Fix the underlying non-literal-null-conversion instead of suppressing

The warning. What it was warning about was two calls to "g_strdup(NULL);",
which is a really dumb way of saying "NULL".

configure.ac

@@ -1323,9 +1323,6 @@ AX_CHECK_COMPILE_FLAG([-Wno-deprecated-register],
     [AM_CXXFLAGS="${AM_CXXFLAGS} -Wno-unused -Wno-deprecated-register"],
     [AM_CXXFLAGS="${AM_CXXFLAGS} -Wno-unused"], [-Werror])
 AC_LANG([C])
-AX_CHECK_PREPROC_FLAG([-Wno-non-literal-null-conversion],
-    [AM_CPPFLAGS="${AM_CPPFLAGS} -Wno-non-literal-null-conversion"],
-    [], [-Werror])
 AC_MSG_CHECKING(what extra warning flags to pass to the C compiler)
 if test ${GCC}x = yesx
 then

macros/ax_check_preproc_flag.m4

@@ -1,74 +0,0 @@
-# ===========================================================================
-#   http://www.gnu.org/software/autoconf-archive/ax_check_preproc_flag.html
-# ===========================================================================
-#
-# SYNOPSIS
-#
-#   AX_CHECK_PREPROC_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
-#
-# DESCRIPTION
-#
-#   Check whether the given FLAG works with the current language's
-#   preprocessor or gives an error.  (Warnings, however, are ignored)
-#
-#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
-#   success/failure.
-#
-#   If EXTRA-FLAGS is defined, it is added to the preprocessor's default
-#   flags when the check is done.  The check is thus made with the flags:
-#   "CPPFLAGS EXTRA-FLAGS FLAG".  This can for example be used to force the
-#   preprocessor to issue an error when a bad flag is given.
-#
-#   INPUT gives an alternative input source to AC_PREPROC_IFELSE.
-#
-#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
-#   macro in sync with AX_CHECK_{COMPILE,LINK}_FLAG.
-#
-# LICENSE
-#
-#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
-#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
-#
-#   This program is free software: you can redistribute it and/or modify it
-#   under the terms of the GNU General Public License as published by the
-#   Free Software Foundation, either version 3 of the License, or (at your
-#   option) any later version.
-#
-#   This program is distributed in the hope that it will be useful, but
-#   WITHOUT ANY WARRANTY; without even the implied warranty of
-#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
-#   Public License for more details.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <http://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
-
-#serial 3
-
-AC_DEFUN([AX_CHECK_PREPROC_FLAG],
-[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
-AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]cppflags_$4_$1])dnl
-AC_CACHE_CHECK([whether _AC_LANG preprocessor accepts $1], CACHEVAR, [
-  ax_check_save_flags=$CPPFLAGS
-  CPPFLAGS="$CPPFLAGS $4 $1"
-  AC_PREPROC_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
-    [AS_VAR_SET(CACHEVAR,[yes])],
-    [AS_VAR_SET(CACHEVAR,[no])])
-  CPPFLAGS=$ax_check_save_flags])
-AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
-  [m4_default([$2], :)],
-  [m4_default([$3], :)])
-AS_VAR_POPDEF([CACHEVAR])dnl
-])dnl AX_CHECK_PREPROC_FLAGS

src/gnome-utils/gnc-tree-view-split-reg.c

@@ -5306,7 +5306,7 @@ gtv_sr_type_cb (GtkEntry    *entry,
         {
             /* If it's not there (or the list is empty) use default_flag */
             g_free (result);
-            result  = g_strdup (TXN_TYPE_NONE);
+            result  = NULL;
         }
     }
     else

src/register/ledger-core/split-register-model.c

@@ -1074,7 +1074,7 @@ gnc_split_register_get_vnotes_entry (VirtualLocation virt_loc,
     trans = xaccSplitGetParent (split);
 
     if(trans == NULL)
-        return g_strdup('\0');
+        return NULL;
     else 
         return xaccTransGetVoidReason(trans);
 }