Assertion failure in 2.18

[Yang]

I'm getting the following error:

as: BFD (GNU Binutils for Ubuntu) 2.18 assertion fail ../../bfd/elf.c:6239
as: BFD (GNU Binutils for Ubuntu) 2.18 internal error, aborting at 
../../bfd/elfcode.h line 221 in bfd_elf64_swap_symbol_out

This only happens when I build with no -O3; once I specify -O3, this 
seems to go away. I'm just jumping into a moderately sized codebase for 
an OS kernel with no kernel hacking experience, so it would take me some 
time to debug this. Any ideas what this is caused by? Thanks in advance.