Refactoring with .NET 5 Unsafe APIs

[Sergio0694]

Close #3509

PR Type

What kind of change does this PR introduce?

• Refactoring (no functional changes, no api changes)

What is the current behavior?

There are a number of usages of Unsafe.AsRef<T>(null) and similar that are verbose.

What is the new behavior?

These occurrences are replaced using the new Unsafe.NullRef<T>() and Unsafe.IsNullRef<T>(...) APIs.

Notes

Leaving this as draft as the new System.Runtime.CompilerServices.Unsafe package is still in release candidate.

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Pull Request has been submitted to the documentation repository instructions. Link:
• Sample in sample app has been added / updated (for bug fixes / features)
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• Tests for the changes have been added (for bug fixes / features) (if applicable)
• Header has been added to all new source files (run build/UpdateHeaders.bat)
• Contains NO breaking changes

[ghost]

Thanks Sergio0694 for opening a Pull Request! The reviewers will test the PR and highlight if there is any conflict or changes required. If the PR is approved we will proceed to merge the pull request 🙌

[Sergio0694]

Fixed merge conflicts and marked as ready for review, as .NET 5 RC1 is released with "go live" license! 🚀

[Sergio0694]

The 5.0.0 packages are out on NuGet and I've updated this PR, we're good to go! 🚀🚀🚀
Will update all the others and fix conflicts as soon as this one is merged, especially #3356!

[Sergio0694]

The CI failed with this error:

Test method UnitTests.Helpers.Test_ColorHelper.Test_ColorHelper_ToColor_ScreenColor threw exception:
System.FormatException: Input string was not in a correct format.

I've seen this on and off seemingly at random in a number of failed CI runs across multiple PRs of mine now. My guess is that that crash was caused by the double.Parse calls being used to parse the screen color in the ToColor extension, here:

https://github.com/windows-toolkit/WindowsCommunityToolkit/blob/66be202cbb94413e2fdec35ec5e275e9d9a0e979/Microsoft.Toolkit.Uwp/Helpers/ColorHelper.cs#L94-L97

Basically, whenever the CI happened to run in a server in some region with the decimal specified using , instead of . to separate decimal digits, this would just crash with a FormatException. Fixed it in 63ad9e7 by manually using invariant culture for the parsing calls, that should hopefully stop these crashes from happening in the future and make the method more reliable.

EDIT: all is fine now! 🎉

[ghost]

Hello @michael-hawker!

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