59 lines
1.7 KiB
Rust
59 lines
1.7 KiB
Rust
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;
|
|
use rustc_span::sym;
|
|
|
|
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 let ItemKind::Impl(Impl {
|
|
of_trait: Some(ref trait_ref),
|
|
..
|
|
}) = item.kind
|
|
&& let ty = cx.tcx.type_of(item.owner_id).instantiate_identity()
|
|
&& is_copy(cx, ty)
|
|
&& let Some(trait_id) = trait_ref.trait_def_id()
|
|
&& cx.tcx.is_diagnostic_item(sym::Iterator, trait_id)
|
|
{
|
|
span_lint_and_note(
|
|
cx,
|
|
COPY_ITERATOR,
|
|
item.span,
|
|
"you are implementing `Iterator` on a `Copy` type",
|
|
None,
|
|
"consider implementing `IntoIterator` instead",
|
|
);
|
|
}
|
|
}
|
|
}
|