headers: fix _CONST_RETURN warnings

With previous changes to _CONST_RETURN, GCC 7-14 will warn about strchr
and similar functions with -Wbuiltin-declaration-mismatch, as GCC's
builtin versions of these functions return non-const pointers even in
C++ mode. Other versions of GCC and all versions of Clang are fine.

This commit fixes this by moving all C++ declartions of these functions
under extern "C++", similar to what glibc does. The difference between
we and glibc is that we only use __asm__ for the const versions of these
functions, while glibc uses it for both. This is to avoid -Wodr warnings
under LTO.

Signed-off-by: Zhongteng Gui <dragon-archer@outlook.com>
Signed-off-by: LIU Hao <lh_mouse@126.com>

mingw-w64-headers/crt/corecrt_memory.h

diff --git a/mingw-w64-headers/crt/corecrt_memory.h b/mingw-w64-headers/crt/corecrt_memory.h
index 7eb4573..779887d 100644
--- a/mingw-w64-headers/crt/corecrt_memory.h
+++ b/mingw-w64-headers/crt/corecrt_memory.h
@@ -14,7 +14,6 @@
 #if !defined(__STRICT_ANSI__) || defined(_GNU_SOURCE) || __STDC_VERSION__ + 0 >= 202311L || _XOPEN_SOURCE + 0 >= 600
   void * __cdecl memccpy(void *_Dst,const void *_Src,int _Val,size_t _Size);
 #endif
-  _CONST_RETURN void *__cdecl memchr(const void *_Buf ,int _Val,size_t _MaxCount);
   _CRTIMP int __cdecl _memicmp(const void *_Buf1,const void *_Buf2,size_t _Size);
   _CRTIMP int __cdecl _memicmp_l(const void *_Buf1,const void *_Buf2,size_t _Size,_locale_t _Locale);
   int __cdecl memcmp(const void *_Buf1,const void *_Buf2,size_t _Size);
@@ -34,8 +33,13 @@
 _CRT_END_C_HEADER
 
 #ifdef __cplusplus
-extern "C++" inline void* memchr(void* __s, int __c, size_t __n)
-{ return const_cast<void*>(memchr(const_cast<const void*>(__s), __c, __n)); }
+extern "C++" {
+  const void* __cdecl memchr(const void*, int, size_t) __MINGW_ASM_CALL(memchr);
+  inline void* __cdecl memchr(void* _Buf, int _Val, size_t _MaxCount)
+  { return const_cast<void*>(memchr(const_cast<const void*>(_Buf), _Val, _MaxCount)); }
+}
+#else
+  void* __cdecl memchr(const void* _Buf, int _Val, size_t _MaxCount);
 #endif
 
