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_allowed, is_automatically_derived, 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_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
{
414 BlockCheckMode
::UnsafeBlock(UnsafeSource
::UserProvided
)
415 | BlockCheckMode
::PushUnsafeBlock(UnsafeSource
::UserProvided
)
416 | BlockCheckMode
::PopUnsafeBlock(UnsafeSource
::UserProvided
) => {
417 self.has_unsafe
= true;
423 walk_expr(self, expr
);
426 fn nested_visit_map(&mut self) -> NestedVisitorMap
<Self::Map
> {
427 NestedVisitorMap
::All(self.cx
.tcx
.hir())