Split out each lint into a separate module

Best viewed with `git diff --color-moved`

Author: ada4a

clippy_lints/src/derive/derive_ord_xor_partial_ord.rs

@@ -0,0 +1,50 @@
+use clippy_utils::diagnostics::span_lint_and_then;
+use rustc_hir as hir;
+use rustc_lint::LateContext;
+use rustc_middle::ty::Ty;
+use rustc_span::{Span, sym};
+
+use super::DERIVE_ORD_XOR_PARTIAL_ORD;
+
+/// Implementation of the `DERIVE_ORD_XOR_PARTIAL_ORD` lint.
+pub(super) fn check<'tcx>(
+    cx: &LateContext<'tcx>,
+    span: Span,
+    trait_ref: &hir::TraitRef<'_>,
+    ty: Ty<'tcx>,
+    ord_is_automatically_derived: bool,
+) {
+    if let Some(ord_trait_def_id) = cx.tcx.get_diagnostic_item(sym::Ord)
+        && let Some(partial_ord_trait_def_id) = cx.tcx.lang_items().partial_ord_trait()
+        && let Some(def_id) = &trait_ref.trait_def_id()
+        && *def_id == ord_trait_def_id
+    {
+        // Look for the PartialOrd implementations for `ty`
+        cx.tcx.for_each_relevant_impl(partial_ord_trait_def_id, ty, |impl_id| {
+            let partial_ord_is_automatically_derived = cx.tcx.is_automatically_derived(impl_id);
+
+            if partial_ord_is_automatically_derived == ord_is_automatically_derived {
+                return;
+            }
+
+            let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
+
+            // Only care about `impl PartialOrd<Foo> for Foo`
+            // For `impl PartialOrd<B> for A, input_types is [A, B]
+            if trait_ref.instantiate_identity().args.type_at(1) == ty {
+                let mess = if partial_ord_is_automatically_derived {
+                    "you are implementing `Ord` explicitly but have derived `PartialOrd`"
+                } else {
+                    "you are deriving `Ord` but have implemented `PartialOrd` explicitly"
+                };
+
+                span_lint_and_then(cx, DERIVE_ORD_XOR_PARTIAL_ORD, span, mess, |diag| {
+                    if let Some(local_def_id) = impl_id.as_local() {
+                        let hir_id = cx.tcx.local_def_id_to_hir_id(local_def_id);
+                        diag.span_note(cx.tcx.hir_span(hir_id), "`PartialOrd` implemented here");
+                    }
+                });
+            }
+        });
+    }
+}

clippy_lints/src/derive/derive_partial_eq_without_eq.rs

@@ -0,0 +1,87 @@
+use clippy_utils::diagnostics::span_lint_hir_and_then;
+use clippy_utils::has_non_exhaustive_attr;
+use clippy_utils::ty::implements_trait_with_env;
+use rustc_errors::Applicability;
+use rustc_hir as hir;
+use rustc_hir::def_id::DefId;
+use rustc_lint::LateContext;
+use rustc_middle::ty::{self, ClauseKind, GenericParamDefKind, ParamEnv, TraitPredicate, Ty, TyCtxt, Upcast};
+use rustc_span::{Span, sym};
+
+use super::DERIVE_PARTIAL_EQ_WITHOUT_EQ;
+
+/// Implementation of the `DERIVE_PARTIAL_EQ_WITHOUT_EQ` lint.
+pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, span: Span, trait_ref: &hir::TraitRef<'_>, ty: Ty<'tcx>) {
+    if let ty::Adt(adt, args) = ty.kind()
+        && cx.tcx.visibility(adt.did()).is_public()
+        && let Some(eq_trait_def_id) = cx.tcx.get_diagnostic_item(sym::Eq)
+        && let Some(def_id) = trait_ref.trait_def_id()
+        && cx.tcx.is_diagnostic_item(sym::PartialEq, def_id)
+        && !has_non_exhaustive_attr(cx.tcx, *adt)
+        && !ty_implements_eq_trait(cx.tcx, ty, eq_trait_def_id)
+        && let typing_env = typing_env_for_derived_eq(cx.tcx, adt.did(), eq_trait_def_id)
+        && let Some(local_def_id) = adt.did().as_local()
+        // If all of our fields implement `Eq`, we can implement `Eq` too
+        && adt
+            .all_fields()
+            .map(|f| f.ty(cx.tcx, args))
+            .all(|ty| implements_trait_with_env(cx.tcx, typing_env, ty, eq_trait_def_id, None, &[]))
+    {
+        span_lint_hir_and_then(
+            cx,
+            DERIVE_PARTIAL_EQ_WITHOUT_EQ,
+            cx.tcx.local_def_id_to_hir_id(local_def_id),
+            span.ctxt().outer_expn_data().call_site,
+            "you are deriving `PartialEq` and can implement `Eq`",
+            |diag| {
+                diag.span_suggestion(
+                    span.ctxt().outer_expn_data().call_site,
+                    "consider deriving `Eq` as well",
+                    "PartialEq, Eq",
+                    Applicability::MachineApplicable,
+                );
+            },
+        );
+    }
+}
+
+fn ty_implements_eq_trait<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, eq_trait_id: DefId) -> bool {
+    tcx.non_blanket_impls_for_ty(eq_trait_id, ty).next().is_some()
+}
+
+/// Creates the `ParamEnv` used for the given type's derived `Eq` impl.
+fn typing_env_for_derived_eq(tcx: TyCtxt<'_>, did: DefId, eq_trait_id: DefId) -> ty::TypingEnv<'_> {
+    // Initial map from generic index to param def.
+    // Vec<(param_def, needs_eq)>
+    let mut params = tcx
+        .generics_of(did)
+        .own_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 ClauseKind::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()
+        {
+            // Flag types which already have an `Eq` bound.
+            params[self_ty.index as usize].1 = false;
+        }
+    }
+
+    let param_env = ParamEnv::new(tcx.mk_clauses_from_iter(ty_predicates.iter().map(|&(p, _)| p).chain(
+        params.iter().filter(|&&(_, needs_eq)| needs_eq).map(|&(param, _)| {
+            ClauseKind::Trait(TraitPredicate {
+                trait_ref: ty::TraitRef::new(tcx, eq_trait_id, [tcx.mk_param_from_def(param)]),
+                polarity: ty::PredicatePolarity::Positive,
+            })
+            .upcast(tcx)
+        }),
+    )));
+    ty::TypingEnv {
+        typing_mode: ty::TypingMode::non_body_analysis(),
+        param_env,
+    }
+}

