XCode 9.3升级或替换libc++； 我有C++的代码，它在GCC、MSVC2015、Android NDK、……上都非常完美。p> class JsonLongText { private: enum JsonToken { JT_OBJECT, JT_ARRAY, JT_VARIABLE, JT_EMPTY }; typedef std::vector<JsonToken> JsonTokenStack; JsonTokenStack m_OpenTokens; .... JsonLongText() : m_IgnoreEmptyItems(true), m_RequireItemSeparator(false), m_PrettyPrint(false) {} }

原因：

In file included from Expression.cpp:113:
In file included from ./StdAfx.h:23:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/algorithm:643:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2051:9: error: cannot initialize a member subobject
      of type 'std::__1::sub_match<const char *> *' with an rvalue of type 'long'
      : __value_(_VSTD::forward<_Up>(__u)){};
        ^        ~~~~~~~~~~~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2151:9: note: in instantiation of function template
      specialization 'std::__1::__compressed_pair_elem<std::__1::sub_match<const char *> *, 0, false>::__compressed_pair_elem<long, void>' requested here
      : _Base1(std::forward<_U1>(__t1)), _Base2(std::forward<_U2>(__t2)) {}
        ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:432:7: note: in instantiation of function template
      specialization 'std::__1::__compressed_pair<std::__1::sub_match<const char *> *, std::__1::allocator<std::__1::sub_match<const char *> >
      >::__compressed_pair<long, const std::__1::allocator<std::__1::sub_match<const char *> > &>' requested here
      __end_cap_(nullptr, __a)
      ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:485:11: note: in instantiation of member function
      'std::__1::__vector_base<std::__1::sub_match<const char *>, std::__1::allocator<std::__1::sub_match<const char *> > >::__vector_base' requested here
        : __base(__a)
          ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:5355:7: note: in instantiation of member function
      'std::__1::vector<std::__1::sub_match<const char *>, std::__1::allocator<std::__1::sub_match<const char *> > >::vector' requested here
    : __matches_(__a),
      ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2988:34: note: in instantiation of member function
      'std::__1::match_results<const char *, std::__1::allocator<std::__1::sub_match<const char *> > >::match_results' requested here
    match_results<const _CharT*> __m;
                                 ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2978:5: note: (skipping 4 contexts in backtrace; use
      -ftemplate-backtrace-limit=0 to see all)
    __lookahead(const basic_regex<_CharT, _Traits>& __exp, bool __invert, __node<_CharT>* __s, unsigned __mexp)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4098:35: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_term<const char *>' requested here
        _ForwardIterator __temp = __parse_term(__first, __last);
                                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4074:31: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_alternative<const char *>' requested here
    _ForwardIterator __temp = __parse_alternative(__first, __last);
                              ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:3026:19: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_ecma_exp<const char *>' requested here
        __first = __parse_ecma_exp(__first, __last);
                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2522:10: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse<const char *>' requested here
        {__parse(__p, __p + __traits_.length(__p));}
         ^
Expression.cpp:3356:16: note: in instantiation of member function 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::basic_regex' requested here
    std::regex txt_regex("[a-z]+\\.txt");
               ^
In file included from Expression.cpp:113:
In file included from ./StdAfx.h:23:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/algorithm:643:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2051:9: error: cannot initialize a member subobject
      of type 'std::__1::__state<char> *' with an rvalue of type 'long'
      : __value_(_VSTD::forward<_Up>(__u)){};
        ^        ~~~~~~~~~~~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2141:9: note: in instantiation of function template
      specialization 'std::__1::__compressed_pair_elem<std::__1::__state<char> *, 0, false>::__compressed_pair_elem<long, void>' requested here
      : _Base1(std::forward<_Tp>(__t)), _Base2() {}
        ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:423:7: note: in instantiation of function template
      specialization 'std::__1::__compressed_pair<std::__1::__state<char> *, std::__1::allocator<std::__1::__state<char> > >::__compressed_pair<long, true>'
      requested here
      __end_cap_(nullptr)
      ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:473:5: note: in instantiation of member function
      'std::__1::__vector_base<std::__1::__state<char>, std::__1::allocator<std::__1::__state<char> > >::__vector_base' requested here
    vector() _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:5536:21: note: in instantiation of member function
      'std::__1::vector<std::__1::__state<char>, std::__1::allocator<std::__1::__state<char> > >::vector' requested here
    vector<__state> __states;
                    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2990:29: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__match_at_start_ecma<std::__1::allocator<std::__1::sub_match<const char *>
      > >' requested here
    bool __matched = __exp_.__match_at_start_ecma(
                            ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2978:5: note: (skipping 4 contexts in backtrace; use
      -ftemplate-backtrace-limit=0 to see all)
