1 use crate::utils::paths;
3 get_trait_def_id, is_allowed, is_automatically_derived, is_copy, match_def_path, match_path, span_lint_and_help,
4 span_lint_and_note, span_lint_and_then,
6 use if_chain::if_chain;
7 use rustc_hir::def_id::DefId;
8 use rustc_hir::intravisit::{walk_expr, walk_fn, walk_item, FnKind, NestedVisitorMap, Visitor};
10 BlockCheckMode, BodyId, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, TraitRef, UnsafeSource, Unsafety,
12 use rustc_lint::{LateContext, LateLintPass};
13 use rustc_middle::hir::map::Map;
14 use rustc_middle::ty::{self, Ty};
15 use rustc_session::{declare_lint_pass, declare_tool_lint};
16 use rustc_span::source_map::Span;
18 declare_clippy_lint! {
19 /// **What it does:** Checks for deriving `Hash` but implementing `PartialEq`
20 /// explicitly or vice versa.
22 /// **Why is this bad?** The implementation of these traits must agree (for
23 /// example for use with `HashMap`) so it’s probably a bad idea to use a
24 /// default-generated `Hash` implementation with an explicitly defined
25 /// `PartialEq`. In particular, the following must hold for any type:
28 /// k1 == k2 ⇒ hash(k1) == hash(k2)
31 /// **Known problems:** None.
38 /// impl PartialEq for Foo {
42 pub DERIVE_HASH_XOR_EQ,
44 "deriving `Hash` but implementing `PartialEq` explicitly"
47 declare_clippy_lint! {
48 /// **What it does:** Checks for deriving `Ord` but implementing `PartialOrd`
49 /// explicitly or vice versa.
51 /// **Why is this bad?** The implementation of these traits must agree (for
52 /// example for use with `sort`) so it’s probably a bad idea to use a
53 /// default-generated `Ord` implementation with an explicitly defined
54 /// `PartialOrd`. In particular, the following must hold for any type
55 /// implementing `Ord`:
58 /// k1.cmp(&k2) == k1.partial_cmp(&k2).unwrap()
61 /// **Known problems:** None.
66 /// #[derive(Ord, PartialEq, Eq)]
69 /// impl PartialOrd for Foo {
75 /// #[derive(PartialEq, Eq)]
78 /// impl PartialOrd for Foo {
79 /// fn partial_cmp(&self, other: &Foo) -> Option<Ordering> {
80 /// Some(self.cmp(other))
84 /// impl Ord for Foo {
88 /// or, if you don't need a custom ordering:
90 /// #[derive(Ord, PartialOrd, PartialEq, Eq)]
93 pub DERIVE_ORD_XOR_PARTIAL_ORD,
95 "deriving `Ord` but implementing `PartialOrd` explicitly"
98 declare_clippy_lint! {
99 /// **What it does:** Checks for explicit `Clone` implementations for `Copy`
102 /// **Why is this bad?** To avoid surprising behaviour, these traits should
103 /// agree and the behaviour of `Copy` cannot be overridden. In almost all
104 /// situations a `Copy` type should have a `Clone` implementation that does
105 /// nothing more than copy the object, which is what `#[derive(Copy, Clone)]`
108 /// **Known problems:** Bounds of generic types are sometimes wrong: https://github.com/rust-lang/rust/issues/26925
115 /// impl Clone for Foo {
119 pub EXPL_IMPL_CLONE_ON_COPY,
121 "implementing `Clone` explicitly on `Copy` types"
124 declare_clippy_lint! {
125 /// **What it does:** Checks for deriving `serde::Deserialize` on a type that
126 /// has methods using `unsafe`.
128 /// **Why is this bad?** Deriving `serde::Deserialize` will create a constructor
129 /// that may violate invariants hold by another constructor.
131 /// **Known problems:** None.
