From b4463e8b84a227e8bbed854dcaab02aad4bd801f Mon Sep 17 00:00:00 2001
From: hyung-hwan <hyunghwan.chung@gmail.com>
Date: Sat, 30 Jun 2018 03:48:37 +0000
Subject: [PATCH] enhanced the __int128_t check with extra check against va_arg

---
 configure    | 8 +++++---
 configure.ac | 6 ++++--
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/configure b/configure
index ffb3bca..6f7fa10 100755
--- a/configure
+++ b/configure
@@ -20395,16 +20395,18 @@ fi
 
 if test ${ac_cv_sizeof___int128_t} -gt 0
 then
-	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking __int128_t with %" >&5
-$as_echo_n "checking __int128_t with %... " >&6; }
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking __int128_t with % and va_arg" >&5
+$as_echo_n "checking __int128_t with % and va_arg... " >&6; }
 	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
-
+#include <stdarg.h>
 int
 main ()
 {
 
 			volatile __int128_t x, base;
+			va_list ap;
+			va_list (ap, __int128_t);
 			x = (__int128_t)&base;
 			base = (__int128_t)&x;
 			x = x % base;
diff --git a/configure.ac b/configure.ac
index a1a38d6..740ce67 100644
--- a/configure.ac
+++ b/configure.ac
@@ -394,10 +394,12 @@ dnl Changing ac_cv_sizeof___int128_t here doesn't corret SIZEOF___INT128_T
 dnl since it's already generated. It only affects HCL_SIZEOF___INT128_T below.
 if test ${ac_cv_sizeof___int128_t} -gt 0
 then
-	AC_MSG_CHECKING([__int128_t with %])
+	AC_MSG_CHECKING([__int128_t with % and va_arg])
 	AC_COMPILE_IFELSE(
-		[AC_LANG_PROGRAM([], [
+		[AC_LANG_PROGRAM([#include <stdarg.h>], [
 			volatile __int128_t x, base;
+			va_list ap;
+			va_list (ap, __int128_t);
 			x = (__int128_t)&base;
 			base = (__int128_t)&x;
 			x = x % base;