clippy_lints/src/derive/derived_hash_with_manual_eq.rs

@@ -0,0 +1,49 @@
+use clippy_utils::diagnostics::span_lint_and_then;
+use rustc_hir as hir;
+use rustc_lint::LateContext;
+use rustc_middle::ty::Ty;
+use rustc_span::{Span, sym};
+
+use super::DERIVED_HASH_WITH_MANUAL_EQ;
+
+/// Implementation of the `DERIVED_HASH_WITH_MANUAL_EQ` lint.
+pub(super) fn check<'tcx>(
+    cx: &LateContext<'tcx>,
+    span: Span,
+    trait_ref: &hir::TraitRef<'_>,
+    ty: Ty<'tcx>,
+    hash_is_automatically_derived: bool,
+) {
+    if let Some(peq_trait_def_id) = cx.tcx.lang_items().eq_trait()
+        && let Some(def_id) = trait_ref.trait_def_id()
+        && cx.tcx.is_diagnostic_item(sym::Hash, def_id)
+    {
+        // Look for the PartialEq implementations for `ty`
+        cx.tcx.for_each_relevant_impl(peq_trait_def_id, ty, |impl_id| {
+            let peq_is_automatically_derived = cx.tcx.is_automatically_derived(impl_id);
+
+            if !hash_is_automatically_derived || peq_is_automatically_derived {
+                return;
+            }
+
+            let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
+
+            // Only care about `impl PartialEq<Foo> for Foo`
+            // For `impl PartialEq<B> for A, input_types is [A, B]
+            if trait_ref.instantiate_identity().args.type_at(1) == ty {
+                span_lint_and_then(
+                    cx,
+                    DERIVED_HASH_WITH_MANUAL_EQ,
+                    span,
+                    "you are deriving `Hash` but have implemented `PartialEq` explicitly",
+                    |diag| {
+                        if let Some(local_def_id) = impl_id.as_local() {
+                            let hir_id = cx.tcx.local_def_id_to_hir_id(local_def_id);
+                            diag.span_note(cx.tcx.hir_span(hir_id), "`PartialEq` implemented here");
+                        }
+                    },
+                );
+            }
+        });
+    }
+}

clippy_lints/src/derive/expl_impl_clone_on_copy.rs

@@ -0,0 +1,65 @@
+use clippy_utils::diagnostics::span_lint_and_note;
+use clippy_utils::ty::{implements_trait, is_copy};
+use rustc_hir::{self as hir, Item};
+use rustc_lint::LateContext;
+use rustc_middle::ty::{self, GenericArgKind, Ty};
+
+use super::EXPL_IMPL_CLONE_ON_COPY;
+
+/// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint.
+pub(super) fn check<'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 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),
+        _ => return,
+    };
+    // If the current self type doesn't implement Copy (due to generic constraints), search to see if
+    // there's a Copy impl for any instance of the adt.
+    if !is_copy(cx, ty) {
+        if ty_subs.non_erasable_generics().next().is_some() {
+            let has_copy_impl = cx.tcx.local_trait_impls(copy_id).iter().any(|&id| {
+                matches!(cx.tcx.type_of(id).instantiate_identity().kind(), ty::Adt(adt, _)
+                                        if ty_adt.did() == adt.did())
+            });
+            if !has_copy_impl {
+                return;
+            }
+        } else {
+            return;
+        }
+    }
+    // Derive constrains all generic types to requiring Clone. Check if any type is not constrained for
+    // this impl.
+    if ty_subs.types().any(|ty| !implements_trait(cx, ty, clone_id, &[])) {
+        return;
+    }
+    // `#[repr(packed)]` structs with type/const parameters can't derive `Clone`.
+    // https://github.com/rust-lang/rust-clippy/issues/10188
+    if ty_adt.repr().packed()
+        && ty_subs
+            .iter()
+            .any(|arg| matches!(arg.kind(), GenericArgKind::Type(_) | GenericArgKind::Const(_)))
+    {
+        return;
+    }
+    // The presence of `unsafe` fields prevents deriving `Clone` automatically
+    if ty_adt.all_fields().any(|f| f.safety.is_unsafe()) {
+        return;
+    }
+
+    span_lint_and_note(
+        cx,
+        EXPL_IMPL_CLONE_ON_COPY,
+        item.span,
+        "you are implementing `Clone` explicitly on a `Copy` type",
+        Some(item.span),
+        "consider deriving `Clone` or removing `Copy`",
+    );
+}