Function ion_c_sys::ion_writer_write_field_name

pub unsafe extern "C" fn ion_writer_write_field_name(
    hwriter: hWRITER, 
    name: iSTRING
) -> iERR

Sets the writer’s current field name. Only valid if the writer is currently in a struct. It is the caller’s responsibility to keep name in scope until the writer’s next value is written.