Ubuntu下安装g++ 4.9.0（实验）版本（我正在使用该版本提供的某些功能）
在构建我的代码时，我cmake从脚本中使用它，并且它可以正确构建。下面的gcc包含安装 g++ 的路径（/mnt...）
$_cmake_ $_dir_ -DCMAKE_CXX_COMPILER=${_gpp_} -DCMAKE_C_COMPILER=${_gcc_} -DCMAKE_BUILD_TYPE=${_build_} -DCMAKE_INSTALL_PREFIX=${_install_} -DBUILD_TESTING:BOOL=1
现在，当我让 CppuTest 为我的代码构建单元测试时，我收到以下错误。
make all
compiling UncrosserTest.cpp
In file included from /home/miguel/Desktop/Ugur/scmProject/scm/dist/dev/mfx_prod/scm/20160207/include/scm/services/primitives.hpp:4:0,
from /home/miguel/Desktop/Ugur/scmProject/log/lidya/src/cpp/scm/services/examples/dummy_strategy/Inside.hpp:6,
from AllTests/Uncrosser/UncrosserTest.cpp:7:
/usr/include/c++/4.9/experimental/optional: In member function ‘void std::experimental::_Optional_base<_Tp, _ShouldProvideDestructor>::_M_construct(_Args&& ...)’:
/usr/include/c++/4.9/experimental/optional:294:18: error: expected type-specifier
::new (std::__addressof(this->_M_payload))
^
/usr/include/c++/4.9/experimental/optional:294:18: error: expected ‘)’
/usr/include/c++/4.9/experimental/optional: In member function ‘void std::experimental::_Optional_base<_Tp, false>::_M_construct(_Args&& ...)’:
/usr/include/c++/4.9/experimental/optional:424:18: error: expected type-specifier
::new (std::__addressof(this->_M_payload))
^
/usr/include/c++/4.9/experimental/optional:424:18: error: expected ‘)’
make: *** [objs/AllTests/Uncrosser/UncrosserTest.o] Error 1
在 CppuTest makefile 中包含了CPPUTEST_CPPFLAGS += -std=c++1y. 我想这在这个 makefile 中缺少一些标志，因为正如我所说，C++ 实验库正在我的“常规”代码中正确构建。我错过了什么？