We have some code that compile fine on Mac OS X with g++ using makefiles, but I cannot build successfully with Xcode.
Here is the brief overview of the project setup, there are instances of the following:
libA.a
- contains myclass_stub.cpp which implements func()
- Our makefiles would package the library with 'ar -r', which allows replacement of existing methods.
- Xcode would use libtool to package it
program.exe contains myclass.cpp which implements func() as well. and links libA.a statically using g++
If I were to build libA.a and program.exe with Xcode, it complains about "Duplicate symbol" func in myclass_stub.o and myclass.o at link time.
I also tried compiling program.exe with Xcode, and linking it against libA.a that was packaged with 'ar -r', but it stills complains about duplicate symbol.
Having duplicate implementation might not be ideal, but I cannot get around it at the moment. If I could get the code to build with makefiles using standard 'ar' and 'g++', I would like to know what options I need to set in Xcode for it to work.
Now, my questions:
I would like to use 'ar -r' to package the library in Xcode instead. Is it possible? If so, how? Is there a similar option with libtool where I can force replacement of existing symbols?
I suppose the difference between libtool and 'ar -r' might not be the main difference between building with Xcode and with makefiles. I do have the same compiler flags, but the list of input/object files is mostly likely in a different order. Do you see any other possible solutions to this linking error?
I saw a related to question @ libtool vs ar for creating a static library (xcode linker), but not the solution
By the way, I also tried adding all-load and --force-load, but they don't seem to do much since I am just trying to build for x86_64.
I don't know anything about xcode, but have you thought about using weak symbols (in g++ : attribute((weak))) for symbols that should be overridden ?