1 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note, span_lint_and_then};
2 use clippy_utils::paths;
3 use clippy_utils::ty::{implements_trait, is_copy};
4 use clippy_utils::{get_trait_def_id, is_automatically_derived, is_lint_allowed, match_def_path};
5 use if_chain::if_chain;
6 use rustc_hir::intravisit::{walk_expr, walk_fn, walk_item, FnKind, NestedVisitorMap, Visitor};
8 BlockCheckMode, BodyId, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, TraitRef, UnsafeSource, Unsafety,
10 use rustc_lint::{LateContext, LateLintPass};
11 use rustc_middle::hir::map::Map;
12 use rustc_middle::ty::{self, Ty};
13 use rustc_session::{declare_lint_pass, declare_tool_lint};
14 use rustc_span::source_map::Span;
16 declare_clippy_lint! {
18 /// Checks for deriving `Hash` but implementing `PartialEq`
19 /// explicitly or vice versa.
21 /// ### Why is this bad?
22 /// 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)
36 /// impl PartialEq for Foo {
40 #[clippy::version = "pre 1.29.0"]
41 pub DERIVE_HASH_XOR_EQ,
43 "deriving `Hash` but implementing `PartialEq` explicitly"
46 declare_clippy_lint! {
48 /// Checks for deriving `Ord` but implementing `PartialOrd`
49 /// explicitly or vice versa.
51 /// ### Why is this bad?
52 /// The implementation of these traits must agree (for
53 /// example for use with `sort`) so it’s probably a bad idea to use a
54 /// default-generated `Ord` implementation with an explicitly defined
55 /// `PartialOrd`. In particular, the following must hold for any type
56 /// implementing `Ord`:
59 /// k1.cmp(&k2) == k1.partial_cmp(&k2).unwrap()
64 /// #[derive(Ord, PartialEq, Eq)]
67 /// impl PartialOrd for Foo {
73 /// #[derive(PartialEq, Eq)]
76 /// impl PartialOrd for Foo {
77 /// fn partial_cmp(&self, other: &Foo) -> Option<Ordering> {
78 /// Some(self.cmp(other))
82 /// impl Ord for Foo {
86 /// or, if you don't need a custom ordering:
88 /// #[derive(Ord, PartialOrd, PartialEq, Eq)]
91 #[clippy::version = "1.47.0"]
92 pub DERIVE_ORD_XOR_PARTIAL_ORD,
94 "deriving `Ord` but implementing `PartialOrd` explicitly"
97 declare_clippy_lint! {
99 /// Checks for explicit `Clone` implementations for `Copy`
102 /// ### Why is this bad?
103 /// To avoid surprising behaviour, these traits should
104 /// agree and the behaviour of `Copy` cannot be overridden. In almost all
105 /// situations a `Copy` type should have a `Clone` implementation that does
106 /// nothing more than copy the object, which is what `#[derive(Copy, Clone)]`
114 /// impl Clone for Foo {
118 #[clippy::version = "pre 1.29.0"]
119 pub EXPL_IMPL_CLONE_ON_COPY,
121 "implementing `Clone` explicitly on `Copy` types"
124 declare_clippy_lint! {
126 /// Checks for deriving `serde::Deserialize` on a type that
127 /// has methods using `unsafe`.
129 /// ### Why is this bad?
130 /// Deriving `serde::Deserialize` will create a constructor
131 /// that may violate invariants hold by another constructor.
135 /// use serde::Deserialize;
137 /// #[derive(Deserialize)]
143 /// pub fn new() -> Self {
147 /// pub unsafe fn parts() -> (&str, &str) {
148 /// // assumes invariants hold
152 #[clippy::version = "1.45.0"]
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 attrs = cx.tcx.hir().attrs(item.hir_id());
174 let is_automatically_derived = is_automatically_derived(attrs);
176 check_hash_peq(cx, item.span, trait_ref, ty, is_automatically_derived);
177 check_ord_partial_ord(cx, item.span, trait_ref, ty, is_automatically_derived);
179 if is_automatically_derived {
180 check_unsafe_derive_deserialize(cx, item, trait_ref, ty);
182 check_copy_clone(cx, item, trait_ref, ty);
188 /// Implementation of the `DERIVE_HASH_XOR_EQ` lint.
189 fn check_hash_peq<'tcx>(
190 cx: &LateContext<'tcx>,
192 trait_ref: &TraitRef<'_>,
194 hash_is_automatically_derived: bool,
197 if let Some(peq_trait_def_id) = cx.tcx.lang_items().eq_trait();
198 if let Some(def_id) = trait_ref.trait_def_id();
199 if match_def_path(cx, def_id, &paths::HASH);
201 // Look for the PartialEq implementations for `ty`
202 cx.tcx.for_each_relevant_impl(peq_trait_def_id, ty, |impl_id| {
203 let peq_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
205 if peq_is_automatically_derived == hash_is_automatically_derived {
209 let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
211 // Only care about `impl PartialEq<Foo> for Foo`
212 // For `impl PartialEq<B> for A, input_types is [A, B]
213 if trait_ref.substs.type_at(1) == ty {
214 let mess = if peq_is_automatically_derived {
215 "you are implementing `Hash` explicitly but have derived `PartialEq`"
217 "you are deriving `Hash` but have implemented `PartialEq` explicitly"
226 if let Some(local_def_id) = impl_id.as_local() {
227 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
229 cx.tcx.hir().span(hir_id),
230 "`PartialEq` implemented here"
241 /// Implementation of the `DERIVE_ORD_XOR_PARTIAL_ORD` lint.
