+struct msg *
+msg_dup (const struct msg *src)
+{
+ struct msg_stack **ms = xmalloc (src->n_stack * sizeof *ms);
+ for (size_t i = 0; i < src->n_stack; i++)
+ ms[i] = msg_stack_dup (src->stack[i]);
+
+ struct msg *dst = xmalloc (sizeof *dst);
+ *dst = (struct msg) {
+ .category = src->category,
+ .severity = src->severity,
+ .stack = ms,
+ .n_stack = src->n_stack,
+ .location = msg_location_dup (src->location),
+ .command_name = xstrdup_if_nonnull (src->command_name),
+ .text = xstrdup (src->text),
+ };
+ return dst;
+}
+
+/* Frees a message created by msg_dup().
+
+ (Messages not created by msg_dup(), as well as their file_name
+ members, are typically not dynamically allocated, so this function should
+ not be used to destroy them.) */
+void
+msg_destroy (struct msg *m)
+{
+ if (m)
+ {
+ for (size_t i = 0; i < m->n_stack; i++)
+ msg_stack_destroy (m->stack[i]);
+ free (m->stack);
+ msg_location_destroy (m->location);
+ free (m->text);
+ free (m->command_name);
+ free (m);
+ }
+}
+
+char *
+msg_to_string (const struct msg *m)
+{
+ struct string s;
+
+ ds_init_empty (&s);
+
+ for (size_t i = 0; i < m->n_stack; i++)
+ {
+ const struct msg_stack *ms = m->stack[i];
+ if (!msg_location_is_empty (ms->location))
+ {
+ msg_location_format (ms->location, &s);
+ ds_put_cstr (&s, ": ");
+ }
+ ds_put_format (&s, "%s\n", ms->description);
+ }
+ if (m->category != MSG_C_GENERAL && !msg_location_is_empty (m->location))
+ {
+ msg_location_format (m->location, &s);
+ ds_put_cstr (&s, ": ");
+ }
+
+ ds_put_format (&s, "%s: ", msg_severity_to_string (m->severity));
+
+ if (m->category == MSG_C_SYNTAX && m->command_name != NULL)
+ ds_put_format (&s, "%s: ", m->command_name);
+
+ ds_put_cstr (&s, m->text);
+
+ return ds_cstr (&s);
+}
+\f
+
+/* Number of messages reported, by severity level. */
+static int counts[MSG_N_SEVERITIES];
+
+/* True after the maximum number of errors or warnings has been exceeded. */
+static bool too_many_errors;
+
+/* True after the maximum number of notes has been exceeded. */
+static bool too_many_notes;
+
+/* True iff warnings have been explicitly disabled (MXWARNS = 0) */
+static bool warnings_off = false;
+
+/* Checks whether we've had so many errors that it's time to quit
+ processing this syntax file. */
+bool
+msg_ui_too_many_errors (void)
+{
+ return too_many_errors;
+}
+
+void
+msg_ui_disable_warnings (bool x)
+{
+ warnings_off = x;
+}
+
+
+void
+msg_ui_reset_counts (void)
+{
+ int i;
+
+ for (i = 0; i < MSG_N_SEVERITIES; i++)
+ counts[i] = 0;
+ too_many_errors = false;
+ too_many_notes = false;
+}
+
+bool
+msg_ui_any_errors (void)
+{
+ return counts[MSG_S_ERROR] > 0;
+}
+
+
+static void
+ship_message (const struct msg *m)
+{
+ enum { MAX_STACK = 4 };
+ static const struct msg *stack[MAX_STACK];
+ static size_t n;
+
+ /* If we're recursing on a given message, or recursing deeply, drop it. */
+ if (n >= MAX_STACK)
+ return;
+ for (size_t i = 0; i < n; i++)
+ if (stack[i] == m)
+ return;
+
+ stack[n++] = m;
+ if (msg_handler && n <= 1)
+ msg_handler (m, msg_aux);
+ else
+ fprintf (stderr, "%s\n", m->text);
+ n--;
+}
+
+static void
+submit_note (char *s)
+{
+ struct msg m = {
+ .category = MSG_C_GENERAL,
+ .severity = MSG_S_NOTE,
+ .text = s,
+ };
+ ship_message (&m);
+
+ free (s);
+}
+
+static void
+process_msg (struct msg *m)