{"html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fsecret-garden.hatenablog.com%2Fentry%2F2019%2F12%2F17%2F214936\" title=\"\u3010\u4e00\u4eba C++20 Advent Calendar 2019\u3011typeid \u304c constexpr \u306b\u5bfe\u5fdc\u301017\u65e5\u76ee\u3011 - Secret Garden(Instrumental)\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","height":"190","type":"rich","categories":["C++","C++20"],"title":"\u3010\u4e00\u4eba C++20 Advent Calendar 2019\u3011typeid \u304c constexpr \u306b\u5bfe\u5fdc\u301017\u65e5\u76ee\u3011","url":"https://secret-garden.hatenablog.com/entry/2019/12/17/214936","width":"100%","author_url":"https://blog.hatena.ne.jp/osyo-manga/","version":"1.0","published":"2019-12-17 21:49:36","author_name":"osyo-manga","blog_title":"Secret Garden(Instrumental)","provider_url":"https://hatena.blog","blog_url":"https://secret-garden.hatenablog.com/","image_url":null,"provider_name":"Hatena Blog","description":"\u4e00\u4eba C++20 Advent Calendar 2019 17\u65e5\u76ee\u306e\u8a18\u4e8b\u306b\u306a\u308a\u307e\u3059\u3002 typeid \u304c constexpr \u306b\u5bfe\u5fdc \u6628\u65e5\u66f8\u3044\u305f dynamic_cast \u304c constexpr \u306b\u5bfe\u5fdc\u3057\u305f\u306e\u306b\u5408\u308f\u305b\u3066 type_id \u3082 constexpr \u306b\u5bfe\u5fdc\u3057\u307e\u3057\u305f\u3002 #include <typeinfo> #include <iostream> struct A { virtual void dummy() {} }; struct B { virtual void dummy() {} }; int main(){ constexpr A a1{}; constexpr A a2{\u2026"}