title: ld: symbol(s) not found for architecture x86_64 using GNU Make and clang
body: <p>I am getting a <code>ld: symbol(s) not found for architecture x86_64</code> error. I did do a thorough search through previous threads, but did not find a solution.</p>
  
  <p>As a test I am compiling a program test.cpp:</p>
  
  <pre><code>#include &lt;iostream&gt;
  
  using namespace std;
  
  int main(){
   return 0;
  }
  </code></pre>
  
  <p>with the Makefile:</p>
  
  <pre><code>CXX=g++
  CXXFLAGS=-g -Wall -W -Wconversion -Wshadow -Wcast-qual -Wwrite-strings $(shell root-config --cflags --glibs)
  CPPFLAGS+=-MMD -MP
  LDFLAGS=-g $(shell root-config --ldflags)
  LDLIBS=$(shell root-config --libs)
  
  test.o: test.cpp
  
  test: test.o
  -include test.d
  </code></pre>
  
  <p>Running <code>make test</code> in my linux computer produces the following correct output:</p>
  
  <pre><code>CAM ~/Wenu $ make test
  g++ -g -Wall -W -Wconversion -Wshadow -Wcast-qual -Wwrite-strings -pthread -m64 -I/cvmfs/lhcb.cern.ch/lib/RootConfig/pro/x86_64-slc5-gcc46-opt/root/include -L/cvmfs/lhcb.cern.ch/lib/RootConfig/pro/x86_64-slc5-gcc46-opt/root/lib -lGui -lCore -lCint -lRIO -lNet -lHist -lGraf -lGraf3d -lGpad -lTree -lRint -lPostscript -lMatrix -lPhysics -lMathCore -lThread -pthread -lm -ldl -rdynamic -MMD -MP  -c -o test.o test.cpp
  cc -g -m64  test.o  -L/cvmfs/lhcb.cern.ch/lib/RootConfig/pro/x86_64-slc5-gcc46-opt/root/lib -lCore -lCint -lRIO -lNet -lHist -lGraf -lGraf3d -lGpad -lTree -lRint -lPostscript -lMatrix -lPhysics -lMathCore -lThread -pthread -lm -ldl -rdynamic -o test
  CAM ~/Wenu $
  </code></pre>
  
  <p>Compiling it on my Mac fails in the linking stage with a <code>ld: symbol(s) not found for architecture x86_64</code> error:</p>
  
  <pre><code>MAC ~/Transmit/Wenu $ make test
  g++ -g -Wall -W -Wconversion -Wshadow -Wcast-qual -Wwrite-strings -pthread -m64 -I/opt/local/root-v5-34-00/include -L/opt/local/root-v5-34-00/lib -lGui -lCore -lCint -lRIO -lNet -lHist -lGraf -lGraf3d -lGpad -lTree -lRint -lPostscript -lMatrix -lPhysics -lMathCore -lThread -lpthread -Wl,-rpath,/opt/local/root-v5-34-00/lib -lm -ldl -MMD -MP  -c -o test.o test.cpp
  i686-apple-darwin11-llvm-g++-4.2: -lGui: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lCore: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lCint: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lRIO: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lNet: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lHist: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lGraf: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lGraf3d: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lGpad: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lTree: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lRint: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lPostscript: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lMatrix: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lPhysics: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lMathCore: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lThread: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lpthread: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -rpath: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: /opt/local/root-v5-34-00/lib: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -lm: linker input file unused because linking not done
  i686-apple-darwin11-llvm-g++-4.2: -ldl: linker input file unused because linking not done
  cc -g -m64  test.o  -L/opt/local/root-v5-34-00/lib -lCore -lCint -lRIO -lNet -lHist -lGraf -lGraf3d -lGpad -lTree -lRint -lPostscript -lMatrix -lPhysics -lMathCore -lThread -lpthread -Wl,-rpath,/opt/local/root-v5-34-00/lib -lm -ldl -o test
  Undefined symbols for architecture x86_64:
    "std::ios_base::Init::Init()", referenced from:
        __static_initialization_and_destruction_0(int, int) in test.o
    "std::ios_base::Init::~Init()", referenced from:
        ___tcf_0 in test.o
  ld: symbol(s) not found for architecture x86_64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  make: *** [test] Error 1
  </code></pre>
  
  <p>Any help would be very appreciated.</p>
  
  <p>In case any of this is relevant, I have a 64-bit Mac with OS X 10.7.5 and I have a compiler that came with XCode's command line tools:</p>
  
  <pre><code>MAC ~/Transmit/Wenu $ clang --version
  Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
  Target: x86_64-apple-darwin11.4.2
  Thread model: posix
  </code></pre>
  
  <p>ROOT is a collection of C++ libraries that I use in my programs.</p>