Incorrect sort order when using tab completion and listing items

Prerequisites

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• Make sure you are able to repro it on the latest released version
• Search the existing issues.
• Refer to the FAQ.
• Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

I am inside a directory that looks as follows. Notice how it’s listing out files in the incorrect order! This applies to tab completion as well and the “broken” items will be completed before the correct items. There must be a sort-order bug someplace…

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a---           5/29/2023  5:26 AM           6060 check_cmake_consistency_config.py    <-- broken; wrong order
-a---           5/29/2023  5:26 AM          14928 check_cmake_consistency.py
-a---           5/29/2023  5:26 AM           5119 check_deprecated.py
-a---           5/29/2023  5:26 AM           6025 check_descriptions.py
-a---           5/29/2023  5:26 AM           2147 check_header_duplicate.py
-a---           5/29/2023  5:26 AM          15793 check_licenses.py
-a---           5/29/2023  5:26 AM           3792 check_mypy_config.py    <-- broken; wrong order
-a---           5/29/2023  5:26 AM           2908 check_mypy.py
-a---           5/29/2023  5:26 AM          13648 check_spelling_c_config.py    <-- broken; wrong order
-a---           5/29/2023  5:26 AM          23475 check_spelling.py
-a---           5/29/2023  5:26 AM           2524 check_unused_defines.py

Expected behavior

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a---           5/29/2023  5:26 AM          14928 check_cmake_consistency.py
-a---           5/29/2023  5:26 AM           6060 check_cmake_consistency_config.py
-a---           5/29/2023  5:26 AM           5119 check_deprecated.py
-a---           5/29/2023  5:26 AM           6025 check_descriptions.py
-a---           5/29/2023  5:26 AM           2147 check_header_duplicate.py
-a---           5/29/2023  5:26 AM          15793 check_licenses.py
-a---           5/29/2023  5:26 AM           2908 check_mypy.py
-a---           5/29/2023  5:26 AM           3792 check_mypy_config.py
-a---           5/29/2023  5:26 AM          23475 check_spelling.py
-a---           5/29/2023  5:26 AM          13648 check_spelling_c_config.py
-a---           5/29/2023  5:26 AM           2524 check_unused_defines.py

Actual behavior

Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
-a---           5/29/2023  5:26 AM           6060 check_cmake_consistency_config.py    <-- broken; wrong order
-a---           5/29/2023  5:26 AM          14928 check_cmake_consistency.py
-a---           5/29/2023  5:26 AM           5119 check_deprecated.py
-a---           5/29/2023  5:26 AM           6025 check_descriptions.py
-a---           5/29/2023  5:26 AM           2147 check_header_duplicate.py
-a---           5/29/2023  5:26 AM          15793 check_licenses.py
-a---           5/29/2023  5:26 AM           3792 check_mypy_config.py    <-- broken; wrong order
-a---           5/29/2023  5:26 AM           2908 check_mypy.py
-a---           5/29/2023  5:26 AM          13648 check_spelling_c_config.py    <-- broken; wrong order
-a---           5/29/2023  5:26 AM          23475 check_spelling.py
-a---           5/29/2023  5:26 AM           2524 check_unused_defines.py

Error details

No response

Environment data

Name                           Value
----                           -----
PSVersion                      7.3.4
PSEdition                      Core
GitCommitId                    7.3.4
OS                             Microsoft Windows 10.0.22621
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Visuals

No response

[mklement0]

.NET’s sorting behavior on Windows changed with .NET 5’s move to cross-platform, ICU-based internationalization, as described in .NET globalization and ICU. PowerShell v7.1+ is based on .NET 5+

Therefore, the sort order of _ vs. . is now different relative to Windows PowerShell (based on .NET Framework, which uses Windows-specific NLS sorting rules), and explains your experience:

# WinPS:    -> '.', '_' 
# PS v7.1+: -> '_', '.' 
'.', '_' | Sort-Object

In PS Core, Get-ChildItem performs its own sorting on all platforms, using case-insensitive current-culture sorting (as Sort-Object does by default): https://github.com/PowerShell/PowerShell/blob/1f02772fd97fea7395fbb7b68e2befd5790db392/src/System.Management.Automation/namespaces/FileSystemProvider.cs#L1632-L1633.

[MartinGC94]

.NET’s sorting behavior on Windows changed with .NET 5’s move to cross-platform, ICU-based internationalization, as described in .NET globalization and ICU.

Neat. From that article it seems you can see an environment variable to revert this change in behavior:

Of course you should be careful about setting this because it affects more than just sorting but it’s good to know that users have some control over this.