-use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note, span_lint_and_then};
+use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note, span_lint_and_sugg, span_lint_and_then};
use clippy_utils::paths;
-use clippy_utils::ty::{implements_trait, is_copy};
+use clippy_utils::ty::{implements_trait, implements_trait_with_env, is_copy};
use clippy_utils::{is_lint_allowed, match_def_path};
use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::def_id::DefId;
use rustc_hir::intravisit::{walk_expr, walk_fn, walk_item, FnKind, Visitor};
use rustc_hir::{
- BlockCheckMode, BodyId, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, TraitRef, UnsafeSource, Unsafety,
+ self as hir, BlockCheckMode, BodyId, Constness, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, UnsafeSource,
+ Unsafety,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::nested_filter;
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::traits::Reveal;
+use rustc_middle::ty::{
+ self, Binder, BoundConstness, GenericParamDefKind, ImplPolarity, ParamEnv, PredicateKind, TraitPredicate, TraitRef,
+ Ty, TyCtxt,
+};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use rustc_span::sym;
/// types.
///
/// ### Why is this bad?
- /// To avoid surprising behaviour, these traits should
- /// agree and the behaviour of `Copy` cannot be overridden. In almost all
+ /// To avoid surprising behavior, these traits should
+ /// agree and the behavior of `Copy` cannot be overridden. In almost all
/// situations a `Copy` type should have a `Clone` implementation that does
/// nothing more than copy the object, which is what `#[derive(Copy, Clone)]`
/// gets you.
"deriving `serde::Deserialize` on a type that has methods using `unsafe`"
}
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for types that derive `PartialEq` and could implement `Eq`.
+ ///
+ /// ### Why is this bad?
+ /// If a type `T` derives `PartialEq` and all of its members implement `Eq`,
+ /// then `T` can always implement `Eq`. Implementing `Eq` allows `T` to be used
+ /// in APIs that require `Eq` types. It also allows structs containing `T` to derive
+ /// `Eq` themselves.
+ ///
+ /// ### Example
+ /// ```rust
+ /// #[derive(PartialEq)]
+ /// struct Foo {
+ /// i_am_eq: i32,
+ /// i_am_eq_too: Vec<String>,
+ /// }
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// #[derive(PartialEq, Eq)]
+ /// struct Foo {
+ /// i_am_eq: i32,
+ /// i_am_eq_too: Vec<String>,
+ /// }
+ /// ```
+ #[clippy::version = "1.63.0"]
+ pub DERIVE_PARTIAL_EQ_WITHOUT_EQ,
+ nursery,
+ "deriving `PartialEq` on a type that can implement `Eq`, without implementing `Eq`"
+}
+
declare_lint_pass!(Derive => [
EXPL_IMPL_CLONE_ON_COPY,
DERIVE_HASH_XOR_EQ,
DERIVE_ORD_XOR_PARTIAL_ORD,
- UNSAFE_DERIVE_DESERIALIZE
+ UNSAFE_DERIVE_DESERIALIZE,
+ DERIVE_PARTIAL_EQ_WITHOUT_EQ
]);
impl<'tcx> LateLintPass<'tcx> for Derive {
}) = item.kind
{
let ty = cx.tcx.type_of(item.def_id);
- let is_automatically_derived =
- cx.tcx.has_attr(item.def_id.to_def_id(), sym::automatically_derived);
+ let is_automatically_derived = cx.tcx.has_attr(item.def_id.to_def_id(), sym::automatically_derived);
check_hash_peq(cx, item.span, trait_ref, ty, is_automatically_derived);
check_ord_partial_ord(cx, item.span, trait_ref, ty, is_automatically_derived);
if is_automatically_derived {
check_unsafe_derive_deserialize(cx, item, trait_ref, ty);
+ check_partial_eq_without_eq(cx, item.span, trait_ref, ty);
} else {
check_copy_clone(cx, item, trait_ref, ty);
}
fn check_hash_peq<'tcx>(
cx: &LateContext<'tcx>,
span: Span,
- trait_ref: &TraitRef<'_>,
+ trait_ref: &hir::TraitRef<'_>,
ty: Ty<'tcx>,
hash_is_automatically_derived: bool,
) {
fn check_ord_partial_ord<'tcx>(
cx: &LateContext<'tcx>,
span: Span,
- trait_ref: &TraitRef<'_>,
+ trait_ref: &hir::TraitRef<'_>,
ty: Ty<'tcx>,
ord_is_automatically_derived: bool,
) {
}
/// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint.
-fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &TraitRef<'_>, ty: Ty<'tcx>) {
+fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &hir::TraitRef<'_>, ty: Ty<'tcx>) {
let clone_id = match cx.tcx.lang_items().clone_trait() {
Some(id) if trait_ref.trait_def_id() == Some(id) => id,
_ => return,
};
- let copy_id = match cx.tcx.lang_items().copy_trait() {
- Some(id) => id,
- None => return,
- };
+ let Some(copy_id) = cx.tcx.lang_items().copy_trait() else { return };
let (ty_adt, ty_subs) = match *ty.kind() {
// Unions can't derive clone.
ty::Adt(adt, subs) if !adt.is_union() => (adt, subs),
fn check_unsafe_derive_deserialize<'tcx>(
cx: &LateContext<'tcx>,
item: &Item<'_>,
- trait_ref: &TraitRef<'_>,
+ trait_ref: &hir::TraitRef<'_>,
ty: Ty<'tcx>,
) {
fn has_unsafe<'tcx>(cx: &LateContext<'tcx>, item: &'tcx Item<'_>) -> bool {
impl<'tcx> Visitor<'tcx> for UnsafeVisitor<'_, 'tcx> {
type NestedFilter = nested_filter::All;
- fn visit_fn(&mut self, kind: FnKind<'tcx>, decl: &'tcx FnDecl<'_>, body_id: BodyId, span: Span, id: HirId) {
+ fn visit_fn(&mut self, kind: FnKind<'tcx>, decl: &'tcx FnDecl<'_>, body_id: BodyId, _: Span, id: HirId) {
if self.has_unsafe {
return;
}
}
}
- walk_fn(self, kind, decl, body_id, span, id);
+ walk_fn(self, kind, decl, body_id, id);
}
fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
self.cx.tcx.hir()
}
}
+
+/// Implementation of the `DERIVE_PARTIAL_EQ_WITHOUT_EQ` lint.
+fn check_partial_eq_without_eq<'tcx>(cx: &LateContext<'tcx>, span: Span, trait_ref: &hir::TraitRef<'_>, ty: Ty<'tcx>) {
+ if_chain! {
+ if let ty::Adt(adt, substs) = ty.kind();
+ if cx.tcx.visibility(adt.did()).is_public();
+ if let Some(eq_trait_def_id) = cx.tcx.get_diagnostic_item(sym::Eq);
+ if let Some(def_id) = trait_ref.trait_def_id();
+ if cx.tcx.is_diagnostic_item(sym::PartialEq, def_id);
+ let param_env = param_env_for_derived_eq(cx.tcx, adt.did(), eq_trait_def_id);
+ if !implements_trait_with_env(cx.tcx, param_env, ty, eq_trait_def_id, &[]);
+ // If all of our fields implement `Eq`, we can implement `Eq` too
+ if adt
+ .all_fields()
+ .map(|f| f.ty(cx.tcx, substs))
+ .all(|ty| implements_trait_with_env(cx.tcx, param_env, ty, eq_trait_def_id, &[]));
+ then {
+ span_lint_and_sugg(
+ cx,
+ DERIVE_PARTIAL_EQ_WITHOUT_EQ,
+ span.ctxt().outer_expn_data().call_site,
+ "you are deriving `PartialEq` and can implement `Eq`",
+ "consider deriving `Eq` as well",
+ "PartialEq, Eq".to_string(),
+ Applicability::MachineApplicable,
+ )
+ }
+ }
+}
+
+/// Creates the `ParamEnv` used for the give type's derived `Eq` impl.
+fn param_env_for_derived_eq(tcx: TyCtxt<'_>, did: DefId, eq_trait_id: DefId) -> ParamEnv<'_> {
+ // Initial map from generic index to param def.
+ // Vec<(param_def, needs_eq)>
+ let mut params = tcx
+ .generics_of(did)
+ .params
+ .iter()
+ .map(|p| (p, matches!(p.kind, GenericParamDefKind::Type { .. })))
+ .collect::<Vec<_>>();
+
+ let ty_predicates = tcx.predicates_of(did).predicates;
+ for (p, _) in ty_predicates {
+ if let PredicateKind::Trait(p) = p.kind().skip_binder()
+ && p.trait_ref.def_id == eq_trait_id
+ && let ty::Param(self_ty) = p.trait_ref.self_ty().kind()
+ && p.constness == BoundConstness::NotConst
+ {
+ // Flag types which already have an `Eq` bound.
+ params[self_ty.index as usize].1 = false;
+ }
+ }
+
+ ParamEnv::new(
+ tcx.mk_predicates(ty_predicates.iter().map(|&(p, _)| p).chain(
+ params.iter().filter(|&&(_, needs_eq)| needs_eq).map(|&(param, _)| {
+ tcx.mk_predicate(Binder::dummy(PredicateKind::Trait(TraitPredicate {
+ trait_ref: TraitRef::new(
+ eq_trait_id,
+ tcx.mk_substs(std::iter::once(tcx.mk_param_from_def(param))),
+ ),
+ constness: BoundConstness::NotConst,
+ polarity: ImplPolarity::Positive,
+ })))
+ }),
+ )),
+ Reveal::UserFacing,
+ Constness::NotConst,
+ )
+}
projects / rust.git / blobdiff