    __lookahead(const basic_regex<_CharT, _Traits>& __exp, bool __invert, __node<_CharT>* __s, unsigned __mexp)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4098:35: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_term<const char *>' requested here
        _ForwardIterator __temp = __parse_term(__first, __last);
                                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4074:31: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_alternative<const char *>' requested here
    _ForwardIterator __temp = __parse_alternative(__first, __last);
                              ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:3026:19: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_ecma_exp<const char *>' requested here
        __first = __parse_ecma_exp(__first, __last);
                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2522:10: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse<const char *>' requested here
        {__parse(__p, __p + __traits_.length(__p));}
         ^
Expression.cpp:3356:16: note: in instantiation of member function 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::basic_regex' requested here
    std::regex txt_regex("[a-z]+\\.txt");
               ^
In file included from Expression.cpp:113:
In file included from ./StdAfx.h:23:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/algorithm:643:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2141:9: error: no matching constructor for
      initialization of '__compressed_pair_elem<std::__1::sub_match<const char *> *, 0>'
      : _Base1(std::forward<_Tp>(__t)), _Base2() {}
        ^      ~~~~~~~~~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:423:7: note: in instantiation of function template
      specialization 'std::__1::__compressed_pair<std::__1::sub_match<const char *> *, std::__1::allocator<std::__1::sub_match<const char *> >
      >::__compressed_pair<long, true>' requested here
      __end_cap_(nullptr)
      ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:473:5: note: in instantiation of member function
      'std::__1::__vector_base<std::__1::sub_match<const char *>, std::__1::allocator<std::__1::sub_match<const char *> > >::__vector_base' requested here
    vector() _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:1326:5: note: in instantiation of member function
      'std::__1::vector<std::__1::sub_match<const char *>, std::__1::allocator<std::__1::sub_match<const char *> > >::vector' requested here
    __state()
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:5545:28: note: in instantiation of member function
      'std::__1::__state<char>::__state' requested here
        __states.push_back(__state());
                           ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2990:29: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__match_at_start_ecma<std::__1::allocator<std::__1::sub_match<const char *>
      > >' requested here
    bool __matched = __exp_.__match_at_start_ecma(
                            ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2978:5: note: (skipping 4 contexts in backtrace; use
      -ftemplate-backtrace-limit=0 to see all)
    __lookahead(const basic_regex<_CharT, _Traits>& __exp, bool __invert, __node<_CharT>* __s, unsigned __mexp)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4098:35: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_term<const char *>' requested here
        _ForwardIterator __temp = __parse_term(__first, __last);
                                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4074:31: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_alternative<const char *>' requested here
    _ForwardIterator __temp = __parse_alternative(__first, __last);
                              ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:3026:19: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_ecma_exp<const char *>' requested here
        __first = __parse_ecma_exp(__first, __last);
                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2522:10: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse<const char *>' requested here
        {__parse(__p, __p + __traits_.length(__p));}
         ^
Expression.cpp:3356:16: note: in instantiation of member function 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::basic_regex' requested here
    std::regex txt_regex("[a-z]+\\.txt");
               ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2037:8: note: candidate constructor
      (the implicit copy constructor) not viable: no known conversion from 'long' to 'const std::__1::__compressed_pair_elem<std::__1::sub_match<const char
      *> *, 0, false>' for 1st argument
struct __compressed_pair_elem {
       ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2037:8: note: candidate constructor
      (the implicit move constructor) not viable: no known conversion from 'long' to 'std::__1::__compressed_pair_elem<std::__1::sub_match<const char *> *,
      0, false>' for 1st argument
struct __compressed_pair_elem {
       ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2050:3: note: candidate template ignored:
      substitution failure [with _Up = long, $1 = void]
  __compressed_pair_elem(_Up&& __u)
  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2055:3: note: candidate constructor template not
      viable: requires 3 arguments, but 1 was provided
  __compressed_pair_elem(piecewise_construct_t, tuple<_Args...> __args,
  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2043:39: note: candidate constructor not viable:
      requires 0 arguments, but 1 was provided
  _LIBCPP_INLINE_VISIBILITY constexpr __compressed_pair_elem() : __value_() {}

