configure: check for sync-nand

Check whether gcc support this flag.
Some older compilers (gcc version 4.3.2) miss it.

configure

@@ -749,6 +749,7 @@ CUNIT_CFLAGS
 GENPNG
 GENHTML
 LCOV
+HAVE_WSYNCNAND
 HAVE_WCLOBBERED
 HAVE_WJUMP
 SACKPT_LIBS
@@ -10214,6 +10215,44 @@ $as_echo "$ac_cv_flag_HAVE_WCLOBBERED" >&6; }
 
 
 
+
+    ac_save_CFLAGS=$CFLAGS
+    CFLAGS=-Wsync-nand
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC accepts -Wsync-nand flag" >&5
+$as_echo_n "checking whether $CC accepts -Wsync-nand flag... " >&6; }
+if ${ac_cv_flag_HAVE_WSYNCNAND+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  ac_cv_flag_HAVE_WSYNCNAND=yes
+else
+  ac_cv_flag_HAVE_WSYNCNAND=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_flag_HAVE_WSYNCNAND" >&5
+$as_echo "$ac_cv_flag_HAVE_WSYNCNAND" >&6; }
+    CFLAGS=$ac_save_CFLAGS
+    HAVE_WSYNCNAND=$ac_cv_flag_HAVE_WSYNCNAND
+    if test "HAVE_WSYNCNAND" = yes; then
+        :
+    else
+        :
+    fi
+
+
+
 ################################################################################
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for C optimisation flag" >&5
 $as_echo_n "checking for C optimisation flag... " >&6; }

configure.in

@@ -962,6 +962,8 @@ AC_TRY_CCFLAG([-Wjump-misses-init], [HAVE_WJUMP], [], [])
 AC_SUBST(HAVE_WJUMP)
 AC_TRY_CCFLAG([-Wclobbered], [HAVE_WCLOBBERED], [], [])
 AC_SUBST(HAVE_WCLOBBERED)
+AC_TRY_CCFLAG([-Wsync-nand], [HAVE_WSYNCNAND], [], [])
+AC_SUBST(HAVE_WSYNCNAND)
 
 ################################################################################
 dnl -- Override optimisation

make.tmpl.in

@@ -156,7 +156,11 @@ endif
 ifeq ("@HAVE_WCLOBBERED@", "yes")
 WFLAGS += -Wclobbered -Wempty-body -Wignored-qualifiers \
  -Wmissing-parameter-type -Wold-style-declaration -Woverride-init \
- -Wtype-limits -Wsync-nand -Wlogical-op
+ -Wtype-limits -Wlogical-op
+endif
+
+ifeq ("@HAVE_WSYNCNAND@", "yes")
+WFLAGS += -Wsync-nand
 endif
 
 ifneq ("@STATIC_LINK@", "yes")