[rustc.git] / src / tools / clippy / clippy_lints / src / derive.rs

use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note, span_lint_and_then};
use clippy_utils::paths;
use clippy_utils::ty::{implements_trait, is_copy};
use clippy_utils::{is_automatically_derived, is_lint_allowed, match_def_path};
use if_chain::if_chain;
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,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::nested_filter;
use rustc_middle::ty::{self, Ty};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use rustc_span::sym;

declare_clippy_lint! {
    /// ### What it does
    /// Checks for deriving `Hash` but implementing `PartialEq`
    /// explicitly or vice versa.
    ///
    /// ### Why is this bad?
    /// The implementation of these traits must agree (for
    /// example for use with `HashMap`) so it’s probably a bad idea to use a
    /// default-generated `Hash` implementation with an explicitly defined
    /// `PartialEq`. In particular, the following must hold for any type:
    ///
    /// ```text
    /// k1 == k2 ⇒ hash(k1) == hash(k2)
    /// ```
    ///
    /// ### Example
    /// ```ignore
    /// #[derive(Hash)]
    /// struct Foo;
    ///
    /// impl PartialEq for Foo {
    ///     ...
    /// }
    /// ```
    #[clippy::version = "pre 1.29.0"]
    pub DERIVE_HASH_XOR_EQ,
    correctness,
    "deriving `Hash` but implementing `PartialEq` explicitly"
}

declare_clippy_lint! {
    /// ### What it does
    /// Checks for deriving `Ord` but implementing `PartialOrd`
    /// explicitly or vice versa.
    ///
    /// ### Why is this bad?
    /// The implementation of these traits must agree (for
    /// example for use with `sort`) so it’s probably a bad idea to use a
    /// default-generated `Ord` implementation with an explicitly defined
    /// `PartialOrd`. In particular, the following must hold for any type
    /// implementing `Ord`:
    ///
    /// ```text
    /// k1.cmp(&k2) == k1.partial_cmp(&k2).unwrap()
    /// ```
    ///
    /// ### Example
    /// ```rust,ignore
    /// #[derive(Ord, PartialEq, Eq)]
    /// struct Foo;
    ///
    /// impl PartialOrd for Foo {
    ///     ...
    /// }
    /// ```
    /// Use instead:
    /// ```rust,ignore
    /// #[derive(PartialEq, Eq)]
    /// struct Foo;
    ///
    /// impl PartialOrd for Foo {
    ///     fn partial_cmp(&self, other: &Foo) -> Option<Ordering> {
    ///        Some(self.cmp(other))
    ///     }
    /// }
    ///
    /// impl Ord for Foo {
    ///     ...
    /// }
    /// ```
    /// or, if you don't need a custom ordering:
    /// ```rust,ignore
    /// #[derive(Ord, PartialOrd, PartialEq, Eq)]
    /// struct Foo;
    /// ```
    #[clippy::version = "1.47.0"]
    pub DERIVE_ORD_XOR_PARTIAL_ORD,
    correctness,
    "deriving `Ord` but implementing `PartialOrd` explicitly"
}

declare_clippy_lint! {
    /// ### What it does
    /// Checks for explicit `Clone` implementations for `Copy`
    /// types.
    ///
    /// ### Why is this bad?
    /// To avoid surprising behaviour, these traits should
    /// agree and the behaviour 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.
    ///
    /// ### Example
    /// ```rust,ignore
    /// #[derive(Copy)]
    /// struct Foo;
    ///
    /// impl Clone for Foo {
    ///     // ..
    /// }
    /// ```
    #[clippy::version = "pre 1.29.0"]
    pub EXPL_IMPL_CLONE_ON_COPY,
    pedantic,
    "implementing `Clone` explicitly on `Copy` types"
}

declare_clippy_lint! {
    /// ### What it does
    /// Checks for deriving `serde::Deserialize` on a type that
    /// has methods using `unsafe`.
    ///
    /// ### Why is this bad?
    /// Deriving `serde::Deserialize` will create a constructor
    /// that may violate invariants hold by another constructor.
    ///
    /// ### Example
    /// ```rust,ignore
    /// use serde::Deserialize;
    ///
    /// #[derive(Deserialize)]
    /// pub struct Foo {
    ///     // ..
    /// }
    ///
    /// impl Foo {
    ///     pub fn new() -> Self {
    ///         // setup here ..
    ///     }
    ///
    ///     pub unsafe fn parts() -> (&str, &str) {
    ///         // assumes invariants hold
    ///     }
    /// }
    /// ```
    #[clippy::version = "1.45.0"]
    pub UNSAFE_DERIVE_DESERIALIZE,
    pedantic,
    "deriving `serde::Deserialize` on a type that has methods using `unsafe`"
}

