mat2 bar(void)
{
   int i = 0, j = 0;
   mat2 k;
   for (j = 0; j < 2; j++) {
       for (i = 0; i < 2; i++) {
           k[j][i] = 1;
       }
   }

   return k;
}

mat2 foo = bar(); 

void main(void)
{
    gl_FrontColor = vec4(1.0, 0.0, 0.0, 1.0);
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
}