Bug report

(editor's note: the description below indicates that realpath() is unaffected, but that's not correct - see comment)

If a file descriptor is created in /proc/self/fd/ and then passed to pathlib.Path, the resolve() method produces a result which is no longer a real and valid path to the file.
MRE, including os.path.realpath for comparison:

import os, pathlib
fd = os.memfd_create("myfd")
print(pathlib.Path(f"/proc/self/fd/{fd}").resolve())
# /memfd:myfd (deleted)
print(os.path.realpath("/proc/self/fd/4"))
# /proc/227671/fd/4

This can occur easily if another program uses the /proc/self/fd/ mechanism to pass temporary files to a python application.
For example, using ZSH on linux:

$ python -c 'import pathlib, sys; print(pathlib.Path(sys.argv[1]).resolve())' <(echo 'hi')
/proc/234888/fd/pipe:[331484707]

I looked at pathlib.py and in 3.11 it looks like it's primarily relying on realpath, so I'm not clear on where or how the discrepancy gets introduced. I'm sure I don't understand something about pathlib which explains.

Your environment

• CPython versions tested on: 3.10, 3.11
• Operating system and architecture: Linux