Fix building and using the library with MinGW -std=c++{98,11} options.

These options enable "strict ANSI" mode in MinGW which omits declarations of
POSIX functions from the standard headers. To allow the library and, possibly
even more importantly, the user code including our headers, to compile with
these options, declare the functions that we need ourselves.

This might appear to go against the spirit of "strict ANSI" mode, but the only
alternative would be to not use such functions at all and silently cripple the
library when -std=c++NN is used, compared to -std=g++NN case, and this doesn't
seem appealing neither.

Closes #16984.

include/wx/filefn.h

@@ -197,8 +197,22 @@ enum wxPosixPermissions
         #define wxFtell _ftelli64
     #elif wxCHECK_MINGW32_VERSION(3, 5) // mingw-runtime version (not gcc)
         #define wxHAS_HUGE_STDIO_FILES
+
+        wxDECL_FOR_STRICT_MINGW32(int, fseeko64, (FILE*, long long, int));
         #define wxFseek fseeko64
-        #define wxFtell ftello64
+
+        #ifdef wxNEEDS_STRICT_ANSI_WORKAROUNDS
+            // Unfortunately ftello64() is not defined in the library for
+            // whatever reason but as an inline function, so define wxFtell()
+            // here similarly.
+            inline long long wxFtell(FILE* fp)
+            {
+                fpos_t pos;
+                return fgetpos(fp, &pos) == 0 ? pos : -1LL;
+            }
+        #else
+            #define wxFtell ftello64
+        #endif
     #endif
 
     // other Windows compilers (Borland) don't have huge file support (or at
@@ -324,6 +338,9 @@ enum wxPosixPermissions
             #define wxCRT_OpenW       _wopen
         #endif
 
+        wxDECL_FOR_STRICT_MINGW32(int, _wmkdir, (const wchar_t*))
+        wxDECL_FOR_STRICT_MINGW32(int, _wrmdir, (const wchar_t*))
+
         #define   wxCRT_AccessW     _waccess
         #define   wxCRT_ChmodW      _wchmod
         #define   wxCRT_MkDirW      _wmkdir

include/wx/math.h

@@ -71,6 +71,10 @@
     #else
         #define wxFinite(x) isfinite(x)
     #endif
+#elif defined(wxNEEDS_STRICT_ANSI_WORKAROUNDS)
+    wxDECL_FOR_STRICT_MINGW32(int, _finite, (double));
+
+    #define wxFinite(x) _finite(x)
 #elif ( defined(__GNUG__)||defined(__GNUWIN32__)||defined(__DJGPP__)|| \
       defined(__SGI_CC__)||defined(__SUNCC__)||defined(__XLC__)|| \
       defined(__HPUX__) ) && ( !defined(wxOSX_USE_IPHONE) || wxOSX_USE_IPHONE == 0 )

include/wx/msw/gccpriv.h

@@ -132,5 +132,28 @@
     #endif
 #endif
 
+/*
+    Traditional MinGW (but not MinGW-w64 nor TDM-GCC) omits many POSIX
+    functions from their headers when compiled with __STRICT_ANSI__ defined.
+    Unfortunately this means that they are not available when using -std=c++98
+    (not very common) or -std=c++11 (much more so), but we still need them even
+    in this case. As the intention behind using -std=c++11 is probably to get
+    the new C++11 features and not disable the use of POSIX functions, we just
+    manually declare the functions we need in this case if necessary.
+ */
+#if defined(__MINGW32_TOOLCHAIN__) && defined(__STRICT_ANSI__)
+    #define wxNEEDS_STRICT_ANSI_WORKAROUNDS
+
+    /*
+        This macro is somewhat unusual as it takes the list of parameters
+        inside parentheses and includes semicolon inside it as putting the
+        semicolon outside wouldn't do the right thing when this macro is empty.
+     */
+    #define wxDECL_FOR_STRICT_MINGW32(rettype, func, params) \
+        extern "C" _CRTIMP rettype __cdecl __MINGW_NOTHROW func params ;
+#else
+    #define wxDECL_FOR_STRICT_MINGW32(rettype, func, params)
+#endif
+
 #endif
   /* _WX_MSW_GCCPRIV_H_ */

include/wx/msw/private.h

@@ -181,6 +181,8 @@ extern LONG APIENTRY _EXPORT
    || defined(__MINGW32__)
     #define wxGetOSFHandle(fd) ((HANDLE)_get_osfhandle(fd))
     #define wxOpenOSFHandle(h, flags) (_open_osfhandle(wxPtrToUInt(h), flags))
+
+    wxDECL_FOR_STRICT_MINGW32(FILE*, _fdopen, (int, const char*))
     #define wx_fdopen _fdopen
 #endif
 

include/wx/platform.h

@@ -430,6 +430,7 @@
 #    define wxCHECK_W32API_VERSION(maj, min) (0)
 #    undef wxCHECK_MINGW32_VERSION
 #    define wxCHECK_MINGW32_VERSION( major, minor ) (0)
+#    define wxDECL_FOR_STRICT_MINGW32(rettype, func, params)
 #endif
 
 

include/wx/wxcrtbase.h

@@ -73,6 +73,9 @@
 
 #ifdef wxNEED_ISASCII
     inline int isascii(int c) { return (unsigned)c < 0x80; }
+
+    // Avoid further (re)definitions of it.
+    #define isascii isascii
 #endif
 
 #ifdef _WIN32_WCE
@@ -451,6 +454,11 @@ WXDLLIMPEXP_BASE wchar_t *wxCRT_StrtokW(wchar_t *psz, const wchar_t *delim, wcha
     #define wxCRT_Rename  rename
 
 #else /* Unicode filenames */
+    wxDECL_FOR_STRICT_MINGW32(FILE*, _wfopen, (const wchar_t*, const wchar_t*))
+    wxDECL_FOR_STRICT_MINGW32(FILE*, _wfreopen, (const wchar_t*, const wchar_t*, FILE*))
+    wxDECL_FOR_STRICT_MINGW32(int, _wrename, (const wchar_t*, const wchar_t*))
+    wxDECL_FOR_STRICT_MINGW32(int, _wremove, (const wchar_t*))
+
     /* WinCE CRT doesn't provide these functions so use our own */
     #ifdef __WXWINCE__
         WXDLLIMPEXP_BASE int wxCRT_Rename(const wchar_t *src,