2 use rustc::{declare_lint, lint_array};
3 use if_chain::if_chain;
5 use crate::utils::{is_automatically_derived, span_lint};
7 /// **What it does:** Checks for manual re-implementations of `PartialEq::ne`.
9 /// **Why is this bad?** `PartialEq::ne` is required to always return the
10 /// negated result of `PartialEq::eq`, which is exactly what the default
11 /// implementation does. Therefore, there should never be any need to
14 /// **Known problems:** None.
20 /// impl PartialEq for Foo {
21 /// fn eq(&self, other: &Foo) -> bool { ... }
22 /// fn ne(&self, other: &Foo) -> bool { !(self == other) }
25 declare_clippy_lint! {
26 pub PARTIALEQ_NE_IMPL,
28 "re-implementing `PartialEq::ne`"
31 #[derive(Clone, Copy)]
34 impl LintPass for Pass {
35 fn get_lints(&self) -> LintArray {
36 lint_array!(PARTIALEQ_NE_IMPL)
40 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
41 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
43 if let ItemKind::Impl(_, _, _, _, Some(ref trait_ref), _, ref impl_items) = item.node;
44 if !is_automatically_derived(&*item.attrs);
45 if let Some(eq_trait) = cx.tcx.lang_items().eq_trait();
46 if trait_ref.path.def.def_id() == eq_trait;
48 for impl_item in impl_items {
49 if impl_item.ident.name == "ne" {
53 "re-implementing `PartialEq::ne` is unnecessary")