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::{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, 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::nested_filter;
12 use rustc_middle::ty::{self, Ty};
13 use rustc_session::{declare_lint_pass, declare_tool_lint};
14 use rustc_span::source_map::Span;
17 declare_clippy_lint! {
19 /// Checks for deriving `Hash` but implementing `PartialEq`
20 /// explicitly or vice versa.
22 /// ### Why is this bad?
23 /// The implementation of these traits must agree (for
24 /// example for use with `HashMap`) so it’s probably a bad idea to use a
25 /// default-generated `Hash` implementation with an explicitly defined
26 /// `PartialEq`. In particular, the following must hold for any type:
29 /// k1 == k2 ⇒ hash(k1) == hash(k2)
37 /// impl PartialEq for Foo {
41 #[clippy::version = "pre 1.29.0"]
42 pub DERIVE_HASH_XOR_EQ,
44 "deriving `Hash` but implementing `PartialEq` explicitly"
47 declare_clippy_lint! {
49 /// Checks for deriving `Ord` but implementing `PartialOrd`
50 /// explicitly or vice versa.
52 /// ### Why is this bad?
53 /// The implementation of these traits must agree (for
54 /// example for use with `sort`) so it’s probably a bad idea to use a
55 /// default-generated `Ord` implementation with an explicitly defined
56 /// `PartialOrd`. In particular, the following must hold for any type
57 /// implementing `Ord`:
60 /// k1.cmp(&k2) == k1.partial_cmp(&k2).unwrap()
65 /// #[derive(Ord, PartialEq, Eq)]
68 /// impl PartialOrd for Foo {
74 /// #[derive(PartialEq, Eq)]
77 /// impl PartialOrd for Foo {
78 /// fn partial_cmp(&self, other: &Foo) -> Option<Ordering> {
79 /// Some(self.cmp(other))
83 /// impl Ord for Foo {
87 /// or, if you don't need a custom ordering:
89 /// #[derive(Ord, PartialOrd, PartialEq, Eq)]
92 #[clippy::version = "1.47.0"]
93 pub DERIVE_ORD_XOR_PARTIAL_ORD,
95 "deriving `Ord` but implementing `PartialOrd` explicitly"
98 declare_clippy_lint! {
100 /// Checks for explicit `Clone` implementations for `Copy`
103 /// ### Why is this bad?
104 /// To avoid surprising behaviour, these traits should
105 /// agree and the behaviour of `Copy` cannot be overridden. In almost all
106 /// situations a `Copy` type should have a `Clone` implementation that does
107 /// nothing more than copy the object, which is what `#[derive(Copy, Clone)]`
115 /// impl Clone for Foo {
119 #[clippy::version = "pre 1.29.0"]
120 pub EXPL_IMPL_CLONE_ON_COPY,
122 "implementing `Clone` explicitly on `Copy` types"
125 declare_clippy_lint! {
127 /// Checks for deriving `serde::Deserialize` on a type that
128 /// has methods using `unsafe`.
130 /// ### Why is this bad?
131 /// Deriving `serde::Deserialize` will create a constructor
132 /// that may violate invariants hold by another constructor.
136 /// use serde::Deserialize;
138 /// #[derive(Deserialize)]
144 /// pub fn new() -> Self {
148 /// pub unsafe fn parts() -> (&str, &str) {
149 /// // assumes invariants hold
153 #[clippy::version = "1.45.0"]
154 pub UNSAFE_DERIVE_DESERIALIZE,
156 "deriving `serde::Deserialize` on a type that has methods using `unsafe`"
159 declare_lint_pass!(Derive => [
160 EXPL_IMPL_CLONE_ON_COPY,
162 DERIVE_ORD_XOR_PARTIAL_ORD,
163 UNSAFE_DERIVE_DESERIALIZE
166 impl<'tcx> LateLintPass<'tcx> for Derive {
167 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
168 if let ItemKind::Impl(Impl {
169 of_trait: Some(ref trait_ref),
173 let ty = cx.tcx.type_of(item.def_id);
174 let attrs = cx.tcx.hir().attrs(item.hir_id());
175 let is_automatically_derived = is_automatically_derived(attrs);
177 check_hash_peq(cx, item.span, trait_ref, ty, is_automatically_derived);
178 check_ord_partial_ord(cx, item.span, trait_ref, ty, is_automatically_derived);
180 if is_automatically_derived {
181 check_unsafe_derive_deserialize(cx, item, trait_ref, ty);
183 check_copy_clone(cx, item, trait_ref, ty);
189 /// Implementation of the `DERIVE_HASH_XOR_EQ` lint.
190 fn check_hash_peq<'tcx>(
191 cx: &LateContext<'tcx>,
193 trait_ref: &TraitRef<'_>,
195 hash_is_automatically_derived: bool,
198 if let Some(peq_trait_def_id) = cx.tcx.lang_items().eq_trait();
199 if let Some(def_id) = trait_ref.trait_def_id();
200 if cx.tcx.is_diagnostic_item(sym::Hash, def_id);
202 // Look for the PartialEq implementations for `ty`
203 cx.tcx.for_each_relevant_impl(peq_trait_def_id, ty, |impl_id| {
204 let peq_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
206 if peq_is_automatically_derived == hash_is_automatically_derived {
210 let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
212 // Only care about `impl PartialEq<Foo> for Foo`
213 // For `impl PartialEq<B> for A, input_types is [A, B]
214 if trait_ref.substs.type_at(1) == ty {
215 let mess = if peq_is_automatically_derived {
216 "you are implementing `Hash` explicitly but have derived `PartialEq`"
218 "you are deriving `Hash` but have implemented `PartialEq` explicitly"
227 if let Some(local_def_id) = impl_id.as_local() {
228 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
230 cx.tcx.hir().span(hir_id),
231 "`PartialEq` implemented here"
242 /// Implementation of the `DERIVE_ORD_XOR_PARTIAL_ORD` lint.
