The user then compiled with Clang and caught a link error.
clang can't handle abi tags (i.e. can't link to new-ABI code even if you aren't trying to mix it with old-ABI code):
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=797917 https://llvm.org/bugs/show_bug.cgi?id=23529