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::def_id::DefId;
7 use rustc_hir::intravisit::{walk_expr, walk_fn, walk_item, FnKind, NestedVisitorMap, Visitor};
9 BlockCheckMode, BodyId, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, TraitRef, UnsafeSource, Unsafety,
11 use rustc_lint::{LateContext, LateLintPass};
12 use rustc_middle::hir::map::Map;
13 use rustc_middle::ty::{self, Ty};
14 use rustc_session::{declare_lint_pass, declare_tool_lint};
15 use rustc_span::source_map::Span;
17 declare_clippy_lint! {
18 /// **What it does:** Checks for deriving `Hash` but implementing `PartialEq`
19 /// explicitly or vice versa.
21 /// **Why is this bad?** The implementation of these traits must agree (for
22 /// example for use with `HashMap`) so it’s probably a bad idea to use a
23 /// default-generated `Hash` implementation with an explicitly defined
24 /// `PartialEq`. In particular, the following must hold for any type:
27 /// k1 == k2 ⇒ hash(k1) == hash(k2)
30 /// **Known problems:** None.
37 /// impl PartialEq for Foo {
41 pub DERIVE_HASH_XOR_EQ,
43 "deriving `Hash` but implementing `PartialEq` explicitly"
46 declare_clippy_lint! {
47 /// **What it does:** Checks for deriving `Ord` but implementing `PartialOrd`
48 /// explicitly or vice versa.
50 /// **Why is this bad?** The implementation of these traits must agree (for
51 /// example for use with `sort`) so it’s probably a bad idea to use a
52 /// default-generated `Ord` implementation with an explicitly defined
53 /// `PartialOrd`. In particular, the following must hold for any type
54 /// implementing `Ord`:
57 /// k1.cmp(&k2) == k1.partial_cmp(&k2).unwrap()
60 /// **Known problems:** None.
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 pub DERIVE_ORD_XOR_PARTIAL_ORD,
94 "deriving `Ord` but implementing `PartialOrd` explicitly"
97 declare_clippy_lint! {
98 /// **What it does:** Checks for explicit `Clone` implementations for `Copy`
101 /// **Why is this bad?** To avoid surprising behaviour, these traits should
102 /// agree and the behaviour of `Copy` cannot be overridden. In almost all
103 /// situations a `Copy` type should have a `Clone` implementation that does
104 /// nothing more than copy the object, which is what `#[derive(Copy, Clone)]`
107 /// **Known problems:** Bounds of generic types are sometimes wrong: https://github.com/rust-lang/rust/issues/26925
114 /// impl Clone for Foo {
118 pub EXPL_IMPL_CLONE_ON_COPY,
120 "implementing `Clone` explicitly on `Copy` types"
123 declare_clippy_lint! {
124 /// **What it does:** Checks for deriving `serde::Deserialize` on a type that
125 /// has methods using `unsafe`.
127 /// **Why is this bad?** Deriving `serde::Deserialize` will create a constructor
128 /// that may violate invariants hold by another constructor.
130 /// **Known problems:** None.
135 /// use serde::Deserialize;
137 /// #[derive(Deserialize)]
143 /// pub fn new() -> Self {
147 /// pub unsafe fn parts() -> (&str, &str) {
148 /// // assumes invariants hold
152 pub UNSAFE_DERIVE_DESERIALIZE,
154 "deriving `serde::Deserialize` on a type that has methods using `unsafe`"
157 declare_lint_pass!(Derive => [
158 EXPL_IMPL_CLONE_ON_COPY,
160 DERIVE_ORD_XOR_PARTIAL_ORD,
161 UNSAFE_DERIVE_DESERIALIZE
164 impl<'tcx> LateLintPass<'tcx> for Derive {
165 fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
166 if let ItemKind::Impl(Impl {
167 of_trait: Some(ref trait_ref),
171 let ty = cx.tcx.type_of(item.def_id);
172 let attrs = cx.tcx.hir().attrs(item.hir_id());
173 let is_automatically_derived = is_automatically_derived(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 let clone_id = match cx.tcx.lang_items().clone_trait() {
297 Some(id) if trait_ref.trait_def_id() == Some(id) => id,
300 let copy_id = match cx.tcx.lang_items().copy_trait() {
304 let (ty_adt, ty_subs) = match *ty.kind() {
305 // Unions can't derive clone.
