Answer by user9876 for How to remove this warning: second parameter of ‘va_start’ not last named argument?

second parameter of ‘va_start’ not last named argument

What does it means and how to remove it?

Your function has named parameters parent, fmt and size. The C spec says you have to always pass the last named parameter to va_start, for compatibility with older compilers. So you must pass size, not fmt.

(But with a modern compiler, it might work anyway)