Arguments"
     result = []
     needquote = False
-    for arg in seq:
+    for arg in map(os.fspath, seq):
         bs_buf = []
 
         # Add a space to separate this argument from the others

Lib/test/test_subprocess.py

@@ -363,6 +363,18 @@ def test_cwd_with_pathlike(self):
         temp_dir = self._normalize_cwd(temp_dir)
         self._assert_cwd(temp_dir, sys.executable, cwd=FakePath(temp_dir))
 
+    def test_args_with_pathlike(self):
+        temp_dir = tempfile.gettempdir()
+        temp_dir = self._normalize_cwd(temp_dir)
+        p = subprocess.Popen([FakePath(sys.executable), "-c",
+                              "import sys; sys.exit(47)"])
+        self.assertEqual(p.wait(), 47)
+        p = subprocess.Popen([sys.executable, "-c",
+                              "import sys; print(sys.argv[1], end='')",
+                              FakePath(temp_dir)], stdout=subprocess.PIPE)
+        with p:
+            self.assertEqual(os.fsdecode(p.stdout.read()), temp_dir)
+
     @unittest.skipIf(mswindows, "pending resolution of issue #15533")
     def test_cwd_with_relative_arg(self):
         # Check that Popen looks for args[0] relative to cwd if args[0]
@@ -1048,6 +1060,8 @@ def test_no_leaking(self):
     def test_list2cmdline(self):
         self.assertEqual(subprocess.list2cmdline(['a b c', 'd', 'e']),
                          '"a b c" d e')
+        self.assertEqual(subprocess.list2cmdline(['a b c', 'd', FakePath('e')]),
+                         '"a b c" d e')
         self.assertEqual(subprocess.list2cmdline(['ab"c', '\\', 'd']),
                          'ab\\"c \\ d')
         self.assertEqual(subprocess.list2cmdline(['ab"c', ' \\', 'd']),

Misc/NEWS.d/next/Library/2018-09-15-15-32-04.bpo-34699.Q7XUTY.rst

@@ -0,0 +1,3 @@
+Currently, the `subprocess.Popen` function allows for path-like objects in
+the argument list for POSIX but not in Windows. This PR makes Windows'
+`subprocess.Popen` accept path-like objects in the argument list.