mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-13 14:52:46 +00:00
66 lines
2.1 KiB
Rust
66 lines
2.1 KiB
Rust
// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use crate::rustc::hir::{Item, ItemKind};
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use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
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use crate::rustc::{declare_tool_lint, lint_array};
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use crate::utils::{is_copy, match_path, paths, span_note_and_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
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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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declare_clippy_lint! {
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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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pub struct CopyIterator;
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impl LintPass for CopyIterator {
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fn get_lints(&self) -> LintArray {
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lint_array![COPY_ITERATOR]
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}
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}
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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(_, _, _, _, Some(ref trait_ref), _, _) = item.node {
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let ty = cx.tcx.type_of(cx.tcx.hir().local_def_id(item.id));
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if is_copy(cx, ty) && match_path(&trait_ref.path, &paths::ITERATOR) {
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span_note_and_lint(
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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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item.span,
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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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