cmake link error in stringpiece

[dzhwinter]

when it compile the stringpiece, compiler goes in wrong way of using the gcc instead of g++.

Undefined symbols for architecture x86_64:
  "std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::operator<<<char, std::__1::char_traits<char>, std::__1::allocator<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)", referenced
 from:
      paddle::operator<<(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, paddle::StringPiece) in libstringpiece.a(stringpiece.cc.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[2]: *** [paddle/strings/stringpiece_test] Error 1
make[1]: *** [paddle/strings/CMakeFiles/stringpiece_test.dir/all] Error 2
make: *** [all] Error 2

[gangliao]

I did not get this error on my computer.

[gangliao]

[ 85%] Linking CXX executable stringpiece_test
cd /Users/liaogang/baidu/Paddle/build/paddle/strings && /usr/local/Cellar/cmake/3.7.1/
bin/cmake -E cmake_link_script CMakeFiles/stringpiece_test.dir/link.txt --verbose=1
/usr/local/bin/ccache /Library/Developer/CommandLineTools/usr/bin/c++    -std=c++11 -f
PIC -fno-omit-frame-pointer -Wall -Wextra -Werror -Wnon-virtual-dtor -Wdelete-non-virt
ual-dtor -Wno-unused-parameter -Wno-unused-function -Wno-error=sign-compare -Wno-error
=unused-local-typedefs -mavx -O2 -g -DNDEBUG -arch x86_64 -Wl,-search_paths_first -Wl,
-headerpad_max_install_names  CMakeFiles/stringpiece_test.dir/stringpiece_test.cc.o  -
o stringpiece_test  libstringpiece.a ../../../third_party/install/glog/lib/libglog.a .
./../../third_party/install/gflags/lib/libgflags.a ../../../third_party/install/gtest/
lib/libgtest.a ../../../third_party/install/gtest/lib/libgtest_main.a
Undefined symbols for architecture x86_64:
  "std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::operator<<<c
har, std::__1::char_traits<char>, std::__1::allocator<char> >(std::__1::basic_ostream<
char, std::__1::char_traits<char> >&, std::__1::basic_string<char, std::__1::char_trai
ts<char>, std::__1::allocator<char> > const&)", referenced from:
      paddle::operator<<(std::__1::basic_ostream<char, std::__1::char_traits<char> >&,
 paddle::StringPiece) in libstringpiece.a(stringpiece.cc.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[3]: *** [paddle/strings/stringpiece_test] Error 1
make[2]: *** [paddle/strings/CMakeFiles/stringpiece_test.dir/all] Error 2
make[1]: *** [paddle/strings/CMakeFiles/stringpiece_test.dir/rule] Error 2
make: *** [stringpiece_test] Error 2

Same problem on my machine. I think it only happens on Mac OS X. @cxwangyi @wangkuiyi