Add wxCHECK_GLIBC_VERSION() and cleanup glibc version checks

Use this macro where possible and simplify the checks in a couple of
places where it isn't (because we're checking for an exact glibc
version).

No real changes.

include/wx/private/glibc.h

@@ -0,0 +1,25 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/private/glibc.h
+// Purpose:     glibc-specific private wx header
+// Author:      Vadim Zeitlin
+// Created:     2022-06-23
+// Copyright:   (c) 2022 Vadim Zeitlin <vadim@wxwidgets.org>
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_PRIVATE_GLIBC_H_
+#define _WX_PRIVATE_GLIBC_H_
+
+// Ensure that a header include __GLIBC__ is defined.
+#include <string.h>
+
+// Macro for testing glibc version similar to wxCHECK_GCC_VERSION().
+#if defined(__GLIBC__) && defined(__GLIBC_MINOR__)
+    #define wxCHECK_GLIBC_VERSION( major, minor ) \
+        ( ( __GLIBC__ > (major) ) \
+            || ( __GLIBC__ == (major) && __GLIBC_MINOR__ >= (minor) ) )
+#else
+    #define wxCHECK_GLIBC_VERSION( major, minor ) 0
+#endif
+
+#endif // _WX_PRIVATE_GLIBC_H_

include/wx/wxcrtbase.h

@@ -594,7 +594,7 @@ WXDLLIMPEXP_BASE size_t wxCRT_StrftimeW(wchar_t *s, size_t max,
 #define wxCRT_IsxdigitW(c)  iswxdigit(c)
 
 #ifdef __GLIBC__
-    #if defined(__GLIBC__) && (__GLIBC__ == 2) && (__GLIBC_MINOR__ == 0)
+    #if (__GLIBC__ == 2) && (__GLIBC_MINOR__ == 0)
         /* /usr/include/wctype.h incorrectly declares translations */
         /* tables which provokes tons of compile-time warnings -- try */
         /* to correct this */

src/common/strconv.cpp

@@ -38,6 +38,7 @@
 #ifdef HAVE_ICONV
     #include <iconv.h>
     #include "wx/thread.h"
+    #include "wx/private/glibc.h"
 #endif
 
 #include "wx/encconv.h"
@@ -2037,7 +2038,7 @@ wxMBConvUTF32swap::FromWChar(char *dst, size_t dstLen,
 //     bytes-left-in-input buffer is non-zero. Hence, this alternative test for
 //     iconv() failure.
 //     [This bug does not appear in glibc 2.2.]
-#if defined(__GLIBC__) && __GLIBC__ == 2 && __GLIBC_MINOR__ <= 1
+#if wxCHECK_GLIBC_VERSION(2, 0) && !wxCHECK_GLIBC_VERSION(2, 2)
 #define ICONV_FAILED(cres, bufLeft) ((cres == (size_t)-1) && \
                                      (errno != E2BIG || bufLeft != 0))
 #else

src/unix/sockunix.cpp

@@ -32,9 +32,7 @@
 #  define WX_SOCKLEN_T unsigned int
 #else
 #  ifdef __GLIBC__
-#    if __GLIBC__ == 2
-#      define WX_SOCKLEN_T socklen_t
-#    endif
+#    define WX_SOCKLEN_T socklen_t
 #  elif defined(__WXMAC__)
 #    define WX_SOCKLEN_T socklen_t
 #  else

src/unix/utilsunx.cpp

@@ -54,6 +54,7 @@
 
 #include "wx/private/selectdispatcher.h"
 #include "wx/private/fdiodispatcher.h"
+#include "wx/private/glibc.h"
 #include "wx/unix/private/execute.h"
 #include "wx/unix/pipe.h"
 #include "wx/unix/private.h"
@@ -216,8 +217,7 @@ void wxMilliSleep(unsigned long milliseconds)
 
 void wxSecureZeroMemory(void* v, size_t n)
 {
-#if (defined(__GLIBC__) && \
-        (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 25))) || \
+#if wxCHECK_GLIBC_VERSION(2, 25) || \
     (defined(__FreeBSD__) && __FreeBSD__ >= 11)
     // This non-standard function is somewhat widely available elsewhere too,
     // but may be found in a non-standard header file, or in a library that is

tests/intl/intltest.cpp

@@ -20,6 +20,8 @@
 #include "wx/intl.h"
 #include "wx/uilocale.h"
 
+#include "wx/private/glibc.h"
+
 #if wxUSE_INTL
 
 // ----------------------------------------------------------------------------
@@ -175,7 +177,7 @@ void IntlTestCase::DateTimeFmtFrench()
 #ifdef __GLIBC__
     // Versions of glibc up to 2.7 wrongly used periods for French locale
     // separator.
-#if __GLIBC__ > 2 || __GLIBC_MINOR__ >= 8
+#if wxCHECK_GLIBC_VERSION(2, 8)
     static const char *FRENCH_DATE_FMT = "%d/%m/%Y";
 #else
     static const char *FRENCH_DATE_FMT = "%d.%m.%Y";