| use clippy_utils::diagnostics::span_lint_and_note; |
| use clippy_utils::ty::is_copy; |
| use rustc_hir::{Impl, Item, ItemKind}; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| use rustc_span::sym; |
| |
| use if_chain::if_chain; |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// Checks for types that implement `Copy` as well as |
| /// `Iterator`. |
| /// |
| /// ### Why is this bad? |
| /// Implicit copies can be confusing when working with |
| /// iterator combinators. |
| /// |
| /// ### Example |
| /// ```rust,ignore |
| /// #[derive(Copy, Clone)] |
| /// struct Countdown(u8); |
| /// |
| /// impl Iterator for Countdown { |
| /// // ... |
| /// } |
| /// |
| /// let a: Vec<_> = my_iterator.take(1).collect(); |
| /// let b: Vec<_> = my_iterator.collect(); |
| /// ``` |
| #[clippy::version = "1.30.0"] |
| pub COPY_ITERATOR, |
| pedantic, |
| "implementing `Iterator` on a `Copy` type" |
| } |
| |
| declare_lint_pass!(CopyIterator => [COPY_ITERATOR]); |
| |
| impl<'tcx> LateLintPass<'tcx> for CopyIterator { |
| fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) { |
| if_chain! { |
| if let ItemKind::Impl(Impl { |
| of_trait: Some(ref trait_ref), |
| .. |
| }) = item.kind; |
| let ty = cx.tcx.type_of(item.owner_id).instantiate_identity(); |
| if is_copy(cx, ty); |
| if let Some(trait_id) = trait_ref.trait_def_id(); |
| if cx.tcx.is_diagnostic_item(sym::Iterator, trait_id); |
| then { |
| span_lint_and_note( |
| cx, |
| COPY_ITERATOR, |
| item.span, |
| "you are implementing `Iterator` on a `Copy` type", |
| None, |
| "consider implementing `IntoIterator` instead", |
| ); |
| } |
| } |
| } |
| } |