 #endif

mingw-w64-headers/crt/corecrt_wstring.h

diff --git a/mingw-w64-headers/crt/corecrt_wstring.h b/mingw-w64-headers/crt/corecrt_wstring.h
index 22227a7..3231117 100644
--- a/mingw-w64-headers/crt/corecrt_wstring.h
+++ b/mingw-w64-headers/crt/corecrt_wstring.h
@@ -26,7 +26,6 @@
 #pragma pop_macro("_wcsdup")
 #endif
   wchar_t *__cdecl wcscat(wchar_t * __restrict__ _Dest,const wchar_t * __restrict__ _Source) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
-  _CONST_RETURN wchar_t *__cdecl wcschr(const wchar_t *_Str,wchar_t _Ch);
   int __cdecl wcscmp(const wchar_t *_Str1,const wchar_t *_Str2);
   wchar_t *__cdecl wcscpy(wchar_t * __restrict__ _Dest,const wchar_t * __restrict__ _Source) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
   size_t __cdecl wcscspn(const wchar_t *_Str,const wchar_t *_Control);
@@ -36,10 +35,7 @@
   int __cdecl wcsncmp(const wchar_t *_Str1,const wchar_t *_Str2,size_t _MaxCount);
   wchar_t *__cdecl wcsncpy(wchar_t * __restrict__ _Dest,const wchar_t * __restrict__ _Source,size_t _Count) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
   wchar_t *__cdecl _wcsncpy_l(wchar_t * __restrict__ _Dest,const wchar_t * __restrict__ _Source,size_t _Count,_locale_t _Locale) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
-  _CONST_RETURN wchar_t *__cdecl wcspbrk(const wchar_t *_Str,const wchar_t *_Control);
-  _CONST_RETURN wchar_t *__cdecl wcsrchr(const wchar_t *_Str,wchar_t _Ch);
   size_t __cdecl wcsspn(const wchar_t *_Str,const wchar_t *_Control);
-  _CONST_RETURN wchar_t *__cdecl wcsstr(const wchar_t *_Str,const wchar_t *_SubStr);
   _CRTIMP wchar_t *__cdecl wcstok(wchar_t * __restrict__ _Str,const wchar_t * __restrict__ _Delim,wchar_t ** __restrict__ _Ptr) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
   _CRTIMP wchar_t *__cdecl _wcstok(wchar_t * __restrict__ _Str,const wchar_t * __restrict__ _Delim) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
 #if defined(_CRT_NON_CONFORMING_WCSTOK) && !defined(__cplusplus)
@@ -94,24 +90,29 @@
 
 _CRT_END_C_HEADER
 
-/**
- * ISO C++ requires both const and non-const versions of these functions.
- * The const versions have been declared above. The non-const versions are declared here.
- */
-#ifdef __CORRECT_ISO_CPP_WCHAR_H_PROTO
+#ifdef __cplusplus
 extern "C++" {
-  inline wchar_t* wcschr(wchar_t* __p, wchar_t __c)
-  { return const_cast<wchar_t*>(wcschr(const_cast<const wchar_t*>(__p), __c)); }
+  const wchar_t* __cdecl wcschr(const wchar_t*, wchar_t) __MINGW_ASM_CALL(wcschr);
+  inline wchar_t* wcschr(wchar_t* _Str, wchar_t _Ch)
+  { return const_cast<wchar_t*>(wcschr(const_cast<const wchar_t*>(_Str), _Ch)); }
 
-  inline wchar_t* wcspbrk(wchar_t* __s1, const wchar_t* __s2)
-  { return const_cast<wchar_t*>(wcspbrk(const_cast<const wchar_t*>(__s1), __s2)); }
+  const wchar_t* __cdecl wcspbrk(const wchar_t*, const wchar_t*) __MINGW_ASM_CALL(wcspbrk);
+  inline wchar_t* wcspbrk(wchar_t* _Str, const wchar_t* _Control)
+  { return const_cast<wchar_t*>(wcspbrk(const_cast<const wchar_t*>(_Str), _Control)); }
 
-  inline wchar_t* wcsrchr(wchar_t* __p, wchar_t __c)
-  { return const_cast<wchar_t*>(wcsrchr(const_cast<const wchar_t*>(__p), __c)); }
+  const wchar_t* __cdecl wcsrchr(const wchar_t*, wchar_t) __MINGW_ASM_CALL(wcsrchr);
+  inline wchar_t* wcsrchr(wchar_t* _Str, wchar_t _Ch)
+  { return const_cast<wchar_t*>(wcsrchr(const_cast<const wchar_t*>(_Str), _Ch)); }
 
-  inline wchar_t* wcsstr(wchar_t* __s1, const wchar_t* __s2)
-  { return const_cast<wchar_t*>(wcsstr(const_cast<const wchar_t*>(__s1), __s2)); }
+  const wchar_t* __cdecl wcsstr(const wchar_t*, const wchar_t*) __MINGW_ASM_CALL(wcsstr);
+  inline wchar_t* wcsstr(wchar_t* _Str, const wchar_t* _SubStr)
+  { return const_cast<wchar_t*>(wcsstr(const_cast<const wchar_t*>(_Str), _SubStr)); }
 }
+#else
+  wchar_t* __cdecl wcschr(const wchar_t* _Str, wchar_t _Ch);
+  wchar_t* __cdecl wcspbrk(const wchar_t* _Str, const wchar_t* _Control);
+  wchar_t* __cdecl wcsrchr(const wchar_t* _Str, wchar_t _Ch);
+  wchar_t* __cdecl wcsstr(const wchar_t* _Str, const wchar_t* _SubStr);
 #endif
 
