Pattern matching - variable in scope outside if-block

Question

I\'m trying to understand why y is in scope in the following example:

static void Main(string[] args)
{
    int x = 1;
    if (x is int y) { }

         


        

Answer 1

That's is something I had found in VS15P4 (or P5) and it was being tracked on GitHub:

Definite assignment versus pattern-matching when pattern always matches #14651

Putting aside all the discussions, it is a scoping issue which occurs when the pattern always matches, as the title suggests.

I thought it was fixed before RC so I haven't actually tested afterwards but it seems the issue still persists.

Let's see if it will be fixed in the actual release, which is tomorrow :)