-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::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, 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::ty::subst::GenericArg;
+use rustc_middle::ty::{self, BoundConstness, ImplPolarity, ParamEnv, PredicateKind, TraitPredicate, TraitRef, Ty};
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 = "1.62.0"]
+ pub DERIVE_PARTIAL_EQ_WITHOUT_EQ,
+ style,
+ "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,
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 {
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 let Some(eq_trait_def_id) = cx.tcx.get_diagnostic_item(sym::Eq);
+ if let Some(peq_trait_def_id) = cx.tcx.get_diagnostic_item(sym::PartialEq);
+ if let Some(def_id) = trait_ref.trait_def_id();
+ if cx.tcx.is_diagnostic_item(sym::PartialEq, def_id);
+ // New `ParamEnv` replacing `T: PartialEq` with `T: Eq`
+ let param_env = ParamEnv::new(
+ cx.tcx.mk_predicates(cx.param_env.caller_bounds().iter().map(|p| {
+ let kind = p.kind();
+ match kind.skip_binder() {
+ PredicateKind::Trait(p)
+ if p.trait_ref.def_id == peq_trait_def_id
+ && p.trait_ref.substs.get(0) == p.trait_ref.substs.get(1)
+ && matches!(p.trait_ref.self_ty().kind(), ty::Param(_))
+ && p.constness == BoundConstness::NotConst
+ && p.polarity == ImplPolarity::Positive =>
+ {
+ cx.tcx.mk_predicate(kind.rebind(PredicateKind::Trait(TraitPredicate {
+ trait_ref: TraitRef::new(
+ eq_trait_def_id,
+ cx.tcx.mk_substs([GenericArg::from(p.trait_ref.self_ty())].into_iter()),
+ ),
+ constness: BoundConstness::NotConst,
+ polarity: ImplPolarity::Positive,
+ })))
+ },
+ _ => p,
+ }
+ })),
+ cx.param_env.reveal(),
+ cx.param_env.constness(),
+ );
+ if !implements_trait_with_env(cx.tcx, param_env, ty, eq_trait_def_id, substs);
+ then {
+ // If all of our fields implement `Eq`, we can implement `Eq` too
+ for variant in adt.variants() {
+ for field in &variant.fields {
+ let ty = field.ty(cx.tcx, substs);
+
+ if !implements_trait(cx, ty, eq_trait_def_id, substs) {
+ return;
+ }
+ }
+ }
+
+ 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,
+ )
+ }
+ }
+}
projects / rust.git / blobdiff