Xcode build error

[ProjectQuantumofficial]

I have this problem what can I do ?
/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/bitmap_font.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/bitmap_font.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/common/videolink/vfilters/catrom3x.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/common/videolink/vfilters/catrom3x.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/sound/envelope_unit.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/sound/envelope_unit.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/initstate.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/initstate.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/video/lyc_irq.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/video/lyc_irq.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/common/videolink/vfilters/maxsthq2x.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/common/videolink/vfilters/maxsthq2x.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/common/resample/src/resamplerinfo.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/common/resample/src/resamplerinfo.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/common/skipsched.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/common/skipsched.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/sound.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/sound.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/video/sprite_mapper.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/video/sprite_mapper.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/state_osd_elements.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/state_osd_elements.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/statesaver.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/statesaver.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/tima.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/tima.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/common/resample/src/u48div.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/common/resample/src/u48div.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/common/videolink/vfilterinfo.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/common/videolink/vfilterinfo.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?

/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/video.cpp Build input file cannot be found: '/Users/famille/Downloads/GIOVANNI-master/gambatte/libgambatte/src/video.cpp'. Did you forget to declare this file as an output of a script phase or custom build rule which produces it?