AI代码解释 error[E0038]:the trait`Clone`cannot be made into an object-->src/main.rs:31:14|31|fnte(x:Box<dyn Clone>){|^^^^^^^^^`Clone`cannot be made into an object|=note:the trait cannot be made into an object beca
the traitHellocannot be made into an object… because associated functionweirdhas noselfparameter 同时,编译器还给了提示,要么给weird函数加上self,要么限制weird函数,使其不再适用于trait object,即 fn weird() where Self: Sized {} 此时,我们不再能通过一个&dyn Hello类型的变量来调用weird,因为它不在vtab...
traitStringSet{fnnew()->Self;fnhas(&self,s:&str)->bool;fnadd(&self,s:&str);}fnf(s:&StringSet){s.add("hello");}fnmain(){} This isn't allowed: rustc 1.16.0 (30cf806ef 2017-03-10)error[E0038]: the trait `StringSet` cannot be made into an object--> <anon>:7:1|7 |...
2 | 3 | fn function(t: &dyn Trait) {} | ^^^ the trait `Trait` cannot be made into an object Let's try to make an ?Sized trait with a Sized method and see if we can cast it to a trait object:trait Trait { fn method(self) where Self: Sized {} fn method2(&self) {} ...
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/// The filesystem object is, unexpectedly, a directory. /// /// A directory was specified when a non-directory was expected. #[unstable(feature ="io_error_more", issue ="86442")] IsADirectory, /// A non-empty directory was specified where an empty directory was expected. ...
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重新借用可变引用不会结束其生命周期,即使该引用已被 drop 掉 每种语言皆有陷阱 🤷 rust 本文系翻译,阅读原文 https://github.com/pretzelhammer/rust-blog/blob/master/posts/common-rust-lifetime-misconceptions.md 阅读981更新于2023-11-08 Qiang
The second condition is thatTitself must besized. This is less obvious and perhaps a bit unfortunate, as it means that even if a type like[int]implementsTrait, we cannot create an object from it. This is for implementation reasons: the representation of an object is always(pointer, vtable...
(and in the general case, garbage collection). C++ keeps the ownership of all the memory clear, at the expense of making assignment carry out a deep copy of the object. C++ programmers are often less than enthusiastic about this choice: deep copies can be expensive, and there are usually ...