+ if (argv[i][0] == '+' && argv[i][1] == '\0') {
+ fprintf (stderr, "Error: tag names cannot be empty.\n");
+ return 1;
+ }
+ if (argv[i][0] == '+' && argv[i][1] == '-') {
+ /* This disallows adding the non-removable tag "-" and
+ * enables notmuch tag to take long options in the
+ * future. */
+ fprintf (stderr, "Error: tag names must not start with '-'.\n");
+ return 1;
+ }