56 lines
1.7 KiB
Rust
56 lines
1.7 KiB
Rust
use crate::utils::{is_copy, match_path, paths, span_lint_and_note};
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use rustc_hir::{Item, ItemKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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declare_clippy_lint! {
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/// **What it does:** Checks for types that implement `Copy` as well as
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/// `Iterator`.
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///
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/// **Why is this bad?** Implicit copies can be confusing when working with
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/// iterator combinators.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust,ignore
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/// #[derive(Copy, Clone)]
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/// struct Countdown(u8);
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///
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/// impl Iterator for Countdown {
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/// // ...
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/// }
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///
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/// let a: Vec<_> = my_iterator.take(1).collect();
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/// let b: Vec<_> = my_iterator.collect();
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/// ```
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pub COPY_ITERATOR,
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pedantic,
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"implementing `Iterator` on a `Copy` type"
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}
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declare_lint_pass!(CopyIterator => [COPY_ITERATOR]);
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CopyIterator {
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fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item<'_>) {
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if let ItemKind::Impl {
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of_trait: Some(ref trait_ref),
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..
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} = item.kind
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{
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let ty = cx.tcx.type_of(cx.tcx.hir().local_def_id(item.hir_id));
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if is_copy(cx, ty) && match_path(&trait_ref.path, &paths::ITERATOR) {
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span_lint_and_note(
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cx,
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COPY_ITERATOR,
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item.span,
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"you are implementing `Iterator` on a `Copy` type",
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None,
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"consider implementing `IntoIterator` instead",
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);
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}
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}
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}
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}
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