efca32e23a
spastorino noticed some silly expressions like `item_id.def_id.def_id`. This commit renames several `def_id: OwnerId` fields as `owner_id`, so those expressions become `item_id.owner_id.def_id`. `item_id.owner_id.local_def_id` would be even clearer, but the use of `def_id` for values of type `LocalDefId` is *very* widespread, so I left that alone.
63 lines
1.8 KiB
Rust
63 lines
1.8 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_note;
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use clippy_utils::ty::is_copy;
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use rustc_hir::{Impl, 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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use rustc_span::sym;
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use if_chain::if_chain;
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declare_clippy_lint! {
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/// ### What it does
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/// 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?
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/// Implicit copies can be confusing when working with
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/// iterator combinators.
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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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#[clippy::version = "1.30.0"]
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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<'tcx> LateLintPass<'tcx> for CopyIterator {
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fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
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if_chain! {
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if let ItemKind::Impl(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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let ty = cx.tcx.type_of(item.owner_id);
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if is_copy(cx, ty);
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if let Some(trait_id) = trait_ref.trait_def_id();
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if cx.tcx.is_diagnostic_item(sym::Iterator, trait_id);
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then {
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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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