short s, t; t = -s: no (longer) works: Deprecation: integral promotion not done for -s, use

[kdevel via Digitalmars-d-learn]

I don't get the point of the deprecation message:

--- intprom.d
import std.stdio;
void main ()
{
   short s, t;
   t = -s;
}
---

$ dmd intprom.d
intprom.d(6): Deprecation: integral promotion not done for -s, 
use '-transition=intpromote' switch or -cast(int)(s)

What shall I do in order to get my template code

void mymain (T) ()
{
   :
      b[i] = -b [i];
   :
}

compiled for any type for which negation is defined?