306 ty::Adt(adt, subs) if !adt.is_union() => (adt, subs),
309 // If the current self type doesn't implement Copy (due to generic constraints), search to see if
310 // there's a Copy impl for any instance of the adt.
311 if !is_copy(cx, ty) {
312 if ty_subs.non_erasable_generics().next().is_some() {
313 let has_copy_impl = cx.tcx.all_local_trait_impls(()).get(©_id).map_or(false, |impls| {
316 .any(|&id| matches!(cx.tcx.type_of(id).kind(), ty::Adt(adt, _) if ty_adt.did == adt.did))
325 // Derive constrains all generic types to requiring Clone. Check if any type is not constrained for
327 if ty_subs.types().any(|ty| !implements_trait(cx, ty, clone_id, &[])) {
333 EXPL_IMPL_CLONE_ON_COPY,
335 "you are implementing `Clone` explicitly on a `Copy` type",
337 "consider deriving `Clone` or removing `Copy`",
341 /// Implementation of the `UNSAFE_DERIVE_DESERIALIZE` lint.
342 fn check_unsafe_derive_deserialize<'tcx>(
343 cx: &LateContext<'tcx>,
345 trait_ref: &TraitRef<'_>,
348 fn item_from_def_id<'tcx>(cx: &LateContext<'tcx>, def_id: DefId) -> &'tcx Item<'tcx> {
349 let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
350 cx.tcx.hir().expect_item(hir_id)
353 fn has_unsafe<'tcx>(cx: &LateContext<'tcx>, item: &'tcx Item<'_>) -> bool {
354 let mut visitor = UnsafeVisitor { cx, has_unsafe: false };
355 walk_item(&mut visitor, item);
360 if let Some(trait_def_id) = trait_ref.trait_def_id();
361 if match_def_path(cx, trait_def_id, &paths::SERDE_DESERIALIZE);
362 if let ty::Adt(def, _) = ty.kind();
363 if let Some(local_def_id) = def.did.as_local();
364 let adt_hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
365 if !is_lint_allowed(cx, UNSAFE_DERIVE_DESERIALIZE, adt_hir_id);
366 if cx.tcx.inherent_impls(def.did)
368 .map(|imp_did| item_from_def_id(cx, *imp_did))
369 .any(|imp| has_unsafe(cx, imp));
373 UNSAFE_DERIVE_DESERIALIZE,
375 "you are deriving `serde::Deserialize` on a type that has methods using `unsafe`",
377 "consider implementing `serde::Deserialize` manually. See https://serde.rs/impl-deserialize.html"
383 struct UnsafeVisitor<'a, 'tcx> {
384 cx: &'a LateContext<'tcx>,
388 impl<'tcx> Visitor<'tcx> for UnsafeVisitor<'_, 'tcx> {
389 type Map = Map<'tcx>;
391 fn visit_fn(&mut self, kind: FnKind<'tcx>, decl: &'tcx FnDecl<'_>, body_id: BodyId, span: Span, id: HirId) {
397 if let Some(header) = kind.header();
398 if let Unsafety::Unsafe = header.unsafety;
400 self.has_unsafe = true;
404 walk_fn(self, kind, decl, body_id, span, id);
407 fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
412 if let ExprKind::Block(block, _) = expr.kind {
413 if let BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) = block.rules {
414 self.has_unsafe = true;
418 walk_expr(self, expr);
421 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
422 NestedVisitorMap::All(self.cx.tcx.hir())