 #endif

mingw-w64-headers/crt/string.h

diff --git a/mingw-w64-headers/crt/string.h b/mingw-w64-headers/crt/string.h
index 01859e9..86e44df 100644
--- a/mingw-w64-headers/crt/string.h
+++ b/mingw-w64-headers/crt/string.h
@@ -60,7 +60,6 @@
 #if !defined(__STRICT_ANSI__) || defined(_GNU_SOURCE) || __STDC_VERSION__ + 0 >= 202311L || _POSIX_C_SOURCE + 0 >= 200809L || _XOPEN_SOURCE + 0 >= 700
   char *__cdecl strndup(const char *_Src,size_t _MaxCount);
 #endif
-  _CONST_RETURN char *__cdecl strchr(const char *_Str,int _Val);
   _CRTIMP int __cdecl _stricmp(const char *_Str1,const char *_Str2);
   _CRTIMP int __cdecl _strcmpi(const char *_Str1,const char *_Str2);
   _CRTIMP int __cdecl _stricmp_l(const char *_Str1,const char *_Str2,_locale_t _Locale);
@@ -84,11 +83,8 @@
   char *strncpy(char * __restrict__ _Dest,const char * __restrict__ _Source,size_t _Count) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
   _CRTIMP char *__cdecl _strnset(char *_Str,int _Val,size_t _MaxCount) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
   _CRTIMP char *__cdecl _strnset_l(char *str,int c,size_t count,_locale_t _Locale) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
-  _CONST_RETURN char *__cdecl strpbrk(const char *_Str,const char *_Control);
-  _CONST_RETURN char *__cdecl strrchr(const char *_Str,int _Ch);
   _CRTIMP char *__cdecl _strrev(char *_Str);
   size_t __cdecl strspn(const char *_Str,const char *_Control);
-  _CONST_RETURN char *__cdecl strstr(const char *_Str,const char *_SubStr);
   _CRTIMP char *__cdecl strtok(char * __restrict__ _Str,const char * __restrict__ _Delim) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
 #pragma push_macro("strtok_r")
 #undef strtok_r
@@ -122,20 +118,29 @@
 
 _CRT_END_C_HEADER
 
-#ifdef __CORRECT_ISO_CPP_STRING_H_PROTO
+#ifdef __cplusplus
 extern "C++" {
-  inline char* strchr(char* __s, int __n)
-  { return const_cast<char*>(strchr(const_cast<const char*>(__s), __n)); }
+  const char* __cdecl strchr(const char*, int) __MINGW_ASM_CALL(strchr);
+  inline char* __cdecl strchr(char* _Str, int _Val)
+  { return const_cast<char*>(strchr(const_cast<const char*>(_Str), _Val)); }
 
-  inline char* strpbrk(char* __s1, const char* __s2)
-  { return const_cast<char*>(strpbrk(const_cast<const char*>(__s1), __s2)); }
+  const char* __cdecl strpbrk(const char*, const char*) __MINGW_ASM_CALL(strpbrk);
+  inline char* __cdecl strpbrk(char* _Str, const char* _Control)
+  { return const_cast<char*>(strpbrk(const_cast<const char*>(_Str), _Control)); }
 
-  inline char* strrchr(char* __s, int __n)
-  { return const_cast<char*>(strrchr(const_cast<const char*>(__s), __n)); }
+  const char* __cdecl strrchr(const char*, int) __MINGW_ASM_CALL(strrchr);
+  inline char* __cdecl strrchr(char* _Str, int _Val)
+  { return const_cast<char*>(strrchr(const_cast<const char*>(_Str), _Val)); }
 