243 fn check_ord_partial_ord<'tcx>(
244 cx: &LateContext<'tcx>,
246 trait_ref: &TraitRef<'_>,
248 ord_is_automatically_derived: bool,
251 if let Some(ord_trait_def_id) = cx.tcx.get_diagnostic_item(sym::Ord);
252 if let Some(partial_ord_trait_def_id) = cx.tcx.lang_items().partial_ord_trait();
253 if let Some(def_id) = &trait_ref.trait_def_id();
254 if *def_id == ord_trait_def_id;
256 // Look for the PartialOrd implementations for `ty`
257 cx.tcx.for_each_relevant_impl(partial_ord_trait_def_id, ty, |impl_id| {
258 let partial_ord_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
260 if partial_ord_is_automatically_derived == ord_is_automatically_derived {
264 let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
266 // Only care about `impl PartialOrd<Foo> for Foo`
267 // For `impl PartialOrd<B> for A, input_types is [A, B]
268 if trait_ref.substs.type_at(1) == ty {
269 let mess = if partial_ord_is_automatically_derived {
270 "you are implementing `Ord` explicitly but have derived `PartialOrd`"
272 "you are deriving `Ord` but have implemented `PartialOrd` explicitly"
277 DERIVE_ORD_XOR_PARTIAL_ORD,
281 if let Some(local_def_id) = impl_id.as_local() {
282 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
284 cx.tcx.hir().span(hir_id),
285 "`PartialOrd` implemented here"
296 /// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint.
297 fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &TraitRef<'_>, ty: Ty<'tcx>) {
298 let clone_id = match cx.tcx.lang_items().clone_trait() {
299 Some(id) if trait_ref.trait_def_id() == Some(id) => id,
302 let copy_id = match cx.tcx.lang_items().copy_trait() {
306 let (ty_adt, ty_subs) = match *ty.kind() {
307 // Unions can't derive clone.
308 ty::Adt(adt, subs) if !adt.is_union() => (adt, subs),
311 // If the current self type doesn't implement Copy (due to generic constraints), search to see if
312 // there's a Copy impl for any instance of the adt.
313 if !is_copy(cx, ty) {
314 if ty_subs.non_erasable_generics().next().is_some() {
315 let has_copy_impl = cx.tcx.all_local_trait_impls(()).get(©_id).map_or(false, |impls| {
318 .any(|&id| matches!(cx.tcx.type_of(id).kind(), ty::Adt(adt, _) if ty_adt.did() == adt.did()))
327 // Derive constrains all generic types to requiring Clone. Check if any type is not constrained for
329 if ty_subs.types().any(|ty| !implements_trait(cx, ty, clone_id, &[])) {
335 EXPL_IMPL_CLONE_ON_COPY,
337 "you are implementing `Clone` explicitly on a `Copy` type",
339 "consider deriving `Clone` or removing `Copy`",
343 /// Implementation of the `UNSAFE_DERIVE_DESERIALIZE` lint.
344 fn check_unsafe_derive_deserialize<'tcx>(
345 cx: &LateContext<'tcx>,
347 trait_ref: &TraitRef<'_>,
350 fn has_unsafe<'tcx>(cx: &LateContext<'tcx>, item: &'tcx Item<'_>) -> bool {
351 let mut visitor = UnsafeVisitor { cx, has_unsafe: false };
352 walk_item(&mut visitor, item);
357 if let Some(trait_def_id) = trait_ref.trait_def_id();
358 if match_def_path(cx, trait_def_id, &paths::SERDE_DESERIALIZE);
359 if let ty::Adt(def, _) = ty.kind();
360 if let Some(local_def_id) = def.did().as_local();
361 let adt_hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
362 if !is_lint_allowed(cx, UNSAFE_DERIVE_DESERIALIZE, adt_hir_id);
363 if cx.tcx.inherent_impls(def.did())
365 .map(|imp_did| cx.tcx.hir().expect_item(imp_did.expect_local()))
366 .any(|imp| has_unsafe(cx, imp));
370 UNSAFE_DERIVE_DESERIALIZE,
372 "you are deriving `serde::Deserialize` on a type that has methods using `unsafe`",
374 "consider implementing `serde::Deserialize` manually. See https://serde.rs/impl-deserialize.html"
380 struct UnsafeVisitor<'a, 'tcx> {
381 cx: &'a LateContext<'tcx>,
385 impl<'tcx> Visitor<'tcx> for UnsafeVisitor<'_, 'tcx> {
386 type NestedFilter = nested_filter::All;
388 fn visit_fn(&mut self, kind: FnKind<'tcx>, decl: &'tcx FnDecl<'_>, body_id: BodyId, span: Span, id: HirId) {
394 if let Some(header) = kind.header();
395 if header.unsafety == Unsafety::Unsafe;
397 self.has_unsafe = true;
401 walk_fn(self, kind, decl, body_id, span, id);
404 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
409 if let ExprKind::Block(block, _) = expr.kind {
410 if block.rules == BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) {
411 self.has_unsafe = true;
415 walk_expr(self, expr);
418 fn nested_visit_map(&mut self) -> Self::Map {