How do I get a working GCC-based C++11 setup on FreeBSD 10? It seems that the standard library that comes with recent GCC versions on FreeBSD is broken. I've installed the port gcc49 and then try to compile this:

    #include <string>
    
    int main()
    {
      auto str = std::to_string(42);
      str = std::to_string(42ull);
      str = std::to_string(4.2);
      str.clear();
      return 0;
    }

This gives me an error:

    g++49 -v -std=c++11 foo.cc
    Using built-in specs.
    COLLECT_GCC=g++49
    COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc49/gcc/x86_64-portbld-freebsd10.0/4.9.2/lto-wrapper
    Target: x86_64-portbld-freebsd10.0
    Configured with: ./../gcc-4.9-20141022/configure --disable-nls --enable-gnu-indirect-function --libdir=/usr/local/lib/gcc49 --libexecdir=/usr/local/libexec/gcc49 --program-suffix=49 --with-as=/usr/local/bin/as --with-gmp=/usr/local --with-gxx-include-dir=/usr/local/lib/gc
    c49/include/c++/ --with-ld=/usr/local/bin/ld --with-pkgversion='FreeBSD Ports Collection' --with-system-zlib --with-ecj-jar=/usr/local/share/java/ecj-4.5.jar --enable-languages=c,c++,objc,fortran,java --prefix=/usr/local --mandir=/usr/local/man --infodir=/usr/local/info/gcc49 --build=x86_64-portbld-freebsd10.0
    Thread model: posix
    gcc version 4.9.2 20141022 (prerelease) (FreeBSD Ports Collection) 
    COLLECT_GCC_OPTIONS='-v' '-std=c++11' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
     /usr/local/libexec/gcc49/gcc/x86_64-portbld-freebsd10.0/4.9.2/cc1plus -quiet -v foo.cc -quiet -dumpbase foo.cc -mtune=generic -march=x86-64 -auxbase foo -std=c++11 -version -o /tmp//ccbNFhtI.s
    GNU C++ (FreeBSD Ports Collection) version 4.9.2 20141022 (prerelease) (x86_64-portbld-freebsd10.0)
            compiled by GNU C version 4.9.2 20141022 (prerelease), GMP version 5.1.3, MPFR version 3.1.2, MPC version 1.0.2
    GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
    ignoring nonexistent directory "/usr/local/lib/gcc49/gcc/x86_64-portbld-freebsd10.0/4.9.2/../../../../../x86_64-portbld-freebsd10.0/include"
    #include "..." search starts here:
    #include <...> search starts here:
     /usr/local/lib/gcc49/include/c++/
     /usr/local/lib/gcc49/include/c++//x86_64-portbld-freebsd10.0
     /usr/local/lib/gcc49/include/c++//backward
     /usr/local/lib/gcc49/gcc/x86_64-portbld-freebsd10.0/4.9.2/include
     /usr/local/include
     /usr/local/lib/gcc49/gcc/x86_64-portbld-freebsd10.0/4.9.2/include-fixed
     /usr/include
    End of search list.
    GNU C++ (FreeBSD Ports Collection) version 4.9.2 20141022 (prerelease) (x86_64-portbld-freebsd10.0)
            compiled by GNU C version 4.9.2 20141022 (prerelease), GMP version 5.1.3, MPFR version 3.1.2, MPC version 1.0.2
    GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
    Compiler executable checksum: 8405316ee381c37148f55a17e42da47a
    foo.cc: In function 'int main()':
    foo.cc:5:14: error: 'to_string' is not a member of 'std'
       auto str = std::to_string(42);
                  ^
    foo.cc:6:9: error: 'to_string' is not a member of 'std'
       str = std::to_string(42ull);
             ^
    foo.cc:7:9: error: 'to_string' is not a member of 'std'
       str = std::to_string(4.2);
             ^

The default include search path is /usr/local/lib/gcc49/include/c++/, which does contain the <string> header. Makes sense, because the gcc49 port ships with a corresponding libstc++. But it seems broken, per the above error.

(Note: I'm aware that Clang is the default compiler on FreeBSD 10. But in this case I'm specifically looking to support a GCC-based toolchain.)