rust-lang/rust-clippy
Ver no GitHubrc_buffer lint is dangerous as it changes runtime behaviour
Open
#6.170 aberto em 13 de out. de 2020
C-bugL-suggestiongood first issue
Métricas do repositório
- Stars
- (10.406 stars)
- Métricas de merge de PR
- (Mesclagem média 19d 22h) (113 fundiu PRs em 30d)
Description
clippy warns if one tries to use a type like Rc<Vec<T>>, e.g.
Arc<Vec<u8>>
^^^^^^^^^^^^ help: try: `Arc<[u8]>`
This is dangerous as creating a Rc<[T]> causes a memcpy of the whole memory area with all the elements, while creating an Rc<Vec<T>> simply copies over the 3 pointers inside the Vec without copying all the elements.
A better suggestion would probably be Rc<Box<[T]>> as that has the same runtime behaviour, but even independent of that it can be useful to have a Vec inside an Rc / Arc in combination with the make_mut() / get_mut() API.
The lint should probably be at least disabled by default.
The same also applies to Rc<String> vs Rc<str>.