{"url":"https://hiratara.hatenadiary.jp/entry/2020/08/05/161623","description":"\u30c8\u30ec\u30a4\u30c8\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u8fd4\u3059\u6b21\u306e\u95a2\u6570 f \u306f\u30b3\u30f3\u30d1\u30a4\u30eb\u3067\u304d\u308b\u3002 trait X {} fn f(x: &dyn X) -> &dyn X { x } \u3068\u3053\u308d\u304c\u3001\u6b21\u306e\u3088\u3046\u306b\u66f8\u304f\u3068\u30b3\u30f3\u30d1\u30a4\u30eb\u3067\u304d\u306a\u3044\u3002 fn f<T: X + ?Sized>(x: &T) -> &dyn X { x } Compiling playground v0.0.1 (/playground) error[E0277]: the size for values of type `T` cannot be known at compilation time --> src/lib.rs:4:5 | 3 | fn f<T: X \u2026","width":"100%","categories":["\u6280\u8853"],"author_url":"https://blog.hatena.ne.jp/hiratara/","title":"&T\u304c\u305d\u306e\u307e\u307e&dyn Trait\u3068\u3057\u3066\u4f7f\u3048\u308b\u308f\u3051\u3067\u306f\u306a\u3044","blog_url":"https://hiratara.hatenadiary.jp/","provider_name":"Hatena Blog","published":"2020-08-05 16:16:23","author_name":"hiratara","provider_url":"https://hatena.blog","version":"1.0","type":"rich","blog_title":"Pixel Pedals of Tomakomai","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fhiratara.hatenadiary.jp%2Fentry%2F2020%2F08%2F05%2F161623\" title=\"&amp;T\u304c\u305d\u306e\u307e\u307e&amp;dyn Trait\u3068\u3057\u3066\u4f7f\u3048\u308b\u308f\u3051\u3067\u306f\u306a\u3044 - Pixel Pedals of Tomakomai\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","image_url":null,"height":"190"}