not pattern does not compile with same named class

[AnakinRaW]

Consider the following code:

object o = new not();
if (o is not) { } // Compile error
if (o is not not) { } // Works fine

public class not { }

On VS 16.8.3 Roslyn gives me CS8504.

Are there any plans on fixing this (e.g. by making not a keyword) or was this intentionally not considered (e.g. due to backwards compatibility)?

[333fred]

This type of scenario was intentionally not (no pun intended) considered. Lowercase type names are bad style in C#, and while we make every effort to not break this type of scenario, it can happen (for example, in C# 9, putting record foo; in a type always means generate a record named foo, regardless of whether there is a type also named record). For your scenario, escaping with @ works:

object o = null;
_ = o is @not;

public class not
{
}