<cctype>: do not defend against isalnum/etc. macros

[fsb4000]

Fixes #259

C:\Program Files (x86)\Windows Kits\10\Include\10.0.19041.0\ucrt\ctype.h

#if defined _CRT_DISABLE_PERFCRIT_LOCKS && !defined _DLL && !defined __cplusplus
        #define isalpha(c)  (MB_CUR_MAX > 1 ? _isctype(c, _ALPHA) : __chvalidchk(c, _ALPHA))
        #define isupper(c)  (MB_CUR_MAX > 1 ? _isctype(c, _UPPER) : __chvalidchk(c, _UPPER))
        #define islower(c)  (MB_CUR_MAX > 1 ? _isctype(c, _LOWER) : __chvalidchk(c, _LOWER))
        #define isdigit(c)  (MB_CUR_MAX > 1 ? _isctype(c, _DIGIT) : __chvalidchk(c, _DIGIT))
        #define isxdigit(c) (MB_CUR_MAX > 1 ? _isctype(c, _HEX)   : __chvalidchk(c, _HEX))
        #define isspace(c)  (MB_CUR_MAX > 1 ? _isctype(c, _SPACE) : __chvalidchk(c, _SPACE))
        #define ispunct(c)  (MB_CUR_MAX > 1 ? _isctype(c, _PUNCT) : __chvalidchk(c, _PUNCT))
        #define isblank(c)  (MB_CUR_MAX > 1 ? (((c) == '\t') ? _BLANK : _isctype(c, _BLANK)) : (((c) == '\t') ? _BLANK : __chvalidchk(c, _BLANK)))
        #define isalnum(c)  (MB_CUR_MAX > 1 ? _isctype(c, _ALPHA | _DIGIT) : __chvalidchk(c, (_ALPHA | _DIGIT)))
        #define isprint(c)  (MB_CUR_MAX > 1 ? _isctype(c, _BLANK | _PUNCT | _ALPHA | _DIGIT) : __chvalidchk(c, (_BLANK | _PUNCT | _ALPHA | _DIGIT)))
        #define isgraph(c)  (MB_CUR_MAX > 1 ? _isctype(c, _PUNCT | _ALPHA | _DIGIT) : __chvalidchk(c, (_PUNCT | _ALPHA | _DIGIT)))
        #define iscntrl(c)  (MB_CUR_MAX > 1 ? _isctype(c, _CONTROL) : __chvalidchk(c, _CONTROL))
    #endif

also

_Check_return_ _CRT_JIT_INTRINSIC _ACRTIMP int __cdecl isalpha(_In_ int _C);
_Check_return_ _CRT_JIT_INTRINSIC _ACRTIMP int __cdecl isupper(_In_ int _C);
_Check_return_ _CRT_JIT_INTRINSIC _ACRTIMP int __cdecl islower(_In_ int _C);
...
_Check_return_ _ACRTIMP int __cdecl iscntrl(_In_ int _C);

So non macro versions exist and the macros guarded with !defined __cplusplus

[AlexGuteniev]

But what if older SDK is used?

[fsb4000]

I opened my oldest VS installed: 2005 with Windows 2003 SDK. (the last SDK and VS which support Windows 98)

<cctype> has

// remove any (improper) macro overrides
#undef isalnum
#undef isalpha
#undef isblank
#undef iscntrl
#undef isdigit
#undef isgraph
#undef islower
#undef isprint
#undef ispunct
#undef isspace
#undef isupper
#undef isxdigit
#undef tolower
#undef toupper

But it seems that is not necessary even for the Windows 2003 SDK

Some screenshots: https://imgur.com/a/GApNpBX

[StephanTLavavej]

Thanks for the archaeological investigation here!

[StephanTLavavej]

I'm mirroring this to an MSVC-internal PR. Please notify me if any further changes are pushed.

[StephanTLavavej]

#define isalnum ThanksForRemovingThisUnnecessaryCode!