Cannot compile with Apple LLVM version 9.1.0 (clang-902.0.39.1) about bustache HOT 2 CLOSED

struct S {
    std::function<S()> f;
};

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/__config:441:15: note: expanded from macro '_VSTD'
#define _VSTD std::_LIBCPP_NAMESPACE
              ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/type_traits:4220:23: note: expanded from macro '_LIBCPP_INVOKE_RETURN'
    noexcept(noexcept(__VA_ARGS__)) -> decltype(__VA_ARGS__) \
                      ^~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/type_traits:4340:9: note: in instantiation of exception specification for '__invoke<std::__1::function<S ()> &>' requested here
        _VSTD::__invoke(_VSTD::declval<_Fp>(), _VSTD::declval<_Args>()...));
        ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/__config:441:15: note: expanded from macro '_VSTD'
#define _VSTD std::_LIBCPP_NAMESPACE
              ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/functional:1601:33: note: in instantiation of template class 'std::__1::__invokable_r<void, std::__1::function<S ()> &>' requested here
                                __invokable<_Fp&, _ArgTypes...>::value>
                                ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/functional:1626:9: note: in instantiation of default argument for '__callable<std::__1::function<S ()> >' required here
        __callable<_Fp>::value && !is_same<_Fp, function>::value
        ^~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/functional:1628:5: note: in instantiation of default argument for 'function<std::__1::function<S ()> >' required here
    function(_Fp);
    ^~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/functional:1588:28: note: while substituting deduced template arguments into function template 'function' [with _Fp = std::__1::function<S ()>, $1 = (no value)]
class _LIBCPP_TEMPLATE_VIS function<_Rp(_ArgTypes...)>
                           ^
/Users/build/main.cpp:13:8: note: while declaring the implicit move constructor for 'S'
struct S {
       ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/functional:1680:9: note: 'operator()' declared here
    _Rp operator()(_ArgTypes...) const;
        ^
/Users/build/mrep/rep/Flow/FlowServer/main.cpp:13:8: note: definition of 'S' is not complete until the closing '}'
struct S {
       ^
1 error generated.`