包含在表达式中的文件中。cpp:113：
在包含于./StdAfx.h:23的文件中：
在/Applications/Xcode.app/Contents/Developer/Toolchains/xcodefault.xctoolchain/usr/include/c++/v1/algorithm:643中包含的文件中：
/Applications/Xcode.app/Contents/Developer/toolschains/xcodefault.xctoolschain/usr/include/c++/v1/memory:2051:9:错误：无法初始化成员子对象
类型为“std:：_1:：sub_match*”且右值类型为“long”
：u值_u（VSTD:：forward（u））{}；
^        ~~~~~~~~~~~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2151:9:注意：在函数模板的实例化中
专门化'std:：uuuu 1:：uuu compressed\u pair\u elem:：uu compressed\u pair\u elem'已在此处请求
：_Base1（std:：forward（_t1）），_Base2（std:：forward（_t2））{
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:432:7:注意：在函数模板的实例化中
此处请求的专用化“std:：uuu 1:：uu compressed_pair:：u compressed_pair”
__端盖（空端，a）
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:485:11:注意：在成员函数的实例化中
“std:：uuuu 1:：uuu vector_base:：uu vector_base”已在此处请求
：uu基（u a）
^
/Applications/Xcode.app/Contents/Developer/toolschains/xcodefault.xctoolschain/usr/include/c++/v1/regex:5355:7:注意：在成员函数的实例化中
此处请求了“std:：_1:：vector:：vector”
：uu匹配uu（uu a），
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2988:34:注意：在成员函数的实例化中
此处请求的“std:：：\u 1:：match\u results:：match\u results”
匹配结果；
^
/Applications/Xcode.app/Contents/Developer/toolschains/XcodeDefault.xctoolschain/usr/include/c++/v1/regex:2978:5:注意：（在回溯中跳过4个上下文；使用
-ftemplate backtrace limit=0以查看所有内容）
__前瞻（常量基本正则表达式和表达式，布尔倒转，节点*，无符号mexp）
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4098:35:注意：在函数模板的实例化中
此处请求专门化“std:：_u1:：basic_regex:：_parse_term”
_ForwardIterator uuu temp=uuuu parse_term（uuu first，uuu last）；
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4074:31:注意：在函数模板的实例化中
此处请求专门化“std:：_u1:：basic_regex:：_parse_alternative”
_ForwardIterator uuu temp=uuuu parse_alternative（uuu first，uuu last）；
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:3026:19：注意：在函数模板的实例化中
此处请求专门化“std:：_u1:：basic_regex:：_parse_ecma_exp”
__first=\uuuuu parse\uecma\uexp（\uuuuu first，\uuuu last）；
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2522:10:注意：在函数模板的实例化中
此处请求专门化“std:：_1:：basic_regex:：_parse”
{uuuu parse（uu p，u p+u.length（u p））}
^
Expression.cpp:3356:16:注意：在成员函数“std:：_1:：basic_regex:：basic_regex”的实例化中，此处请求
std:：regex txt_regex（“[a-z]+\\.txt”）；
^
在表达式.cpp:113中包含的文件中：
在包含于./StdAfx.h:23的文件中：
在/Applications/Xcode.app/Contents/Developer/Toolchains/xcodefault.xctoolchain/usr/include/c++/v1/algorithm:643中包含的文件中：
/Applications/Xcode.app/Contents/Developer/toolschains/xcodefault.xctoolschain/usr/include/c++/v1/memory:2051:9:错误：无法初始化成员子对象
类型为“std:：\u 1:：\u state*”且右值类型为“long”
：u值_u（VSTD:：forward（u））{}；
^        ~~~~~~~~~~~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2141:9:注意：在函数模板的实例化中
专门化'std:：uuuu 1:：uuu compressed\u pair\u elem:：uu compressed\u pair\u elem'已在此处请求
：_Base1（std:：forward（u_t）），_Base2（）{}
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:423:7:注意：在函数模板的实例化中
专门化'std:：uu 1:：u压缩对：：u压缩对'
在此请求
__端盖（空端）
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:473:5:注意：在成员函数的实例化中
“std:：uuuu 1:：uuu vector_base:：uu vector_base”已在此处请求
vector（）_NOEXCEPT_（是默认值还是可构造的：：值）
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:5536:21:注意：在成员函数的实例化中
此处请求了“std:：_1:：vector:：vector”
矢量状态；
^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2990:29：注意：在函数模板的实例化中
专门化“std:：uuuu 1:：basic_regex:：uu match_at_start_ecma”请求在此处
bool匹配=\uuuuuuu exp.\uuuuu匹配\uu在\uu start\u ecma(
^
/Applications/Xcode.app/Contents/Developer/toolschains/XcodeDefault.xctoolschain/usr/include/c++/v1/regex:2978:5:注意：（在回溯中跳过4个上下文；使用
-ftemplate backtrace limit=0以查看所有内容）
__前瞻（const basic_regex）&
// Simple regular expression matching
std::string fnames[] = {"foo.txt", "bar.txt", "baz.dat", "zoidberg"};
std::regex txt_regex("[a-z]+\\.txt");

for (const auto &fname : fnames) {
    std::cout << fname << ": " << std::regex_match(fname, txt_regex) << '\n';
} 

g++ -std=c++11 -DSTATIC_LIB -g -I . -I ../../../../openssl/iOS/include -o out/Expression.o -c Expression.cpp

