CMake for an Xcode target vs. a normal target - xcode

Question

I have this simple C++11 code.
#include <vector>
#include <iostream>
#include <memory>
using namespace std;
class A
{
int x;
public:
A() {}
~A() {}
A(A& a) {}
A(int x) {this->x = x;}
int get() {return x;}
};
int main()
{
vector<unique_ptr<A>> v;
auto a = new A(10);
unique_ptr<A> pa(a);
v.push_back(move(pa)); // move(pa);
auto a2 = new A(20);
unique_ptr<A> pb(a2);
v.push_back(move(pb)); // move(pa);
for (auto& i: v)
{
cout << i->get();
}
}
I'm trying to build this code with a CMake setup on Xcode and clang++.
This is the CMakeLists.txt file:
cmake_minimum_required(VERSION 2.8)
project( testit )
set(CMAKE_CXX_FLAGS "-std=c++11 -stdlib=libc++")
set(testit
testit.cpp
)
add_executable(gv ${testit})
clang++ build.
mkdir build and cd build
export CC=/usr/bin/clang
export CXX=/usr/bin/clang++
cmake ..
make
I could get the binary that works fine.
Xcode 4.5 target
Same step 1-3
cmake .. -G Xcode
xcodebuild
Compilation works fine, but I got an error in the build with Undefined symbol error.
I setup C++11 with this command in CMake set(CMAKE_CXX_FLAGS "-std=c++11 -stdlib=libc++").
Undefined symbols for architecture x86_64:
"std::__1::__vector_base_common<true>::__throw_length_error() const", referenced from:
void std::__1::vector<std::__1::unique_ptr<A, std::__1::default_delete<A> >, std::__1::allocator<std::__1::unique_ptr<A, std::__1::default_delete<A> > > >::__push_back_slow_path<std::__1::unique_ptr<A, std::__1::default_delete<A> > >(std::__1::unique_ptr<A, std::__1::default_delete<A> >&&) in testit.o
"std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(int)", referenced from:
_main in testit.o
"std::__1::cout", referenced from:
_main in testit.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
What might be wrong?
ADDED
From this link, it seems that the target setup is wrong with the xbuildcode from CMake:
http://www.executionunit.com/blog/2012/10/27/xcode-std-link-errors/
ADDED
I could fix this issue, but I had to use the same directory where the CMakeLists.txt file is located.
When I execute CMake .. -G XCode I got another error.
=== BUILD AGGREGATE TARGET ZERO_CHECK OF PROJECT XcodeTest WITH THE DEFAULT CONFIGURATION (Debug) ===
Check dependencies
PhaseScriptExecution "CMake Rules" build/XcodeTest.build/Debug/ZERO_CHECK.build/Script-BED7FB205C634C34A1ACD293.sh
cd /Users/smcho/Desktop/cmake
/bin/sh -c /Users/smcho/Desktop/cmake/build/XcodeTest.build/Debug/ZERO_CHECK.build/Script-BED7FB205C634C34A1ACD293.sh
echo ""
make -f /Users/smcho/Desktop/cmake/build/CMakeScripts/ReRunCMake.make
make[1]: *** No rule to make target `/Users/smcho/Desktop/cmake/build/CMakeFiles/2.8.10.2/CMakeCCompiler.cmake', needed by `CMakeFiles/cmake.check_cache'. Stop.
make: *** [/Users/smcho/Desktop/cmake/build/CMakeFiles/ZERO_CHECK] Error 2
Command /bin/sh failed with exit code 2
** BUILD FAILED **
The following build commands failed:
PhaseScriptExecution "CMake Rules" build/XcodeTest.build/Debug/ZERO_CHECK.build/Script-BED7FB205C634C34A1ACD293.sh

Answer 1

There were two issues.
Linker option
As Fraser pointed out, the issue was from setup in the linker.
...
set(CMAKE_CXX_FLAGS "-std=c++11 -stdlib=libc++")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -stdlib=libc++")
...
Add_subdirectory
I'm not sure why is this for, but I needed to use add_subdirectory(src) in the main CMakeLists.txt file, and make another CMakeLists.txt file in that src directory in order to run CMake in the build directory. Without it, I had to run CMake in the same directory where the CMakeLists.txt file is located. See Stack Overflow question CMake Xcode generator creates a project that cannot build
This is the CMakeLists.txt in the src directory:
set(CMAKE_CXX_FLAGS "-std=c++11 -stdlib=libc++")
file ( GLOB SRCS *.cpp )
add_executable( program ${SRCS})
This is the CMakeLists.txt in the main directory:
project( XcodeTest )
cmake_minimum_required( VERSION 2.6 )
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -stdlib=libc++")
add_subdirectory(src)
I got the hint from this YouTube video: CMake XCode Demo