Given the following code:

#define MAX(a,b) 
   ({ __typeof__ (a) _a = (a); 
       __typeof__ (b) _b = (b); 
     _a > _b ? _a : _b; })

int main() {
  short int a=1,b=2;
  a=MAX(a,b);
  return 0;
}

gcc -Wconversion gives the following warning:

toto.c: In function ‘main’:
toto.c:2:4: warning: conversion from ‘int’ to ‘short int’ may change value [-Wconversion]
    2 |    ({ __typeof__ (a) _a = (a); 
      |    ^
toto.c:8:5: note: in expansion of macro ‘MAX’
    8 |   a=MAX(a,b);

Does anybody know why? Eveything is a short int from start to end.