Function CxLABEL_len_flags 

pub unsafe fn CxLABEL_len_flags(
    my_perl: *mut PerlInterpreter,
    c: *const PERL_CONTEXT,
    len: *mut STRLEN,
    flags: *mut U32,
) -> *const c_char

CxLABEL_len_flags [THX] - macro function