I'm analyzing vfprintf performance, I don't know why musl call "printf_core(0, fmt, &ap2, nl_arg, nl_type)" here. Could you tell me the reason?

https://gitee.com/openharmony/third_party_musl/blob/master/src/stdio/vfprintf.c#L668

More info:

    I use gdb to debug vfprintf , I found it return directly when calling printf_core firstly which file parameter is 0.

https://gitee.com/openharmony/third_party_musl/blob/master/src/stdio/vfprintf.c#L526

Best Regards

Chuang Yin