Finding mangled C++ link error - c++

Question

There are two link errors in this project.
The first, pointed out by #Steve, is the lack of
void *__gxx_personality_v0;
If anyone can explain why a C++ project compiled with clang++3.5 under cygwin would create a reference to this, I would like to understand. Anyway, I defined the symbol as a workaround.
The other problem appears to be references to 32-bit relative addressing in 64-bit. I am looking for a way to tell clang++ to compile 32 bit or 64 bit. I will try on native linux as well, but again, if anyone can explain why this is happening, I would like to understand.
I am thinking it might be a static variable, located down low in the address space, being accessed by something on the stack, but again, clang is generating everything so as far as I can see, this is a bug in the compiler.
clang++ -std=c++11 -O2 -g -I include/ -pthread -c RequestHandler.cc
clang++ -std=c++11 -O2 -g Config.o Logger.o RequestHandler.o FileSys.\
o Buffer.o server.o CspServlet.o -pthread -o server
RequestHandler.o:fake:(.debug_info+0x54bd): relocation truncated to f\
it: R_X86_64_32 against `.debug_ranges'
...
FileSys.o:fake:(.eh_frame$_ZNSt10_HashtableISsSt4pairIKSsP2FLESaIS4_E\
NSt8__detail10_Select1stESt8equal_toISsESt4hashISsENS6_18_Mod_range_h\
ashingENS6_20_Default_ranged_hashENS6_20_Prime_rehash_policyENS6_17_H\
ashtable_traitsILb1ELb0ELb1EEEE21_M_insert_unique_nodeEmmPNS6_10_Hash\
_nodeIS4_Lb1EEE+0x13): undefined reference to `__gxx_personality_v0'
FileSys.o:fake:(.eh_frame$_ZNSt8__detail16_Hashtable_allocISaINS_10_H\
ash_nodeISt4pairIKSsP2FLELb1EEEEE16_M_allocate_nodeIJRKS6_EEEPS7_DpOT\
_+0x13): more undefined references to `__gxx_personality_v0' follow
collect2: error: ld returned 1 exit status

Answer 1

Ok, it turns out that on cygwin, when I installed clang, it doesn't fully use the clang toolchain. clang is compiling, but g++ is linking (I think). Bear in mind all these tools could be aliased to something else, but it's very suspicious.
I built on Unix and it worked. Same makefile.
So the problem is that when I wrote clang, it wasn't using clang to link. And that is weird.