+AC_CACHE_CHECK([whether preprocessor supports -Wunused-macros],
+ [nmh_cv_has_unusedmacros],
+ [nmh_saved_cppflags="$CPPFLAGS"
+ CPPFLAGS="$CPPFLAGS -Wunused-macros -Wno-unused-macros"
+ AC_TRY_COMPILE([],[],nmh_cv_has_unusedmacros=yes,nmh_cv_has_unusedmacros=no)
+ CPPFLAGS="$nmh_saved_cppflags"])
+
+if test "$nmh_cv_has_unusedmacros" = 'yes'; then
+ test -z "$CPPFLAGS" && CPPFLAGS=-Wunused-macros \
+ || CPPFLAGS="$CPPFLAGS -Wunused-macros"
+ DISABLE_UNUSED_MACROS_WARNING=-Wno-unused-macros
+fi
+AC_SUBST(DISABLE_UNUSED_MACROS_WARNING)dnl
+
+AC_CACHE_CHECK([whether compiler supports -Wno-sign-compare],
+ [nmh_cv_has_nosigncompare],
+ [nmh_saved_cppflags="$CPPFLAGS"
+ CPPFLAGS="$CPPFLAGS -Wno-sign-compare"
+ AC_TRY_COMPILE([],[],nmh_cv_has_nosigncompare=yes,
+ nmh_cv_has_nosigncompare=no)
+ CPPFLAGS="$nmh_saved_cppflags"])
+
+if test "$nmh_cv_has_nosigncompare" = 'yes'; then
+ DISABLE_SIGN_COMPARE_WARNING=-Wno-sign-compare
+fi
+AC_SUBST(DISABLE_SIGN_COMPARE_WARNING)dnl
+
+AC_CACHE_CHECK([whether compiler supports -Wextra], [nmh_cv_has_wextra],
+[nmh_saved_cflags="$CFLAGS"
+ CFLAGS="$CFLAGS -Wextra -Wno-clobbered"
+ AC_TRY_COMPILE([],[],nmh_cv_has_wextra=yes,nmh_cv_has_wextra=no)
+ CFLAGS="$nmh_saved_cflags"])
+
+AC_CACHE_CHECK([whether compiler supports -Wno-pointer-sign], [nmh_cv_has_noptrsign],