1 use clippy_utils::diagnostics::span_lint_hir;
2 use clippy_utils::is_automatically_derived;
3 use if_chain::if_chain;
4 use rustc_hir::{Impl, Item, ItemKind};
5 use rustc_lint::{LateContext, LateLintPass};
6 use rustc_session::{declare_lint_pass, declare_tool_lint};
11 /// Checks for manual re-implementations of `PartialEq::ne`.
13 /// ### Why is this bad?
14 /// `PartialEq::ne` is required to always return the
15 /// negated result of `PartialEq::eq`, which is exactly what the default
16 /// implementation does. Therefore, there should never be any need to
23 /// impl PartialEq for Foo {
24 /// fn eq(&self, other: &Foo) -> bool { true }
25 /// fn ne(&self, other: &Foo) -> bool { !(self == other) }
28 #[clippy::version = "pre 1.29.0"]
29 pub PARTIALEQ_NE_IMPL,
31 "re-implementing `PartialEq::ne`"
34 declare_lint_pass!(PartialEqNeImpl => [PARTIALEQ_NE_IMPL]);
36 impl<'tcx> LateLintPass<'tcx> for PartialEqNeImpl {
37 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
39 if let ItemKind::Impl(Impl { of_trait: Some(ref trait_ref), items: impl_items, .. }) = item.kind;
40 let attrs = cx.tcx.hir().attrs(item.hir_id());
41 if !is_automatically_derived(attrs);
42 if let Some(eq_trait) = cx.tcx.lang_items().eq_trait();
43 if trait_ref.path.res.def_id() == eq_trait;
45 for impl_item in impl_items {
46 if impl_item.ident.name == sym::ne {
50 impl_item.id.hir_id(),
52 "re-implementing `PartialEq::ne` is unnecessary",