(csharp) Contextual keywords are highlighted incorrectly

Describe the issue

In C#, there are “contextual keywords”, which are not always treated as keywords. They are highlighted incorrectly in a context where they are not treated as a keyword.

Sample Code to Reproduce

public class Move
{
    public Move(Point from, Point to) // from should not be highlighted here.
    {
        var x = from x in y where x.z == 0 select x; // from is highlighted here. (Note that GitHub handles it correctly)
    }
}

Expected behavior

from isn’t highlighted as a keyword.

Additional context

In other contexts (LINQ query), from should be highlighted as a keyword.

Note: This issue may not be limited to from.

[joshgoebel]

Tagging auto-close… we’re no longing going to leave hard contextual parsing issues open as these are by their nature impossible to fix fully without a full parser. If someone would like to work on a PR for the few simple cases, this would be welcome, but it’s not a reason for such issues to become zombie issues forever.

[joshgoebel]

@Youssef1313 Want to try your hand at a PR? I feel like we need a special rule just for from or join that looks ahead and makes sure it has word word? in and then remove them from the regular keyword list.

I think in could stay in the regular list, correct?