build errors ---so many errors from the source code of variant

[cao1371814]

After cmake --build . it was full of errors, I were only able to post some of them , wondering the clang(libc++) I use is correct or not .
OS ubuntu16.04

[ 2%] Building CXX object P0267_RefImpl/P0267_RefImpl/CMakeFiles/io2d_core.dir/rgba_color.cpp.o
In file included from /home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/xio2d.h:18:0,
from /home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/rgba_color.cpp:1:
/home/cao/workspace/clang+llvm-6.0.0-x86_64-apple-darwin/include/c++/v1/variant: In static member function ‘static constexpr auto std::__1::__variant_detail::__visitation::__base::__make_fdiagonal()’:
/home/cao/workspace/clang+llvm-6.0.0-x86_64-apple-darwin/include/c++/v1/variant:518:67: error: expected ‘,’ before ‘)’ token
static_assert(__all<(_Np == decay_t<_Vs>::__size())...>::value);
^
/home/cao/workspace/clang+llvm-6.0.0-x86_64-apple-darwin/include/c++/v1/variant:518:67: error: expected string-literal before ‘)’ token
/home/cao/workspace/clang+llvm-6.0.0-x86_64-apple-darwin/include/c++/v1/variant: In function ‘constexpr std::__1::variant_alternative_t<_Ip, std::__1::variant<_Types ...> >& std::__1::get(std::__1::variant<_Types ...>&)’:
/home/cao/workspace/clang+llvm-6.0.0-x86_64-apple-darwin/include/c++/v1/variant:1335:40: error: expected ‘,’ before ‘)’ token
static_assert(_Ip < sizeof...(_Types));
^
/home/cao/workspace/clang+llvm-6.0.0-x86_64-apple-darwin/include/c++/v1/variant:1335:40: error: expected string-literal before ‘)’ token
/home/cao/workspace/clang+llvm-6.0.0-x86_64-apple-darwin/include/c++/v1/variant:1336:75: error: expected ‘,’ before ‘)’ token
static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
/home/cao/workspace/clang+llvm-6.0.0-x86_64-apple-darwin/include/c++/v1/variant:1428:32: error: expected string-literal before ‘)’ token
/home/cao/workspace/clang+llvm-6.0.0-x86_64-apple-darwin/include/c++/v1/variant: In function ‘constexpr std::__1::add_pointer_t std::__1::get_if(const std::__1::variant<_Types ...>*)’:
/home/cao/workspace/clang+llvm-6.0.0-x86_64-apple-darwin/include/c++/v1/variant:1436:32: error: expected ‘,’ before ‘)’ token
static_assert(!is_void_v<_Tp>);
/home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/xcolor.h:7:16: note: ‘std::std::experimental::io2d::v1::_Color_is_integral’
In file included from /home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/xio2d.h:144:0,
/home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/rgba_color.cpp:448:27: error: expected ‘}’ at end of input
/home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/rgba_color.cpp:448:27: error: expected ‘}’ at end of input
/home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/rgba_color.cpp:448:27: error: expected ‘}’ at end of input
/home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/rgba_color.cpp:448:27: error: expected ‘}’ at end of input
/home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/rgba_color.cpp:448:27: error: expected ‘}’ at end of input
/home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/rgba_color.cpp:448:27: error: expected ‘}’ at end of input
/home/cao/workspace/P0267_RefImpl/P0267_RefImpl/P0267_RefImpl/rgba_color.cpp:448:27: error: expected ‘}’ at end of input
P0267_RefImpl/P0267_RefImpl/CMakeFiles/io2d_core.dir/build.make:62: recipe for target 'P0267_RefImpl/P0267_RefImpl/CMakeFiles/io2d_core.dir/rgba_color.cpp.o' failed
make[2]: *** [P0267_RefImpl/P0267_RefImpl/CMakeFiles/io2d_core.dir/rgba_color.cpp.o] Error 1
CMakeFiles/Makefile2:104: recipe for target 'P0267_RefImpl/P0267_RefImpl/CMakeFiles/io2d_core.dir/all' failed
make[1]: *** [P0267_RefImpl/P0267_RefImpl/CMakeFiles/io2d_core.dir/all] Error 2
Makefile:140: recipe for target 'all' failed
make: *** [all] Error 2