+/** Whether -Werror was set. */
+extern bool warnings_are_errors;
+
+/** Decode a single argument from -W.
+ *
+ * \param arg the subarguments to decode.
+ * If null, then activate all the flags.
+ * \param no length of the potential "no-" prefix.
+ * Can be 0 or 3. If 3, negate the action of the subargument.
+ * \param err length of a potential "error=".
+ * Can be 0 or 6. If 6, treat the subargument as a CATEGORY.
+ *
+ * If VALUE != 0 then KEY sets flags and no-KEY clears them.
+ * If VALUE == 0 then KEY clears all flags from \c all and no-KEY sets all
+ * flags from \c all. Thus no-none = all and no-all = none.
+ */
+void warning_argmatch (char const *arg, size_t no, size_t err);
+
+/** Decode a comma-separated list of arguments from -W.
+ *
+ * \param args comma separated list of effective subarguments to decode.
+ * If 0, then activate all the flags.
+ */
+void warnings_argmatch (char *args);
+
+
+/*-----------.
+| complain. |
+`-----------*/
+
+/** Initialize this module. */
+void complain_init (void);
+