print supported decoders in --version

src/cmdline.c

@@ -50,6 +50,10 @@ static void version(void)
 	decoder_plugin_print_all_suffixes(stdout);
 
 	puts("\n"
+	     "Supported decoders:\n");
+	decoder_plugin_print_all_decoders(stdout);
+
+	puts("\n"
 	     "Supported outputs:\n");
 	printAllOutputPluginTypes(stdout);
 

src/decoder_list.c

@@ -157,6 +157,19 @@ void decoder_plugin_print_all_suffixes(FILE * fp)
 	fflush(fp);
 }
 
+void decoder_plugin_print_all_decoders(FILE * fp)
+{
+	for (unsigned i = 0; i < num_decoder_plugins; ++i) {
+		const struct decoder_plugin *plugin = decoder_plugins[i];
+		if (!decoder_plugins_enabled[i])
+			continue;
+
+		fprintf(fp, "%s ", plugin->name);
+	}
+	fprintf(fp, "\n");
+	fflush(fp);
+}
+
 void decoder_plugin_init_all(void)
 {
 	for (unsigned i = 0; i < num_decoder_plugins; ++i) {

src/decoder_list.h

@@ -36,6 +36,8 @@ decoder_plugin_from_name(const char *name);
 
 void decoder_plugin_print_all_suffixes(FILE * fp);
 
+void decoder_plugin_print_all_decoders(FILE * fp);
+
 /* this is where we "load" all the "plugins" ;-) */
 void decoder_plugin_init_all(void);