Decorated the out parameter of ResourceIdentifier.TryParse() with MaybeNullWhen

[abatishchev]

Split from #39060.

Updated:

public static bool TryParse(string input, out ResourceIdentifier? result)

with:

public static bool TryParse(string input, [MaybeNullWhen(false)] out ResourceIdentifier? result)

[github-actions]

Thank you for your contribution @abatishchev! We will review the pull request and get back to you soon.

[m-nash]

Tested this to validate and apparently the warning always exists if the out var is nullable so the attribute seems to make no difference.

If we change to

public static bool TryParse(string input, [MaybeNullWhen(false)] out ResourceIdentifier result)

Then it seems to work as expected. I don't now the backwards compatibility rules on nullable annotation changes. @KrzysztofCwalina is there another link I should be using besides https://learn.microsoft.com/en-us/dotnet/core/compatibility/library-change-rules to check?

My guess is going from ResourceIdentifier to ResourceIdentifier? is fine but going from ResourceIdentifier? to ResourceIdentifier is not?

namespace nullable
{
    internal class Program
    {
        static void Main(string[] args)
        {
            if (Foo.TryParse("x", out var y))
                Console.WriteLine(y.Length); //does not give warning

            Foo.TryParse("x", out var y2);
            Console.WriteLine(y2.Length); //gives warning cs8602
        }
    }

    internal class Foo
    {
        public static bool TryParse(string x, [MaybeNullWhen(false)] out string y)
        {
            y = null;
            return false;
        }
    }
}

[azure-sdk]

API change check

API changes are not detected in this pull request.