Small refactoring: should use RSTR_CAPA
MODIFY
src/string.c
src/string.c
@@ -154,10 +154,7 @@ str_buf_cat(mrb_state *mrb, struct RString *s, const char *ptr, size_t len)
off = ptr - RSTR_PTR(s);
}
- if (RSTR_EMBED_P(s))
- capa = RSTRING_EMBED_LEN_MAX;
- else
- capa = s->as.heap.aux.capa;
+ capa = RSTR_CAPA(s);
if (capa <= RSTRING_EMBED_LEN_MAX)
capa = RSTRING_EMBED_LEN_MAX+1;

Small refactoring: should use RSTR_CAPA