Deprecate case-variables

[Paul Backus]

On Tuesday, 16 May 2023 at 17:31:58 UTC, Meta wrote:
>
> Aren't case variables useful for creating jump tables much more 
> succinctly? It seems like that is a use case that should be 
> carefully considered.

"Case variables" refers specifically to the use of a runtime 
variable in a case label, like this:

     int x = 1;
     const int n = readln.strip.to!int;

     switch (x)
     {
         case n: // <-- case variable
             writeln("x == n");
             break;
         default:
             writeln("x != n");
             break;
     }

Even if we remove case variables, the ability to specify multiple 
values in a single case label will remain, as long as those 
values are all compile-time constants. So this change would not 
make it any harder to write succinct jump tables.