Document System.Guid

[carlossanlop]

No description provided.

[rpetrusha]

I've left some suggestions and comments, @carlossanlop.

[rpetrusha]

Suggested change

<exception cref="T:System.ArgumentNullException"><paramref name="input" /> is <see langword="null" />.</exception>

[carlossanlop]

@rpetrusha Thanks for catching this. I tested this:

static void Main(string[] args)
{
    ReadOnlySpan<char> input = null;
    Guid guid = Guid.Parse(input);
}

and we end up throwing System.FormatException: Unrecognized Guid format.

Looking at the code for Parse, this method does not check if input is null, and it directly passes the argument to the private method TryParseGuid, which also does not check if input is null.
But it seems that calling Trim on a null ReadOnlySpan<char> will actually be calling it on an empty span. Not sure how this works, but it seems the span never becomes null. I'll dig more into this later.

[rpetrusha]

A span can't be null, @carlossanlop, since it's a value type.

[rpetrusha]

Thanks, @carlossanlop. I'll merge this PR now.