use unsetenv() instead of setenv(var, NULL) which is invalid

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@47942 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

configure

@@ -40211,6 +40211,102 @@ _ACEOF
 fi
 done
 
+if test "$ac_cv_func_setenv" = "yes"; then
+
+for ac_func in unsetenv
+do
+as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
+{ echo "$as_me:$LINENO: checking for $ac_func" >&5
+echo $ECHO_N "checking for $ac_func... $ECHO_C" >&6; }
+if { as_var=$as_ac_var; eval "test \"\${$as_var+set}\" = set"; }; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+/* Define $ac_func to an innocuous variant, in case <limits.h> declares $ac_func.
+   For example, HP-UX 11i <limits.h> declares gettimeofday.  */
+#define $ac_func innocuous_$ac_func
+
+/* System header to define __stub macros and hopefully few prototypes,
+    which can conflict with char $ac_func (); below.
+    Prefer <limits.h> to <assert.h> if __STDC__ is defined, since
+    <limits.h> exists even on freestanding compilers.  */
+
+#ifdef __STDC__
+# include <limits.h>
+#else
+# include <assert.h>
+#endif
+
+#undef $ac_func
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char $ac_func ();
+/* The GNU C library defines this for functions which it implements
+    to always fail with ENOSYS.  Some functions are actually named
+    something starting with __ and the normal name is an alias.  */
+#if defined __stub_$ac_func || defined __stub___$ac_func
+choke me
+#endif
+
+int
+main ()
+{
+return $ac_func ();
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_link") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest$ac_exeext &&
+       $as_test_x conftest$ac_exeext; then
+  eval "$as_ac_var=yes"
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	eval "$as_ac_var=no"
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest_ipa8_conftest.oo \
+      conftest$ac_exeext conftest.$ac_ext
+fi
+ac_res=`eval echo '${'$as_ac_var'}'`
+	       { echo "$as_me:$LINENO: result: $ac_res" >&5
+echo "${ECHO_T}$ac_res" >&6; }
+if test `eval echo '${'$as_ac_var'}'` = yes; then
+  cat >>confdefs.h <<_ACEOF
+#define `echo "HAVE_$ac_func" | $as_tr_cpp` 1
+_ACEOF
+
+fi
+done
+
+fi
 
 HAVE_SOME_SLEEP_FUNC=0
 if test "$USE_BEOS" = 1; then

configure.in

@@ -4606,6 +4606,9 @@ AC_CHECK_FUNCS(timegm)
 
 dnl look for a function to modify the environment
 AC_CHECK_FUNCS(setenv putenv, break)
+if test "$ac_cv_func_setenv" = "yes"; then
+    AC_CHECK_FUNCS(unsetenv)
+fi
 
 HAVE_SOME_SLEEP_FUNC=0
 if test "$USE_BEOS" = 1; then

setup.h.in

@@ -1026,6 +1026,9 @@
 /* Define if you have the uname function.  */
 #undef HAVE_UNAME
 
+/* Define if you have the unsetenv function.  */
+#undef HAVE_UNSETENV
+
 /* Define if you have the <X11/XKBlib.h> header file.  */
 #undef HAVE_X11_XKBLIB_H
 

setup.h_vms

@@ -880,6 +880,7 @@ typedef pid_t GPid;
 /* Define if you have the setenv function.  */
 #   if __CRTL_VER >= 70000000
 #define HAVE_SETENV 1
+#define HAVE_UNSETENV 1
 #else
 #undef HAVE_SETENV
 #endif

src/unix/utilsunx.cpp

@@ -1098,6 +1098,15 @@ bool wxGetEnv(const wxString& var, wxString *value)
 static bool wxDoSetEnv(const wxString& variable, const char *value)
 {
 #if defined(HAVE_SETENV)
+    if ( !value )
+    {
+#ifdef HAVE_UNSETENV
+        return unsetenv(variable.mb_str()) == 0;
+#else
+        value = ""; // we can't pass NULL to setenv()
+#endif
+    }
+
     return setenv(variable.mb_str(), value, 1 /* overwrite */) == 0;
 #elif defined(HAVE_PUTENV)
     wxString s = variable;