Michael Howell dbd4fd5716 feat(rustc_lint): add dyn_drop ... Based on the conversation in #86747. Explanation ----------- A trait object bound of the form `dyn Drop` is most likely misleading and not what the programmer intended. `Drop` bounds do not actually indicate whether a type can be trivially dropped or not, because a composite type containing `Drop` types does not necessarily implement `Drop` itself. Naïvely, one might be tempted to write a deferred drop system, to pull cleaning up memory out of a latency-sensitive code path, using `dyn Drop` trait objects. However, this breaks down e.g. when `T` is `String`, which does not implement `Drop`, but should probably be accepted. To write a trait object bound that accepts anything, use a placeholder trait with a blanket implementation. ```rust trait Placeholder {} impl<T> Placeholder for T {} fn foo(_x: Box<dyn Placeholder>) {} ```		2021-07-18 07:55:57 -07:00
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src	feat(rustc_lint): add dyn_drop	2021-07-18 07:55:57 -07:00
Cargo.toml	Add --extern-loc to augment unused crate dependency diagnostics	2021-02-07 14:54:20 -08:00