136 /// use serde::Deserialize;
138 /// #[derive(Deserialize)]
144 /// pub fn new() -> Self {
148 /// pub unsafe fn parts() -> (&str, &str) {
149 /// // assumes invariants hold
153 pub UNSAFE_DERIVE_DESERIALIZE,
155 "deriving `serde::Deserialize` on a type that has methods using `unsafe`"
158 declare_lint_pass!(Derive => [
159 EXPL_IMPL_CLONE_ON_COPY,
161 DERIVE_ORD_XOR_PARTIAL_ORD,
162 UNSAFE_DERIVE_DESERIALIZE
165 impl<'tcx> LateLintPass<'tcx> for Derive {
166 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
167 if let ItemKind::Impl(Impl {
168 of_trait: Some(ref trait_ref),
172 let ty = cx.tcx.type_of(item.def_id);
173 let is_automatically_derived = is_automatically_derived(&*item.attrs);
175 check_hash_peq(cx, item.span, trait_ref, ty, is_automatically_derived);
176 check_ord_partial_ord(cx, item.span, trait_ref, ty, is_automatically_derived);
178 if is_automatically_derived {
179 check_unsafe_derive_deserialize(cx, item, trait_ref, ty);
181 check_copy_clone(cx, item, trait_ref, ty);
187 /// Implementation of the `DERIVE_HASH_XOR_EQ` lint.
188 fn check_hash_peq<'tcx>(
189 cx: &LateContext<'tcx>,
191 trait_ref: &TraitRef<'_>,
193 hash_is_automatically_derived: bool,
196 if let Some(peq_trait_def_id) = cx.tcx.lang_items().eq_trait();
197 if let Some(def_id) = trait_ref.trait_def_id();
198 if match_def_path(cx, def_id, &paths::HASH);
200 // Look for the PartialEq implementations for `ty`
201 cx.tcx.for_each_relevant_impl(peq_trait_def_id, ty, |impl_id| {
202 let peq_is_automatically_derived = is_automatically_derived(&cx.tcx.get_attrs(impl_id));
204 if peq_is_automatically_derived == hash_is_automatically_derived {
208 let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
210 // Only care about `impl PartialEq<Foo> for Foo`
211 // For `impl PartialEq<B> for A, input_types is [A, B]
212 if trait_ref.substs.type_at(1) == ty {
213 let mess = if peq_is_automatically_derived {
214 "you are implementing `Hash` explicitly but have derived `PartialEq`"
216 "you are deriving `Hash` but have implemented `PartialEq` explicitly"
225 if let Some(local_def_id) = impl_id.as_local() {
226 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
228 cx.tcx.hir().span(hir_id),
229 "`PartialEq` implemented here"
240 /// Implementation of the `DERIVE_ORD_XOR_PARTIAL_ORD` lint.
241 fn check_ord_partial_ord<'tcx>(
242 cx: &LateContext<'tcx>,
244 trait_ref: &TraitRef<'_>,
246 ord_is_automatically_derived: bool,
249 if let Some(ord_trait_def_id) = get_trait_def_id(cx, &paths::ORD);
250 if let Some(partial_ord_trait_def_id) = cx.tcx.lang_items().partial_ord_trait();
251 if let Some(def_id) = &trait_ref.trait_def_id();
252 if *def_id == ord_trait_def_id;
254 // Look for the PartialOrd implementations for `ty`
255 cx.tcx.for_each_relevant_impl(partial_ord_trait_def_id, ty, |impl_id| {
256 let partial_ord_is_automatically_derived = is_automatically_derived(&cx.tcx.get_attrs(impl_id));
258 if partial_ord_is_automatically_derived == ord_is_automatically_derived {
262 let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
264 // Only care about `impl PartialOrd<Foo> for Foo`
265 // For `impl PartialOrd<B> for A, input_types is [A, B]
266 if trait_ref.substs.type_at(1) == ty {
267 let mess = if partial_ord_is_automatically_derived {
268 "you are implementing `Ord` explicitly but have derived `PartialOrd`"
270 "you are deriving `Ord` but have implemented `PartialOrd` explicitly"
275 DERIVE_ORD_XOR_PARTIAL_ORD,
279 if let Some(local_def_id) = impl_id.as_local() {
280 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
282 cx.tcx.hir().span(hir_id),
283 "`PartialOrd` implemented here"
294 /// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint.
