This comes from csharp-mode's attribute recognition code; see emacs-csharp/csharp-mode#142
I've had a look, but I can't see what the problem is. In particular, if I insert a real semicolon instead of an attribute, then the fontification is correct.
Since this is a fairly minor bug, and without attribute parsing indentation is broken, I think the best thing to do is wait for the fix in csharp-mode, and copy it!
This comes from csharp-mode's attribute recognition code; see emacs-csharp/csharp-mode#142
I've had a look, but I can't see what the problem is. In particular, if I insert a real semicolon instead of an attribute, then the fontification is correct.
Since this is a fairly minor bug, and without attribute parsing indentation is broken, I think the best thing to do is wait for the fix in csharp-mode, and copy it!