is_dir() returns False when called from a path.relative_to(root) result.

[srw]

Bug report

Bug description:

def walk():
   root = Path("src/")
   for path in root.rglob("*"):
      p = path.relative_to(root)
      print(p)
      print(p.is_dir()) # always returns False
      print(path.is_dir())  # returns True when it's a dir

Since path.relative_to() returns a Path it would be correct to either return True or False depending if it's a path (even if it's relative) or an "I_DONT_KNOW" response instead of True or False.

CPython versions tested on:

3.13

Operating systems tested on:

macOS Tahoe 26.0.1

[cmaloney]

I adapted the script to run on the CPython Docs folder, print a little more around the current directory, and only output cases that differ:

Tweaked script to output differences on Doc dir

from pathlib import Path

def walk():
   root = Path("Doc/")
   for path in root.rglob("*"):
      p = path.relative_to(root)
      if p.is_dir() == path.is_dir():
         continue
      print(f"{p=}|{path=}|{Path.cwd()=}")
      print(p.is_dir()) # always returns False
      print(path.is_dir())  # returns True when it's a dir

walk()

Running that I get:

p=PosixPath('tutorial')|path=PosixPath('Doc/tutorial')|Path.cwd()=PosixPath('/Users/cmaloney/projects/python/cpython')
False
True
...

There can see p doesn't contain the Doc/ prefix while path does. .is_dir() in Pathlib uses "stat" to check "is this a directory", and for p.is_dir() that gets "False" because stat doesn't find the directory.

So I think this is working as designed; that "path doesn't exist" and "not a directory" both result in False is an intentional simplification in this case. You can use p.exists() to disambiguate which is given in the examples: https://docs.python.org/3/library/pathlib.html#basic-use

[serhiy-storchaka]

Classical True, False, FileNotFound. https://thedailywtf.com/articles/What_Is_Truth_0x3f_