resolve conflicts with GH-19611

python · miss-islington · Oct 28, 2022 · Apr 30, 2020 · May 28, 2020 · May 15, 2021
commit 6d721a0ee1fbc841fd555d3acf173f56f36ba410
@@ -549,25 +549,24 @@ Pure paths provide the following methods and properties:
       >>> p.relative_to('/usr')
       Traceback (most recent call last):
         File "<stdin>", line 1, in <module>
-        File "pathlib.py", line 940, in relative_to
+        File "pathlib.py", line 941, in relative_to
           raise ValueError(error_message.format(str(self), str(formatted)))
-      ValueError: '/etc/passwd' does not start with '/usr'
+      ValueError: '/etc/passwd' is not in the subpath of '/usr' OR one path is relative and the other is absolute.
       >>> p.relative_to('/usr', strict=False)
       PurePosixPath('../etc/passwd')
       >>> p.relative_to('foo', strict=False)
       Traceback (most recent call last):
         File "<stdin>", line 1, in <module>
-        File "pathlib.py", line 940, in relative_to
+        File "pathlib.py", line 941, in relative_to
           raise ValueError(error_message.format(str(self), str(formatted)))
-      ValueError: '/etc/passwd' is not related to 'foo'
+      ValueError: '/etc/passwd' is not on the same drive as 'foo' OR one path is relative and the other is absolute.
 
-   If the path doesn't start with *other* and *strict* is ``True``,
-   :exc:`ValueError` is raised.  If *strict* is ``False`` and the paths are
-   not both relative or both absolute :exc:`ValueError` is raised (on Windows
-   both paths must reference the same drive as well).
+   If the path doesn't start with *other* and *strict* is ``True``, :exc:`ValueError` is raised.  If *strict* is ``False`` and one path is relative and the other is absolute or if they reference different drives :exc:`ValueError` is raised.
 
-   .. versionadded:: 3.9
-      The *strict* parameter was added.
+   NOTE: This function is part of :class:`PurePath` and works with strings. It does not check or access the underlying file structure.
+
+   .. versionadded:: 3.10
+      The *strict* argument (pre-3.10 behavior is strict).
 
 
 .. method:: PurePath.with_name(name)

diff --git a/Lib/pathlib.py b/Lib/pathlib.py
@@ -927,14 +927,15 @@ def relative_to(self, *other, strict=True):
             common += 1
         if strict:
             failure = (root or drv) if n == 0 else common != n
-            error_message = "{!r} does not start with {!r}"
+            error_message = "{!r} is not in the subpath of {!r}"
             up_parts = []
         else:
             failure = root != to_root
             if drv or to_drv:
                 failure = cf([drv]) != cf([to_drv]) or (failure and n > 1)
-            error_message = "{!r} is not related to {!r}"
+            error_message = "{!r} is not on the same drive as {!r}"
             up_parts = (n-common)*['..']
+        error_message += " OR one path is relative and the other is absolute."
         if failure:
             formatted = self._format_parsed_parts(to_drv, to_root, to_parts)
             raise ValueError(error_message.format(str(self), str(formatted)))

diff --git a/Misc/NEWS.d/next/Library/2020-04-30-02-15-08.bpo-40358.A4ygqe.rst b/Misc/NEWS.d/next/Library/2020-04-30-02-15-08.bpo-40358.A4ygqe.rst
@@ -1,2 +1 @@
-Add strict parameter in :meth:`pathlib.PurePath.relative_to`. Patch by
-Domenico Ragusa.
+Add strict argument in :meth:`pathlib.PurePath.relative_to`.