当包含来自STL的C2039和C2873时

Question

我正在尝试用msvc2019编译器编译一个项目，我知道这个编译器以前已经编译过。事实上，我实际上是在更新它的构建系统。我在标准模板库的源代码中遇到一个奇怪的问题。基本上，该项目包括<cctype>，它包含以下代码片段：

_STD_BEGIN
using _CSTD isalnum;
using _CSTD isalpha;
using _CSTD iscntrl;
using _CSTD isdigit;
using _CSTD isgraph;
using _CSTD islower;
using _CSTD isprint;
using _CSTD ispunct;
using _CSTD isspace;
using _CSTD isupper;
using _CSTD isxdigit;
using _CSTD tolower;
using _CSTD toupper;

using _CSTD isblank;
_STD_END

但是当我编译我的项目时，这些声明都是错误的。

C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(38): error C2039: 'isalnum': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(38): error C2873: 'isalnum': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(39): error C2039: 'isalpha': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(39): error C2873: 'isalpha': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(40): error C2039: 'iscntrl': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(40): error C2873: 'iscntrl': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(41): error C2039: 'isdigit': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(41): error C2873: 'isdigit': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(42): error C2039: 'isgraph': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(42): error C2873: 'isgraph': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(43): error C2039: 'islower': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(43): error C2873: 'islower': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(44): error C2039: 'isprint': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(44): error C2873: 'isprint': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(45): error C2039: 'ispunct': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(45): error C2873: 'ispunct': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(46): error C2039: 'isspace': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(46): error C2873: 'isspace': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(47): error C2039: 'isupper': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(47): error C2873: 'isupper': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(48): error C2039: 'isxdigit': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(48): error C2873: 'isxdigit': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(49): error C2039: 'tolower': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(49): error C2873: 'tolower': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(50): error C2039: 'toupper': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(50): error C2873: 'toupper': symbol cannot be used in a using-declaration
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(52): error C2039: 'isblank': is not a member of '`global namespace''
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.27.29110\include\cctype(52): error C2873: 'isblank': symbol cannot be used in a using-declaration

c++11和c++14的结果都是一样的。我试着做一个最小的工作示例，但做不到，因为我的玩具项目包含和使用<cctype>编译时没有问题。因此，在某个地方，我的项目设置肯定有问题。

我知道这会很艰难，但是有没有人对这里可能发生的事情有任何想法？

Answer 1

我在macOS平台上也有同样的错误；我的解决方案是#include <_ctype.h> --这个标头定义了is*函数。