Undefined Reference Error When Linking to Static Library

Question

I am trying to compile a project that depends on the Xerces XML Parser. The project compiles for Windows without any difficulty, but I'm having some trouble compiling it with g++ in Cygwin.

In order to use Xerces, I am trying to compile my code against the static library libxerces-c.a. But when I do so, I get errors that look like this:

/tmp/cc2QGvMh.o:test.cpp:(.text+0x3a): undefined reference to `xercesc_2_8::DOMImplementationRegistry::getDOMImplementation(unsigned short const*)'

I've inspected the static library using ar, and confirmed that it contains the DOMImplementationRegistry.o file that defines the function that I am calling.

ar -t libxerces-c.a
...
DOMImplementationImpl.o
DOMImplementationRegistry.o
DOMLocatorImpl.o
...

I've also extracted the object files from the library, and used 'nm' to make sure that the function I am calling actually exists:

ar -x libxerces-c.a
nm --demangle DOMImplementationRegistry.o
...
00000080 T xercesc_2_8::getDOMImplSrcVectorMutex()
00000300 T xercesc_2_8::DOMImplementationRegistry::getDOMImplementation(unsigned short const*)
000002a0 T xercesc_2_8::DOMImplementationRegistry::addSource(xercesc_2_8::DOMImplementationSource*)
...

Since I can compile everything for Windows but not with g++, I thought that the error could be in the linker order (similar to the problem described in this question). However, even after changing the linker order, I am still getting the same compiler error. I have tried both

g++ -o test.exe test.cpp -Llib -lxerces-c

and

g++ -o test.exe test.cpp lib/libxerces-c.a

Any ideas?

Answer 1

Your project uses method from xercesc_2_6 namespace as pointed by compiler error message but your library offers xercesc_2_8 version. Problem is probably caused by mismatch between headers you use and library object file.