Dynamic Syntax Checking shows errors for switch case statement

In the µVision editor(v5.13.0.0), the Dynamic Syntax Checking shows me an error for this switch case statement. Here is an example:

switch (i) { case (int)("AB"[0]): break; default: break; }

But when i use the µVision editor(v5.23.0.0),the Dynamic Syntax Checking don't shouw error.