Added descriptions for logging levels

Fortune for naka's current commit: Half blessing − 半吉

include/trace.h

@@ -31,5 +31,7 @@ int trace_init();
 const char* trace_name_of(enum trace_level lv);
 
 extern const char* const _TRACE_CONTROL_ENV_NAME;
+extern const char* const _trace_level_descriptions[_TRACE_LEVEL_NUM];
+
 
 #endif /* _TRACE_H */

src/main.c

@@ -23,7 +23,10 @@ static void pi_print_trace_infos(FILE* out)
 		enum trace_level lv = (enum trace_level)i;
 		name = trace_name_of(lv);
 		if(name) {
-			fprintf(out, "-> level %d: \"%s\"\n", i, name);
+			debug_assert(AS(lv, int) < AS(_TRACE_LEVEL_NUM, int) && AS(lv, int) >= 0);
+			const char* desc = lv[_trace_level_descriptions];
+			assert(desc);
+			fprintf(out, "-> level %d: \"%s\" - %s\n", i, name, desc);
 		}
 	}
 	enum trace_level def = _TRACE_LEVEL_DEFAULT;

src/trace.c

@@ -27,6 +27,14 @@ const struct {const char* const name; const enum trace_level level; } _trace_lev
 };
 #define _trace_level_names_n (sizeof(_trace_level_names) / sizeof(_trace_level_names[0]))
 
+const char* const _trace_level_descriptions[_TRACE_LEVEL_NUM] = {
+	"All trace messages regarding internals, only useful for debugging",
+	"Information messages regarding processes, recommended level",
+	"Only show warnings",
+	"Only show errors",
+	"Only show fatal (aborting) errors",
+};
+
 
 static bool _trace_lookup(const char*pIN name, enum trace_level *pOUT olevel)
 {