use mrb_str_cat_str() instead of mrb_str_append()

If the argument is always a string, then mrb_str_cat_str() can be
directly called instead of indirectly by mrb_str_append().

mrb_any_to_s(), mrb_obj_as_string(), mrb_inspect() always return a
string.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/error.c b/src/error.c
index 20c63bd43..359e5737b 100644
--- a/src/error.c
+++ b/src/error.c
@@ -152,7 +152,7 @@ exc_inspect(mrb_state *mrb, mrb_value exc)
     mrb_str_append(mrb, str, line);
     mrb_str_cat_lit(mrb, str, ": ");
     if (append_mesg) {
-      mrb_str_append(mrb, str, mesg);
+      mrb_str_cat_str(mrb, str, mesg);
       mrb_str_cat_lit(mrb, str, " (");
     }
     mrb_str_cat_cstr(mrb, str, mrb_obj_classname(mrb, exc));
@@ -165,7 +165,7 @@ exc_inspect(mrb_state *mrb, mrb_value exc)
     str = mrb_str_new_cstr(mrb, cname);
     mrb_str_cat_lit(mrb, str, ": ");
     if (append_mesg) {
-      mrb_str_append(mrb, str, mesg);
+      mrb_str_cat_str(mrb, str, mesg);
     }
     else {
       mrb_str_cat_cstr(mrb, str, cname);