Overflow checks in bodies are missing

[volsa]

Is your feature request related to a problem? Please describe. The following code

FUNCTION main : DINT
    VAR
        x : SINT := 1000000;
    END_VAR
        x := 1000000;
END_FUNCTION

will return an overflow error for the assignment in the VAR-block, but not for the assignment in the implementation / body. Specficially when compiling the code we get the following output

warning: This will overflow for type SINT
  ┌─ target/demo.st:3:21
  │
3 │         x : SINT := 1000000;
  │                     ^^^^^^^ This will overflow for type SINT

but the one in the body is missing.

Describe the solution you'd like Check overflows (where possible) in the body