Fix Clear and Remove after Sort in TreeView

[gpetrou]

Fixes #10376

Proposed changes

• Fix Clear and Remove after Sort in TreeView. It looks like we broke this in Use generic list instead of array in TreeNode #9078 by following Use generic list instead of array in TreeNode #9078 (comment). Perhaps we should just bring back the old method instead of using the current approach?

Microsoft Reviewers: Open in CodeFlow

[JeremyKuhne]

Thanks, @gpetrou. I've added comments.

I'm thinking about whether or not we should put back the original logic. There is some risk that it will change behavior with nodes that are equivalent.

In general, one has to be extremely careful with messing with sort algorithms or hashes.

[JeremyKuhne]

@gpetrou It would be good to make sure we have tests that exercise the TreeView nodes and validate their indices after manipulation. Recursive sorting should be captured as well.

Whatever we do here will be in the February update (the next update is already locked) so we've got some time to make sure we've got good test coverage.

[JeremyKuhne]

Added another comment.

[JeremyKuhne]

@gpetrou we discussed this further as a team and we want to put back the original sorting logic to avoid any further regressions around visibility of index changes during sorting and sorting behavior with equivalent nodes. Are you ok with doing this?

[JeremyKuhne]

One more nit. Are you up for adding index validation tests?

[lonitra]

🚢

[lonitra]

/backport to release/8.0

[github-actions]

Started backporting to release/8.0: https://github.com/dotnet/winforms/actions/runs/7038495410

[github-actions]

@lonitra backporting to release/8.0 failed, the patch most likely resulted in conflicts:

$ git am --3way --ignore-whitespace --keep-non-patch changes.patch

Applying: Fix Clear and Remove after Sort in TreeView
Using index info to reconstruct a base tree...
A	src/System.Windows.Forms/src/System/Windows/Forms/Controls/TreeView/TreeNode.cs
M	src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/TreeViewTests.cs
Falling back to patching base and 3-way merge...
Auto-merging src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/TreeViewTests.cs
Auto-merging src/System.Windows.Forms/src/System/Windows/Forms/TreeNode.cs
CONFLICT (content): Merge conflict in src/System.Windows.Forms/src/System/Windows/Forms/TreeNode.cs
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Fix Clear and Remove after Sort in TreeView
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
Error: The process '/usr/bin/git' failed with exit code 128

Please backport manually!