Why doesn't C# support this pattern matching?

Question

C++ / C#

why can't I write like this:
var matched = obj is { Id: variable }
are there any libraries that will allow me to do this?

Answer 1

C# just doesn't know how to use variables in pattern matching and switch-case.
In this case, you can write like this: Well, or like this, if the case is more complex:
var matched = obj != null && obj.Id == variable;

var matched = obj is { Id: var id} && id == variable;