-  inline char* strstr(char* __s1, const char* __s2)
-  { return const_cast<char*>(strstr(const_cast<const char*>(__s1), __s2)); }
+  const char* __cdecl strstr(const char*, const char*) __MINGW_ASM_CALL(strstr);
+  inline char* __cdecl strstr(char* _Str, const char* _SubStr)
+  { return const_cast<char*>(strstr(const_cast<const char*>(_Str), _SubStr)); }
 }
+#else
+  char* __cdecl strchr(const char* _Str, int _Val);
+  char* __cdecl strpbrk(const char* _Str, const char* _Control);
+  char* __cdecl strrchr(const char* _Str, int _Val);
+  char* __cdecl strstr(const char* _Str, const char* _SubStr);
 #endif
 
 #include <sec_api/string_s.h>

mingw-w64-headers/crt/wchar.h

diff --git a/mingw-w64-headers/crt/wchar.h b/mingw-w64-headers/crt/wchar.h
index 357d06b..705f153 100644
--- a/mingw-w64-headers/crt/wchar.h
+++ b/mingw-w64-headers/crt/wchar.h
@@ -183,7 +183,6 @@
 
 #ifndef __NO_ISOCEXT /* these need static lib libmingwex.a */
   wchar_t *__cdecl wmemset(wchar_t *s, wchar_t c, size_t n);
-  _CONST_RETURN wchar_t *__cdecl wmemchr(const wchar_t *s, wchar_t c, size_t n);
   int __cdecl wmemcmp(const wchar_t *s1, const wchar_t *s2,size_t n);
   wchar_t *__cdecl wmemcpy(wchar_t * __restrict__ s1,const wchar_t * __restrict__ s2,size_t n) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
   wchar_t * __cdecl wmempcpy (wchar_t *_Dst, const wchar_t *_Src, size_t _Size);
@@ -192,16 +191,25 @@
   __MINGW_EXTENSION long long __cdecl wcstoll(const wchar_t * __restrict__ nptr,wchar_t ** __restrict__ endptr, int base);
   __MINGW_EXTENSION unsigned long long __cdecl wcstoull(const wchar_t * __restrict__ nptr,wchar_t ** __restrict__ endptr, int base);
 
-#ifdef __CORRECT_ISO_CPP_WCHAR_H_PROTO
-  extern "C++" inline wchar_t* wmemchr(wchar_t* __p, wchar_t __c, size_t __n)
-  { return const_cast<wchar_t*>(wmemchr(const_cast<const wchar_t*>(__p), __c, __n)); }
+#ifdef __cplusplus
+  extern "C++" {
+    const wchar_t* __cdecl wmemchr(const wchar_t*, wchar_t, size_t) __MINGW_ASM_CALL(wmemchr);
+    inline wchar_t* __cdecl wmemchr(wchar_t* _Buf, wchar_t _Val, size_t _MaxCount)
+    { return const_cast<wchar_t*>(wmemchr(const_cast<const wchar_t*>(_Buf), _Val, _MaxCount)); }
+  }
+#else
+  wchar_t* __cdecl wmemchr(const wchar_t* _Buf, wchar_t _Val, size_t _MaxCount);
 #endif
+
 #endif /* __NO_ISOCEXT */
 
   void *__cdecl memmove(void *_Dst,const void *_Src,size_t _MaxCount);
   void *__cdecl memcpy(void * __restrict__ _Dst,const void * __restrict__ _Src,size_t _MaxCount) __MINGW_ATTRIB_DEPRECATED_SEC_WARN;
 #ifndef __CRT__NO_INLINE
   __CRT_INLINE int __cdecl fwide(FILE *_F,int _M) { (void)_F; return (_M); }
+#ifdef __cplusplus
+  extern "C++"
+#endif
   __CRT_INLINE _CONST_RETURN wchar_t *__cdecl wmemchr(const wchar_t *_S,wchar_t _C,size_t _N) {
     if (_S) {
       for ( ; 0 < _N; ++_S, --_N)