OK, there are warnings like,
sdl.c: At top level:
sdl.c:548:3: warning: 'current_y' is static but used in inline function 'LineTo' which is not static
548 | current_y=y;
| ^~~~~~~~~
sdl.c:547:3: warning: 'current_x' is static but used in inline function 'LineTo' which is not static
547 | current_x=x;
| ^~~~~~~~~
sdl.c:546:22: warning: 'current_y' is static but used in inline function 'LineTo' which is not static
546 | drawline(current_x,current_y,x,y);
| ^~~~~~~~~
sdl.c:546:12: warning: 'current_x' is static but used in inline function 'LineTo' which is not static
546 | drawline(current_x,current_y,x,y);
But I can not see where the static comes from,
static int is_poly=0;
inline void LineTo(int x,int y)
{
x = convx(x); y = convy(y);
drawline(current_x,current_y,x,y);
current_x=x;
current_y=y;
}