Build of glibmm24-2.47.4-2.fc24 fails on s390(x) with gcc-c++-6.0.0-0.14.fc24 with an error, while it succeeds elsewhere.

from build.log at http://s390.koji.fedoraproject.org/koji/taskinfo?taskID=2135162

...
libtool: compile:  g++ -DHAVE_CONFIG_H -I.. -I../.. -DG_LOG_DOMAIN=\"glibmm\" -DGLIBMM_BUILD=1 -pthread -I/usr/include/sigc++-2.0 -I/usr/lib64/sigc++-2.0/include -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -Wall -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -march=z9-109 -mtune=z10 -c object.cc  -fPIC -DPIC -o .libs/object.o
In file included from /usr/include/glib-2.0/glib/gerror.h:27:0,
                 from /usr/include/glib-2.0/glib/gthread.h:33,
                 from /usr/include/glib-2.0/glib/gasyncqueue.h:32,
                 from /usr/include/glib-2.0/glib.h:32,
                 from /usr/include/glib-2.0/gobject/gbinding.h:28,
                 from /usr/include/glib-2.0/glib-object.h:23,
                 from ../glibmm/class.h:25,
                 from ../glibmm/objectbase.h:22,
                 from ../glibmm/object.h:28,
                 from object.cc:18:
object.cc: In constructor 'Glib::ConstructParams::ConstructParams(const Glib::Class&, const char*, ...)':
/usr/include/glib-2.0/gobject/gvaluecollector.h:105:41: error: first argument to 'va_arg' not of type 'va_list'
    _cvalue->v_int = va_arg ((var_args), gint);     \
                     ~                    
/usr/include/glib-2.0/gobject/gvaluecollector.h:156:3: note: in expansion of macro 'G_VALUE_COLLECT_INIT'
   G_VALUE_COLLECT_INIT(value, _value_type, var_args, flags, __error);   \
   ^~~~~~~~~~~~~~~~~~~~
object.cc:109:5: note: in expansion of macro 'G_VALUE_COLLECT'
     G_VALUE_COLLECT(&param.value, var_args, 0, &collect_error);
     ^~~~~~~~~~~~~~~
/usr/include/glib-2.0/gobject/gvaluecollector.h:108:42: error: first argument to 'va_arg' not of type 'va_list'
    _cvalue->v_long = va_arg ((var_args), glong);     \
                      ~                    
/usr/include/glib-2.0/gobject/gvaluecollector.h:156:3: note: in expansion of macro 'G_VALUE_COLLECT_INIT'
   G_VALUE_COLLECT_INIT(value, _value_type, var_args, flags, __error);   \
   ^~~~~~~~~~~~~~~~~~~~
object.cc:109:5: note: in expansion of macro 'G_VALUE_COLLECT'
     G_VALUE_COLLECT(&param.value, var_args, 0, &collect_error);
     ^~~~~~~~~~~~~~~
/usr/include/glib-2.0/gobject/gvaluecollector.h:111:43: error: first argument to 'va_arg' not of type 'va_list'
    _cvalue->v_int64 = va_arg ((var_args), gint64);    \
                       ~                    
/usr/include/glib-2.0/gobject/gvaluecollector.h:156:3: note: in expansion of macro 'G_VALUE_COLLECT_INIT'
   G_VALUE_COLLECT_INIT(value, _value_type, var_args, flags, __error);   \
   ^~~~~~~~~~~~~~~~~~~~
object.cc:109:5: note: in expansion of macro 'G_VALUE_COLLECT'
     G_VALUE_COLLECT(&param.value, var_args, 0, &collect_error);
     ^~~~~~~~~~~~~~~
/usr/include/glib-2.0/gobject/gvaluecollector.h:114:44: error: first argument to 'va_arg' not of type 'va_list'
    _cvalue->v_double = va_arg ((var_args), gdouble);    \
                        ~                    
/usr/include/glib-2.0/gobject/gvaluecollector.h:156:3: note: in expansion of macro 'G_VALUE_COLLECT_INIT'
   G_VALUE_COLLECT_INIT(value, _value_type, var_args, flags, __error);   \
   ^~~~~~~~~~~~~~~~~~~~
object.cc:109:5: note: in expansion of macro 'G_VALUE_COLLECT'
     G_VALUE_COLLECT(&param.value, var_args, 0, &collect_error);
     ^~~~~~~~~~~~~~~
/usr/include/glib-2.0/gobject/gvaluecollector.h:117:45: error: first argument to 'va_arg' not of type 'va_list'
    _cvalue->v_pointer = va_arg ((var_args), gpointer);    \
                         ~                    
/usr/include/glib-2.0/gobject/gvaluecollector.h:156:3: note: in expansion of macro 'G_VALUE_COLLECT_INIT'
   G_VALUE_COLLECT_INIT(value, _value_type, var_args, flags, __error);   \
   ^~~~~~~~~~~~~~~~~~~~
object.cc:109:5: note: in expansion of macro 'G_VALUE_COLLECT'
     G_VALUE_COLLECT(&param.value, var_args, 0, &collect_error);
     ^~~~~~~~~~~~~~~
Makefile:744: recipe for target 'object.lo' failed


The source source is https://git.gnome.org/browse/glibmm/tree/glib/glibmm/object.cc?id=42a47cb78e4815da6d6ebccafda864326fcdd22c#n69
and then https://git.gnome.org/browse/glib/tree/gobject/gvaluecollector.h?h=2.47.5#n88

I have reduced the code and I'm getting an error on s390x, but not on x86_64

[sharkcz@devel10 glibmm]$ cat a.cc
#include <cstdarg>

class A
{
public:
    A(const char* f, ...);
};

A::A(const char *f, ...)
{
  va_list var_args;
  va_start(var_args, f);

  int i;
  i = va_arg ((var_args), int);

  va_end(var_args);
}
[sharkcz@devel10 glibmm]$ g++ -Wall -O2 -Wall -c a.cc -o a.o
a.cc: In constructor ‘A::A(const char*, ...)’:
a.cc:14:7: warning: variable ‘i’ set but not used [-Wunused-but-set-variable]
   int i;
       ^
In file included from /usr/include/c++/6.0.0/cstdarg:43:0,
                 from a.cc:1:
a.cc: In constructor ‘A::A(const char*, ...)’:
a.cc:15:27: error: first argument to ‘va_arg’ not of type ‘va_list’
   i = va_arg ((var_args), int);
       ~                    
[sharkcz@devel10 glibmm]$ rpm -q gcc-c++
gcc-c++-6.0.0-0.14.fc24.s390x


while compile on x86_64 returns:

<mock-chroot>sh-4.3# g++ -Wall -O2 -Wall -c a.cc -o a.o
a.cc: In constructor 'A::A(const char*, ...)':
a.cc:14:7: warning: variable 'i' set but not used [-Wunused-but-set-variable]
   int i;
       ^
<mock-chroot>sh-4.3# rpm -q gcc-c++
gcc-c++-6.0.0-0.13.fc24.x86_64