Fix Item4 is missing in some ValueTuples' IStructuralEquatable.Equals

[hamarb123]

Fixes #91457

[ghost]

Tagging subscribers to this area: @dotnet/area-system-runtime
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Fixes #91457

Author:	hamarb123
Assignees:	-
Labels:	area-System.Runtime
Milestone:	-

[stephentoub]

Thanks!

[stephentoub]

@jeffhandley, we should backport this to release/8.0.

[EgorBo]

@jeffhandley, we should backport this to release/8.0.

It seems that it was introduced in net6.0 so do we need to backport it to 6.0 and 7.0 as well?

[jeffhandley]

With the potential for data loss that could occur in customers' applications, I do think we should backport this to 6.0 and 7.0 too.

[jeffhandley]

/backport to release/8.0
/backport to release/7.0-staging
/backport to release/6.0-staging

[github-actions]

Started backporting to release/8.0: https://github.com/dotnet/runtime/actions/runs/6052140869

[jeffhandley]

/backport to release/7.0-staging

[jeffhandley]

/backport to release/6.0-staging

[github-actions]

Started backporting to release/7.0-staging: https://github.com/dotnet/runtime/actions/runs/6052193377

[github-actions]

Started backporting to release/6.0-staging: https://github.com/dotnet/runtime/actions/runs/6052195472

[jeffhandley]

@dotnet/compat -- Do you have any compatibility concerns with the 6.0 and 7.0 backports of this functional fix? It's clearly a behavioral change for the better, but could there be any surprises for customers when the patch goes through?

[Junjun-zhao]

Adding @marklio @PriyaPurkayastha for more comments.

Is this fix merged into the latest .NET 8 RC2 build? We conducted a test pass with the latest build dotnet-sdk-8.0.100-rc.2.23456.6, and no related issues were found till now.