242 fn check_ord_partial_ord<'tcx>(
243 cx: &LateContext<'tcx>,
245 trait_ref: &TraitRef<'_>,
247 ord_is_automatically_derived: bool,
250 if let Some(ord_trait_def_id) = get_trait_def_id(cx, &paths::ORD);
251 if let Some(partial_ord_trait_def_id) = cx.tcx.lang_items().partial_ord_trait();
252 if let Some(def_id) = &trait_ref.trait_def_id();
253 if *def_id == ord_trait_def_id;
255 // Look for the PartialOrd implementations for `ty`
256 cx.tcx.for_each_relevant_impl(partial_ord_trait_def_id, ty, |impl_id| {
257 let partial_ord_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
259 if partial_ord_is_automatically_derived == ord_is_automatically_derived {
263 let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
265 // Only care about `impl PartialOrd<Foo> for Foo`
266 // For `impl PartialOrd<B> for A, input_types is [A, B]
267 if trait_ref.substs.type_at(1) == ty {
268 let mess = if partial_ord_is_automatically_derived {
269 "you are implementing `Ord` explicitly but have derived `PartialOrd`"
271 "you are deriving `Ord` but have implemented `PartialOrd` explicitly"
276 DERIVE_ORD_XOR_PARTIAL_ORD,
280 if let Some(local_def_id) = impl_id.as_local() {
281 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
283 cx.tcx.hir().span(hir_id),
284 "`PartialOrd` implemented here"
295 /// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint.
296 fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &TraitRef<'_>, ty: Ty<'tcx>) {
297 let clone_id = match cx.tcx.lang_items().clone_trait() {
298 Some(id) if trait_ref.trait_def_id() == Some(id) => id,
301 let copy_id = match cx.tcx.lang_items().copy_trait() {
305 let (ty_adt, ty_subs) = match *ty.kind() {
306 // Unions can't derive clone.
307 ty::Adt(adt, subs) if !adt.is_union() => (adt, subs),
310 // If the current self type doesn't implement Copy (due to generic constraints), search to see if
311 // there's a Copy impl for any instance of the adt.
312 if !is_copy(cx, ty) {
313 if ty_subs.non_erasable_generics().next().is_some() {
314 let has_copy_impl = cx.tcx.all_local_trait_impls(()).get(©_id).map_or(false, |impls| {
317 .any(|&id| matches!(cx.tcx.type_of(id).kind(), ty::Adt(adt, _) if ty_adt.did == adt.did))
326 // Derive constrains all generic types to requiring Clone. Check if any type is not constrained for
328 if ty_subs.types().any(|ty| !implements_trait(cx, ty, clone_id, &[])) {
334 EXPL_IMPL_CLONE_ON_COPY,
336 "you are implementing `Clone` explicitly on a `Copy` type",
338 "consider deriving `Clone` or removing `Copy`",
342 /// Implementation of the `UNSAFE_DERIVE_DESERIALIZE` lint.
343 fn check_unsafe_derive_deserialize<'tcx>(
344 cx: &LateContext<'tcx>,
346 trait_ref: &TraitRef<'_>,
349 fn has_unsafe<'tcx>(cx: &LateContext<'tcx>, item: &'tcx Item<'_>) -> bool {
350 let mut visitor = UnsafeVisitor { cx, has_unsafe: false };
351 walk_item(&mut visitor, item);
356 if let Some(trait_def_id) = trait_ref.trait_def_id();
357 if match_def_path(cx, trait_def_id, &paths::SERDE_DESERIALIZE);
358 if let ty::Adt(def, _) = ty.kind();
359 if let Some(local_def_id) = def.did.as_local();
360 let adt_hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
361 if !is_lint_allowed(cx, UNSAFE_DERIVE_DESERIALIZE, adt_hir_id);
362 if cx.tcx.inherent_impls(def.did)
364 .map(|imp_did| cx.tcx.hir().expect_item(imp_did.expect_local()))
365 .any(|imp| has_unsafe(cx, imp));
369 UNSAFE_DERIVE_DESERIALIZE,
371 "you are deriving `serde::Deserialize` on a type that has methods using `unsafe`",
373 "consider implementing `serde::Deserialize` manually. See https://serde.rs/impl-deserialize.html"
379 struct UnsafeVisitor<'a, 'tcx> {
380 cx: &'a LateContext<'tcx>,
384 impl<'tcx> Visitor<'tcx> for UnsafeVisitor<'_, 'tcx> {
385 type Map = Map<'tcx>;
387 fn visit_fn(&mut self, kind: FnKind<'tcx>, decl: &'tcx FnDecl<'_>, body_id: BodyId, span: Span, id: HirId) {
393 if let Some(header) = kind.header();
394 if header.unsafety == Unsafety::Unsafe;
396 self.has_unsafe = true;
400 walk_fn(self, kind, decl, body_id, span, id);
403 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
408 if let ExprKind::Block(block, _) = expr.kind {
409 if block.rules == BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) {
410 self.has_unsafe = true;
414 walk_expr(self, expr);
417 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
418 NestedVisitorMap::All(self.cx.tcx.hir())