+dnl Use -v and some other options with SunStudio cc.
+AS_CASE([`${CC} -V 2>&1`],
+ [cc:\ Sun\ C*], [CFLAGS="${CFLAGS:+$CFLAGS }-v -errtags=yes"
+ CFLAGS="${CFLAGS} -erroff=E_STATEMENT_NOT_REACHED"])
+
+AC_CACHE_CHECK([whether compiler supports -Wextra], [nmh_cv_has_wextra],
+[nmh_saved_cflags="$CFLAGS"
+ CFLAGS="$CFLAGS -Wextra -Werror"
+ AC_TRY_COMPILE([],[],nmh_cv_has_wextra=yes,nmh_cv_has_wextra=no)
+ CFLAGS="$nmh_saved_cflags"])
+
+dnl Can't use -ansi with gcc 4.5.3 on Cygwin, at least through setup
+dnl version 2.763, because it disables some features in the system
+dnl header files and warns about them with -Wall. Try to test for
+dnl that generally, though still with gcc.
+if test "$GCC" = yes; then
+ AC_CACHE_CHECK([whether we can use -ansi with gcc], [nmh_cv_has_dash_ansi],
+ [nmh_saved_cppflags="$CPPFLAGS"
+ nmh_saved_cflags="$CFLAGS"
+ CPPFLAGS="-D_GNU_SOURCE"
+ CFLAGS="-ansi -Wall -Werror"
+ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <time.h>],[tzset();])],
+ [nmh_cv_has_dash_ansi=yes],
+ [nmh_cv_has_dash_ansi=no])
+ CPPFLAGS="$nmh_saved_cppflags"
+ CFLAGS="$nmh_saved_cflags"])
+else
+ nmh_cv_has_dash_ansi=no
+fi
+
+dnl if the user hasn't specified CFLAGS, then
+dnl if compiler is gcc, then
+dnl use -O2 and some warning flags
+dnl else use -O
+dnl We use -Wall and -Wextra if supported. If the compiler supports it we
+dnl also use -Wno-pointer-sign, because gcc 4 now produces a lot of new
+dnl warnings which are probably mostly spurious and which in any case we
+dnl don't want to deal with now.
+if test "$nmh_cv_has_dash_ansi" = "yes"; then
+ nmh_gcc_warnflags="-ansi -pedantic -Wall"
+else
+ nmh_gcc_warnflags="-Wall"
+fi
+if test "$nmh_cv_has_wextra" = "yes"; then
+ nmh_gcc_warnflags="${nmh_gcc_warnflags} -Wextra"
+fi
+