linker script hack - can it be made to work ?

Im attempting to conditionally link an input section. if the just linked similarly named section wasnt empty. __start___dyndbg = .; \ _ = .; \ \ KEEP(*(__dyndbg (.-_)? gnu.linkonce.d.__dyndbg)) \ __stop___dyndbg = .; it gives me an unspecified linker syntax error ld:./arch/x86/kernel/vmlinux.lds:46: syntax error its pretty clear that this experiment is failing, is there another way to do this ?