Even specifying `eh_unwind_resume` as a lang item gives me a linking error in debug builds.
Did you define them exactly the same way? Every aspect has to be identical; extern, no mangle, function name, arguments, lang item.
If this happens to be open source, I can take a look at it.
I just whipped this up yesterday to test if I was still having the same issues. Debug fails to build with a linking error "undefined reference to `_Unwind_Resume`". Release build works fine.
This didn't fix the compilation errors for me. I can set my own no_mangle pub extern `_Unwind_Resume` function (without declaring it a lang_item) and fix the undefined reference that way, but I'm pretty sure that's not how one's supposed to solve this
Hm, it compiled for me. Well, it didn't know about the C functions that were being linked in, but it didn't complain about the lang items.