multiply case and variable v may not have been initialized error

of course no, but it very useful feature(if working well) that compiler gives information that I set value in all CASEs and now I can't compile  and spent some time to look for case without setting value

I think you don't understand problem, I didn't tested it but probably shows the same like my more complicated:

var v, i;

i=1;
switch(i)
{
  case 1:
  case 2:
    v = 123;
    break;
  default:
     v = 321;
  //break unnecessary
}

dc.drawText....

this code probably gives error, comment case 1 or case 2 no error

of course no, but it very useful feature(if working well) that compiler gives information that I set value in all CASEs and now I can't compile  and spent some time to look for case without setting value

I think you don't understand problem, I didn't tested it but probably shows the same like my more complicated:

var v, i;

i=1;
switch(i)
{
  case 1:
  case 2:
    v = 123;
    break;
  default:
     v = 321;
  //break unnecessary
}

dc.drawText....

this code probably gives error, comment case 1 or case 2 no error

not working but error

BUILD: ERROR: fenix6spro: ... :912: Variable v may not have been initialized.
BUILD: ERROR: fenix6spro: ... .mc:965: Variable icon may not have been initialized.
BUILD: Complete
Aborting launch due to failed build.

Strange thing that happens when you try to launch, after saving and compilation is no error and  BUILD: Complete.
Is switch/case analysed in steps? You can write:

case 1:
  br;//not break

and error only when launching...

and you can write also :

case 1:
  ...
  break;
case 1:
  ...
  break;

as Brandon.ConnectIQ says, technically OKbut it should be a small warning (yes, I know it can be case variable: and variable is known in runtime but it's developer's risk when).

Yep I can recreate this. For completeness here's a full test case:

        var v, i;
        i = 1;
        switch (i)
        {
            case 1:
            case 2:
                v = 123;
                break;
            default:
                v = 321;
            //break unnecessary
        }

        System.println(v); // warning here: Variable v may not have been initialized in all code paths.

This is clearly a compiler bug.