Linker not always capable of resolving xref in vasm results

[Slamy]

Linker not always capable of resolving xref in vasm results

[BartmanAbyss]

This is just a side-effect of LTO/-fwhole-program: (see also [https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html])
Just put __attribute__((externally_visible)) in front of void HerpDerp() and it will work fine. However be careful and read the link above to avoid any strange duplication behavior.

[Slamy]

This solved the issue and I do have to admit that I wasn't aware of the effect of '-fwhole-program'. Still two things bother me:

1. How can we avoid having people fall into the same trap? It will happen eventually.
2. Why is the effect not observable via 'm68k-amiga-elf-objdump'? I would have understood the whole problem if the symbol was absent from the object file. Still this isn't the case. Maybe I'm missing the whole picture. I'm by far no compiler/linker expert.

[BartmanAbyss]

1. I thought about that as well, but I'm not sure.. This was the first time this ever came up.
2. Thing is, with LTO the object files aren't standard. They contain only intermediate code representation. The actual compiling is done during the linking step. This is what enables the huge benefits of LTO (project-wide code visibility for inlining, optimizing, etc.)