In file included from Expression.cpp:113:
In file included from ./StdAfx.h:23:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/algorithm:643:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2051:9: error: cannot initialize a member subobject
      of type 'std::__1::sub_match<const char *> *' with an rvalue of type 'long'
      : __value_(_VSTD::forward<_Up>(__u)){};
        ^        ~~~~~~~~~~~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2151:9: note: in instantiation of function template
      specialization 'std::__1::__compressed_pair_elem<std::__1::sub_match<const char *> *, 0, false>::__compressed_pair_elem<long, void>' requested here
      : _Base1(std::forward<_U1>(__t1)), _Base2(std::forward<_U2>(__t2)) {}
        ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:432:7: note: in instantiation of function template
      specialization 'std::__1::__compressed_pair<std::__1::sub_match<const char *> *, std::__1::allocator<std::__1::sub_match<const char *> >
      >::__compressed_pair<long, const std::__1::allocator<std::__1::sub_match<const char *> > &>' requested here
      __end_cap_(nullptr, __a)
      ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:485:11: note: in instantiation of member function
      'std::__1::__vector_base<std::__1::sub_match<const char *>, std::__1::allocator<std::__1::sub_match<const char *> > >::__vector_base' requested here
        : __base(__a)
          ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:5355:7: note: in instantiation of member function
      'std::__1::vector<std::__1::sub_match<const char *>, std::__1::allocator<std::__1::sub_match<const char *> > >::vector' requested here
    : __matches_(__a),
      ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2988:34: note: in instantiation of member function
      'std::__1::match_results<const char *, std::__1::allocator<std::__1::sub_match<const char *> > >::match_results' requested here
    match_results<const _CharT*> __m;
                                 ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2978:5: note: (skipping 4 contexts in backtrace; use
      -ftemplate-backtrace-limit=0 to see all)
    __lookahead(const basic_regex<_CharT, _Traits>& __exp, bool __invert, __node<_CharT>* __s, unsigned __mexp)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4098:35: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_term<const char *>' requested here
        _ForwardIterator __temp = __parse_term(__first, __last);
                                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4074:31: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_alternative<const char *>' requested here
    _ForwardIterator __temp = __parse_alternative(__first, __last);
                              ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:3026:19: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_ecma_exp<const char *>' requested here
        __first = __parse_ecma_exp(__first, __last);
                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2522:10: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse<const char *>' requested here
        {__parse(__p, __p + __traits_.length(__p));}
         ^
Expression.cpp:3356:16: note: in instantiation of member function 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::basic_regex' requested here
    std::regex txt_regex("[a-z]+\\.txt");
               ^
In file included from Expression.cpp:113:
In file included from ./StdAfx.h:23:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/algorithm:643:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2051:9: error: cannot initialize a member subobject
      of type 'std::__1::__state<char> *' with an rvalue of type 'long'
      : __value_(_VSTD::forward<_Up>(__u)){};
        ^        ~~~~~~~~~~~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2141:9: note: in instantiation of function template
      specialization 'std::__1::__compressed_pair_elem<std::__1::__state<char> *, 0, false>::__compressed_pair_elem<long, void>' requested here
      : _Base1(std::forward<_Tp>(__t)), _Base2() {}
        ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:423:7: note: in instantiation of function template
      specialization 'std::__1::__compressed_pair<std::__1::__state<char> *, std::__1::allocator<std::__1::__state<char> > >::__compressed_pair<long, true>'
      requested here
      __end_cap_(nullptr)
      ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:473:5: note: in instantiation of member function
      'std::__1::__vector_base<std::__1::__state<char>, std::__1::allocator<std::__1::__state<char> > >::__vector_base' requested here
    vector() _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:5536:21: note: in instantiation of member function
      'std::__1::vector<std::__1::__state<char>, std::__1::allocator<std::__1::__state<char> > >::vector' requested here
    vector<__state> __states;
                    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2990:29: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__match_at_start_ecma<std::__1::allocator<std::__1::sub_match<const char *>
      > >' requested here
    bool __matched = __exp_.__match_at_start_ecma(
                            ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2978:5: note: (skipping 4 contexts in backtrace; use
      -ftemplate-backtrace-limit=0 to see all)
    __lookahead(const basic_regex<_CharT, _Traits>& __exp, bool __invert, __node<_CharT>* __s, unsigned __mexp)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4098:35: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_term<const char *>' requested here
        _ForwardIterator __temp = __parse_term(__first, __last);