295 fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &TraitRef<'_>, ty: Ty<'tcx>) {
296 if match_path(&trait_ref.path, &paths::CLONE_TRAIT) {
297 if !is_copy(cx, ty) {
302 ty::Adt(def, _) if def.is_union() => return,
304 // Some types are not Clone by default but could be cloned “by hand” if necessary
305 ty::Adt(def, substs) => {
306 for variant in &def.variants {
307 for field in &variant.fields {
308 if let ty::FnDef(..) = field.ty(cx.tcx, substs).kind() {
312 for subst in substs {
313 if let ty::subst::GenericArgKind::Type(subst) = subst.unpack() {
314 if let ty::Param(_) = subst.kind() {
326 EXPL_IMPL_CLONE_ON_COPY,
328 "you are implementing `Clone` explicitly on a `Copy` type",
330 "consider deriving `Clone` or removing `Copy`",
335 /// Implementation of the `UNSAFE_DERIVE_DESERIALIZE` lint.
336 fn check_unsafe_derive_deserialize<'tcx>(
337 cx: &LateContext<'tcx>,
339 trait_ref: &TraitRef<'_>,
342 fn item_from_def_id<'tcx>(cx: &LateContext<'tcx>, def_id: DefId) -> &'tcx Item<'tcx> {
343 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
344 cx.tcx.hir().expect_item(hir_id)
347 fn has_unsafe<'tcx>(cx: &LateContext<'tcx>, item: &'tcx Item<'_>) -> bool {
348 let mut visitor = UnsafeVisitor { cx, has_unsafe: false };
349 walk_item(&mut visitor, item);
354 if let Some(trait_def_id) = trait_ref.trait_def_id();
355 if match_def_path(cx, trait_def_id, &paths::SERDE_DESERIALIZE);
356 if let ty::Adt(def, _) = ty.kind();
357 if let Some(local_def_id) = def.did.as_local();
358 let adt_hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
359 if !is_allowed(cx, UNSAFE_DERIVE_DESERIALIZE, adt_hir_id);
360 if cx.tcx.inherent_impls(def.did)
362 .map(|imp_did| item_from_def_id(cx, *imp_did))
363 .any(|imp| has_unsafe(cx, imp));
367 UNSAFE_DERIVE_DESERIALIZE,
369 "you are deriving `serde::Deserialize` on a type that has methods using `unsafe`",
371 "consider implementing `serde::Deserialize` manually. See https://serde.rs/impl-deserialize.html"
377 struct UnsafeVisitor<'a, 'tcx> {
378 cx: &'a LateContext<'tcx>,
382 impl<'tcx> Visitor<'tcx> for UnsafeVisitor<'_, 'tcx> {
383 type Map = Map<'tcx>;
385 fn visit_fn(&mut self, kind: FnKind<'tcx>, decl: &'tcx FnDecl<'_>, body_id: BodyId, span: Span, id: HirId) {
391 if let Some(header) = kind.header();
392 if let Unsafety::Unsafe = header.unsafety;
394 self.has_unsafe = true;
398 walk_fn(self, kind, decl, body_id, span, id);
401 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
406 if let ExprKind::Block(block, _) = expr.kind {
408 BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided)
409 | BlockCheckMode::PushUnsafeBlock(UnsafeSource::UserProvided)
410 | BlockCheckMode::PopUnsafeBlock(UnsafeSource::UserProvided) => {
411 self.has_unsafe = true;
417 walk_expr(self, expr);
420 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
421 NestedVisitorMap::All(self.cx.tcx.hir())