rust-lang/rust-clippy

New lint: Use `Into`/`TryInto` in bounds as opposed to `From`/`TryFrom`

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#4,894 建立於 2019年12月10日

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 (29 留言) (1 反應) (0 負責人)Rust (10,406 star) (1,391 fork)batch import
A-lintL-stylegood first issue

描述

When writing generic bounds such as:

fn foo<T>(a: T) where u32: From<T>;

Into should be preferred, like this:

fn foo<T>(a: T) where T: Into<u32>;

Why the former is bad: Into is a superset of From. In some cases coherence rules prevent implementing From but do allow implementing Into. As a result Into is more generic bound than From.

Category: Style, I guess?

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feature
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Basic RustUnderstanding of trait boundsClippy development setup
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研究方向
Study the Clippy developer guide for adding a new lint. Look at existing lints that suggest trait usage, such as the 'trait usage' lints in clippy lints/src/. The issue comments may contain further rationale; review them for consensus on exact implementation. The lint should detect generic bounds like `u32: From<T>` and suggest replacing with `T: Into<u32>`. Explore the clippy lints crate to understand naming conventions and testing patterns.
New lint: Use `Into`/`TryInto` in bounds as opposed to `From`/`TryFrom` · rust-lang/rust-clippy#4894 | Good First Issue