                                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4074:31: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_alternative<const char *>' requested here
    _ForwardIterator __temp = __parse_alternative(__first, __last);
                              ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:3026:19: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_ecma_exp<const char *>' requested here
        __first = __parse_ecma_exp(__first, __last);
                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2522:10: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse<const char *>' requested here
        {__parse(__p, __p + __traits_.length(__p));}
         ^
Expression.cpp:3356:16: note: in instantiation of member function 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::basic_regex' requested here
    std::regex txt_regex("[a-z]+\\.txt");
               ^
In file included from Expression.cpp:113:
In file included from ./StdAfx.h:23:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/algorithm:643:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2141:9: error: no matching constructor for
      initialization of '__compressed_pair_elem<std::__1::sub_match<const char *> *, 0>'
      : _Base1(std::forward<_Tp>(__t)), _Base2() {}
        ^      ~~~~~~~~~~~~~~~~~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:423:7: note: in instantiation of function template
      specialization 'std::__1::__compressed_pair<std::__1::sub_match<const char *> *, std::__1::allocator<std::__1::sub_match<const char *> >
      >::__compressed_pair<long, true>' requested here
      __end_cap_(nullptr)
      ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/vector:473:5: note: in instantiation of member function
      'std::__1::__vector_base<std::__1::sub_match<const char *>, std::__1::allocator<std::__1::sub_match<const char *> > >::__vector_base' requested here
    vector() _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:1326:5: note: in instantiation of member function
      'std::__1::vector<std::__1::sub_match<const char *>, std::__1::allocator<std::__1::sub_match<const char *> > >::vector' requested here
    __state()
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:5545:28: note: in instantiation of member function
      'std::__1::__state<char>::__state' requested here
        __states.push_back(__state());
                           ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2990:29: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__match_at_start_ecma<std::__1::allocator<std::__1::sub_match<const char *>
      > >' requested here
    bool __matched = __exp_.__match_at_start_ecma(
                            ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2978:5: note: (skipping 4 contexts in backtrace; use
      -ftemplate-backtrace-limit=0 to see all)
    __lookahead(const basic_regex<_CharT, _Traits>& __exp, bool __invert, __node<_CharT>* __s, unsigned __mexp)
    ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4098:35: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_term<const char *>' requested here
        _ForwardIterator __temp = __parse_term(__first, __last);
                                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:4074:31: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_alternative<const char *>' requested here
    _ForwardIterator __temp = __parse_alternative(__first, __last);
                              ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:3026:19: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse_ecma_exp<const char *>' requested here
        __first = __parse_ecma_exp(__first, __last);
                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/regex:2522:10: note: in instantiation of function template
      specialization 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::__parse<const char *>' requested here
        {__parse(__p, __p + __traits_.length(__p));}
         ^
Expression.cpp:3356:16: note: in instantiation of member function 'std::__1::basic_regex<char, std::__1::regex_traits<char> >::basic_regex' requested here
    std::regex txt_regex("[a-z]+\\.txt");
               ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2037:8: note: candidate constructor
      (the implicit copy constructor) not viable: no known conversion from 'long' to 'const std::__1::__compressed_pair_elem<std::__1::sub_match<const char
      *> *, 0, false>' for 1st argument
struct __compressed_pair_elem {
       ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2037:8: note: candidate constructor
      (the implicit move constructor) not viable: no known conversion from 'long' to 'std::__1::__compressed_pair_elem<std::__1::sub_match<const char *> *,
      0, false>' for 1st argument
struct __compressed_pair_elem {
       ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2050:3: note: candidate template ignored:
      substitution failure [with _Up = long, $1 = void]
  __compressed_pair_elem(_Up&& __u)
  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2055:3: note: candidate constructor template not
      viable: requires 3 arguments, but 1 was provided
  __compressed_pair_elem(piecewise_construct_t, tuple<_Args...> __args,
  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/memory:2043:39: note: candidate constructor not viable:
      requires 0 arguments, but 1 was provided
  _LIBCPP_INLINE_VISIBILITY constexpr __compressed_pair_elem() : __value_() {}

#define nullptr 0l

#include <regex>
#include <iostream>

int main ()
{
    std::string fnames[] = {"foo.txt", "bar.txt", "baz.dat", "zoidberg"};
    std::regex txt_regex("[a-z]+\\.txt");

    for (const auto &fname : fnames)
        std::cout << fname << ": " << std::regex_match(fname, txt_regex) << '\n';
}