[Python-checkins] gh-83006: Document behavior of `shutil.disk_usage` for non-mounted filesystems on Unix (#107031)

[ambv]

https://github.com/python/cpython/commit/6e5f2235f3754307292c7d8d3698958136b5e311
commit: 6e5f2235f3754307292c7d8d3698958136b5e311
branch: main
author: Matthieu Caneill <matthieucan at users.noreply.github.com>
committer: ambv <lukasz at langa.pl>
date: 2023-07-22T17:58:06+02:00
summary:

gh-83006: Document behavior of `shutil.disk_usage` for non-mounted filesystems on Unix (#107031)

files:
A Misc/NEWS.d/next/Library/2023-07-22-15-51-33.gh-issue-83006.21zaCz.rst
M Doc/library/shutil.rst

diff --git a/Doc/library/shutil.rst b/Doc/library/shutil.rst
index 5bd80b10a6580..7699d22a72aaf 100644
--- a/Doc/library/shutil.rst
+++ b/Doc/library/shutil.rst
@@ -399,6 +399,12 @@ Directory and files operations
    total, used and free space, in bytes. *path* may be a file or a
    directory.
 
+   .. note::
+
+      On Unix filesystems, *path* must point to a path within a **mounted**
+      filesystem partition. On those platforms, CPython doesn't attempt to
+      retrieve disk usage information from non-mounted filesystems.
+
    .. versionadded:: 3.3
 
    .. versionchanged:: 3.8
diff --git a/Misc/NEWS.d/next/Library/2023-07-22-15-51-33.gh-issue-83006.21zaCz.rst b/Misc/NEWS.d/next/Library/2023-07-22-15-51-33.gh-issue-83006.21zaCz.rst
new file mode 100644
index 0000000000000..e64d186082843
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-07-22-15-51-33.gh-issue-83006.21zaCz.rst
@@ -0,0 +1,2 @@
+Document behavior of :func:`shutil.disk_usage` for non-mounted filesystems
+on Unix.