#include <complex.h>
#include <stdint.h>
#include <stdio.h>

int main()
{
    float complex x = I + I / 3 * I / 2;
    short int complex y = I + I / 3 * I / 2;
    int16_t complex z = I + I / 3 * I / 2;       /* Why ? */
    printf("x=(%+f,%+f)n", creal(x), cimag(x));
    printf("y=(%+f,%+f)n", creal(y), cimag(y));
    printf("z=(%+f,%+f)n", creal(z), cimag(z));  /* Why ? */
    return 0;
}

In file included from ./complex.c:1:0:
./complex.c: In function ‘main’:
./complex.c:9:13: error: two or more data types in declaration specifiers
     int16_t complex z = I + I / 3 * I / 2;       /* Why ? */

gcc-5 --std=c99 ./complex.c -o ./complex
gcc-4.9 --std=c99 ./complex.c -o ./complex