GH-103525: Improve exception message from pathlib.PurePath()

Check that arguments are strings before calling `os.path.join()`. Also improve performance of `PurePath(PurePath(...))` while we're in the area: we now use the *unnormalized* string path of such arguments.
python · barneygale · May 2, 2023 · Apr 13, 2023 · Apr 13, 2023 · Apr 29, 2023
commit 6c1131e8dff2c701414f6d776a0548781367e3cd
@@ -300,18 +300,24 @@ def __reduce__(self):
        return (self.__class__, self.parts)

    def __init__(self, *args):
-        if not args:
-            path = ''
-        elif len(args) == 1:
-            path = os.fspath(args[0])
+        paths = []
+        for arg in args:
+            if isinstance(arg, PurePath):
+                path = arg._raw_path
+            else:
+                path = os.fspath(arg)
+                if not isinstance(path, str):
+                    raise TypeError(
+                        "argument should be a str or an os.PathLike "
+                        "object where __fspath__ returns a str, "
+                        f"not {type(path).__name__!r}")
+            paths.append(path)
+        if len(paths) == 0:
+            self._raw_path = ''
+        elif len(paths) == 1:
+            self._raw_path = paths[0]
        else:
-            path = self._flavour.join(*args)
-        if not isinstance(path, str):
-            raise TypeError(
-                "argument should be a str or an os.PathLike "
-                "object where __fspath__ returns a str, "
-                f"not {type(path).__name__!r}")
-        self._raw_path = path
+            self._raw_path = self._flavour.join(*paths)

    @classmethod
    def _parse_path(cls, path):
@@ -615,7 +621,7 @@ def joinpath(self, *args):
        paths) or a totally different path (if one of the arguments is
        anchored).
        """
-        return self.__class__(self._raw_path, *args)
+        return self.__class__(self, *args)

    def __truediv__(self, key):
        try:
@@ -625,7 +631,7 @@ def __truediv__(self, key):

    def __rtruediv__(self, key):
        try:
-            return type(self)(key, self._raw_path)
+            return type(self)(key, self)
        except TypeError:
            return NotImplemented

@@ -859,7 +865,7 @@ def absolute(self):
            cwd = self._flavour.abspath(self.drive)
        else:
            cwd = os.getcwd()
-        return type(self)(cwd, self._raw_path)
+        return type(self)(cwd, self)

    def resolve(self, strict=False):
        """

@@ -81,9 +81,9 @@ def test_bytes(self):
                   r"where __fspath__ returns a str, not 'bytes'")
        with self.assertRaisesRegex(TypeError, message):
            P(b'a')
-        with self.assertRaises(TypeError):
+        with self.assertRaisesRegex(TypeError, message):
            P(b'a', 'b')
-        with self.assertRaises(TypeError):
+        with self.assertRaisesRegex(TypeError, message):
            P('a', b'b')
        with self.assertRaises(TypeError):
            P('a').joinpath(b'b')

diff --git a/Misc/NEWS.d/next/Library/2023-04-13-19-43-15.gh-issue-103525.uY4VYg.rst b/Misc/NEWS.d/next/Library/2023-04-13-19-43-15.gh-issue-103525.uY4VYg.rst
@@ -0,0 +1,2 @@
+Fix misleading exception message when mixed ``str`` and ``bytes`` arguments
+are supplied to :class:`pathlib.PurePath` and :class:`~pathlib.Path`.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Fix misleading exception message when mixed ``str`` and ``bytes`` arguments
		are supplied to :class:`pathlib.PurePath` and :class:`~pathlib.Path`.