options: clean up the parser, prepare for new options with no short form

We're not adding any more short options, but the debugging code doesn't
work with optvals above 255.  Also clean up constness and variable
lifetimes.

Signed-off-by: Zygo Blaxell <bees@furryterror.org>

src/bees.cc

@@ -735,10 +735,10 @@ bees_main(int argc, char *argv[])
 	// Build getopt_long's short option list from the long_options table.
 	// While we're at it, make sure we didn't duplicate any options.
 	string getopt_list;
-	set<decltype(option::val)> option_vals;
+	map<decltype(option::val), string> option_vals;
 	for (const struct option *op = long_options; op->val; ++op) {
-		THROW_CHECK1(runtime_error, op->val, !option_vals.count(op->val));
-		option_vals.insert(op->val);
+		const auto ins_rv = option_vals.insert(make_pair(op->val, op->name));
+		THROW_CHECK1(runtime_error, op->val, ins_rv.second);
 		if ((op->val & 0xff) != op->val) {
 			continue;
 		}
@@ -749,16 +749,17 @@ bees_main(int argc, char *argv[])
 	}
 
 	// Parse options
-	int c;
 	while (true) {
 		int option_index = 0;
 
-		c = getopt_long(argc, argv, getopt_list.c_str(), long_options, &option_index);
+		const auto c = getopt_long(argc, argv, getopt_list.c_str(), long_options, &option_index);
 		if (-1 == c) {
 			break;
 		}
 
-		BEESLOGDEBUG("Parsing option '" << static_cast<char>(c) << "'");
+		// getopt_long should have weeded out any invalid options,
+		// so we can go ahead and throw here
+		BEESLOGDEBUG("Parsing option '" << option_vals.at(c) << "'");
 
 		switch (c) {