1 use crate::utils::paths;
3 get_trait_def_id, is_allowed, is_automatically_derived, match_def_path, span_lint_and_help, span_lint_and_note,
6 use clippy_utils::ty::is_copy;
7 use if_chain::if_chain;
8 use rustc_hir::def_id::DefId;
9 use rustc_hir::intravisit::{walk_expr, walk_fn, walk_item, FnKind, NestedVisitorMap, Visitor};
11 BlockCheckMode, BodyId, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, TraitRef, UnsafeSource, Unsafety,
13 use rustc_lint::{LateContext, LateLintPass};
14 use rustc_middle::hir::map::Map;
15 use rustc_middle::ty::{self, Ty};
16 use rustc_session::{declare_lint_pass, declare_tool_lint};
17 use rustc_span::source_map::Span;
19 declare_clippy_lint! {
20 /// **What it does:** Checks for deriving `Hash` but implementing `PartialEq`
21 /// explicitly or vice versa.
23 /// **Why is this bad?** 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)
32 /// **Known problems:** None.
39 /// impl PartialEq for Foo {
43 pub DERIVE_HASH_XOR_EQ,
45 "deriving `Hash` but implementing `PartialEq` explicitly"
48 declare_clippy_lint! {
49 /// **What it does:** Checks for deriving `Ord` but implementing `PartialOrd`
50 /// explicitly or vice versa.
52 /// **Why is this bad?** 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()
62 /// **Known problems:** None.
67 /// #[derive(Ord, PartialEq, Eq)]
70 /// impl PartialOrd for Foo {
76 /// #[derive(PartialEq, Eq)]
79 /// impl PartialOrd for Foo {
80 /// fn partial_cmp(&self, other: &Foo) -> Option<Ordering> {
81 /// Some(self.cmp(other))
85 /// impl Ord for Foo {
89 /// or, if you don't need a custom ordering:
91 /// #[derive(Ord, PartialOrd, PartialEq, Eq)]
94 pub DERIVE_ORD_XOR_PARTIAL_ORD,
96 "deriving `Ord` but implementing `PartialOrd` explicitly"
99 declare_clippy_lint! {
100 /// **What it does:** Checks for explicit `Clone` implementations for `Copy`
103 /// **Why is this bad?** 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)]`
109 /// **Known problems:** Bounds of generic types are sometimes wrong: https://github.com/rust-lang/rust/issues/26925
116 /// impl Clone for Foo {
120 pub EXPL_IMPL_CLONE_ON_COPY,
122 "implementing `Clone` explicitly on `Copy` types"
125 declare_clippy_lint! {
126 /// **What it does:** Checks for deriving `serde::Deserialize` on a type that
127 /// has methods using `unsafe`.
129 /// **Why is this bad?** Deriving `serde::Deserialize` will create a constructor
130 /// that may violate invariants hold by another constructor.
132 /// **Known problems:** None.
137 /// use serde::Deserialize;
139 /// #[derive(Deserialize)]
145 /// pub fn new() -> Self {
149 /// pub unsafe fn parts() -> (&str, &str) {
150 /// // assumes invariants hold
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 match_def_path(cx, def_id, &paths::HASH);
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) = get_trait_def_id(cx, &paths::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>) {
302 .map_or(false, |id| Some(id) == trait_ref.trait_def_id())
304 if !is_copy(cx, ty) {
309 ty::Adt(def, _) if def.is_union() => return,
311 // Some types are not Clone by default but could be cloned “by hand” if necessary
312 ty::Adt(def, substs) => {
313 for variant in &def.variants {
314 for field in &variant.fields {
315 if let ty::FnDef(..) = field.ty(cx.tcx, substs).kind() {
319 for subst in substs {
320 if let ty::subst::GenericArgKind::Type(subst) = subst.unpack() {
321 if let ty::Param(_) = subst.kind() {
333 EXPL_IMPL_CLONE_ON_COPY,
335 "you are implementing `Clone` explicitly on a `Copy` type",
337 "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 item_from_def_id<'tcx>(cx: &LateContext<'tcx>, def_id: DefId) -> &'tcx Item<'tcx> {
350 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
351 cx.tcx.hir().expect_item(hir_id)
354 fn has_unsafe<'tcx>(cx: &LateContext<'tcx>, item: &'tcx Item<'_>) -> bool {
355 let mut visitor = UnsafeVisitor { cx, has_unsafe: false };
356 walk_item(&mut visitor, item);
361 if let Some(trait_def_id) = trait_ref.trait_def_id();
362 if match_def_path(cx, trait_def_id, &paths::SERDE_DESERIALIZE);
363 if let ty::Adt(def, _) = ty.kind();
364 if let Some(local_def_id) = def.did.as_local();
365 let adt_hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
366 if !is_allowed(cx, UNSAFE_DERIVE_DESERIALIZE, adt_hir_id);
367 if cx.tcx.inherent_impls(def.did)
369 .map(|imp_did| item_from_def_id(cx, *imp_did))
370 .any(|imp| has_unsafe(cx, imp));
374 UNSAFE_DERIVE_DESERIALIZE,
376 "you are deriving `serde::Deserialize` on a type that has methods using `unsafe`",
378 "consider implementing `serde::Deserialize` manually. See https://serde.rs/impl-deserialize.html"
384 struct UnsafeVisitor<'a, 'tcx> {
385 cx: &'a LateContext<'tcx>,
389 impl<'tcx> Visitor<'tcx> for UnsafeVisitor<'_, 'tcx> {
390 type Map = Map<'tcx>;
392 fn visit_fn(&mut self, kind: FnKind<'tcx>, decl: &'tcx FnDecl<'_>, body_id: BodyId, span: Span, id: HirId) {
398 if let Some(header) = kind.header();
399 if let Unsafety::Unsafe = header.unsafety;
401 self.has_unsafe = true;
405 walk_fn(self, kind, decl, body_id, span, id);
408 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
413 if let ExprKind::Block(block, _) = expr.kind {
415 BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided)
416 | BlockCheckMode::PushUnsafeBlock(UnsafeSource::UserProvided)
417 | BlockCheckMode::PopUnsafeBlock(UnsafeSource::UserProvided) => {
418 self.has_unsafe = true;
424 walk_expr(self, expr);
427 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
428 NestedVisitorMap::All(self.cx.tcx.hir())