declare_lint_pass!(Derive => [
    EXPL_IMPL_CLONE_ON_COPY,
    DERIVE_HASH_XOR_EQ,
    DERIVE_ORD_XOR_PARTIAL_ORD,
    UNSAFE_DERIVE_DESERIALIZE
]);

impl<'tcx> LateLintPass<'tcx> for Derive {
    fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
        if let ItemKind::Impl(Impl {
            of_trait: Some(ref trait_ref),
            ..
        }) = item.kind
        {
            let ty = cx.tcx.type_of(item.def_id);
            let attrs = cx.tcx.hir().attrs(item.hir_id());
            let is_automatically_derived = is_automatically_derived(attrs);

            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);
            } else {
                check_copy_clone(cx, item, trait_ref, ty);
            }
        }
    }
}

/// Implementation of the `DERIVE_HASH_XOR_EQ` lint.
fn check_hash_peq<'tcx>(
    cx: &LateContext<'tcx>,
    span: Span,
    trait_ref: &TraitRef<'_>,
    ty: Ty<'tcx>,
    hash_is_automatically_derived: bool,
) {
    if_chain! {
        if let Some(peq_trait_def_id) = cx.tcx.lang_items().eq_trait();
        if let Some(def_id) = trait_ref.trait_def_id();
        if cx.tcx.is_diagnostic_item(sym::Hash, def_id);
        then {
            // 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 = is_automatically_derived(cx.tcx.get_attrs(impl_id));

                if peq_is_automatically_derived == hash_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.substs.type_at(1) == ty {
                    let mess = if peq_is_automatically_derived {
                        "you are implementing `Hash` explicitly but have derived `PartialEq`"
                    } else {
                        "you are deriving `Hash` but have implemented `PartialEq` explicitly"
                    };

                    span_lint_and_then(
                        cx,
                        DERIVE_HASH_XOR_EQ,
                        span,
                        mess,
                        |diag| {
                            if let Some(local_def_id) = impl_id.as_local() {
                                let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
                                diag.span_note(
                                    cx.tcx.hir().span(hir_id),
                                    "`PartialEq` implemented here"
                                );
                            }
                        }
                    );
                }
            });
        }
    }
}

/// Implementation of the `DERIVE_ORD_XOR_PARTIAL_ORD` lint.
fn check_ord_partial_ord<'tcx>(
    cx: &LateContext<'tcx>,
    span: Span,
    trait_ref: &TraitRef<'_>,
    ty: Ty<'tcx>,
    ord_is_automatically_derived: bool,
) {
    if_chain! {
        if let Some(ord_trait_def_id) = cx.tcx.get_diagnostic_item(sym::Ord);
        if let Some(partial_ord_trait_def_id) = cx.tcx.lang_items().partial_ord_trait();
        if let Some(def_id) = &trait_ref.trait_def_id();
        if *def_id == ord_trait_def_id;
        then {
            // 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 = is_automatically_derived(cx.tcx.get_attrs(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.substs.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.hir().local_def_id_to_hir_id(local_def_id);
                                diag.span_note(
                                    cx.tcx.hir().span(hir_id),
                                    "`PartialOrd` implemented here"
                                );
                            }
                        }
                    );
                }
            });
        }
    }
}

/// 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>) {
    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 (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.all_local_trait_impls(()).get(&copy_id).map_or(false, |impls| {
                impls
                    .iter()
                    .any(|&id| matches!(cx.tcx.type_of(id).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;
    }

    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`",
    );
}

/// Implementation of the `UNSAFE_DERIVE_DESERIALIZE` lint.
fn check_unsafe_derive_deserialize<'tcx>(
    cx: &LateContext<'tcx>,
    item: &Item<'_>,
    trait_ref: &TraitRef<'_>,
    ty: Ty<'tcx>,
) {
    fn has_unsafe<'tcx>(cx: &LateContext<'tcx>, item: &'tcx Item<'_>) -> bool {
        let mut visitor = UnsafeVisitor { cx, has_unsafe: false };
        walk_item(&mut visitor, item);
        visitor.has_unsafe
    }

    if_chain! {
        if let Some(trait_def_id) = trait_ref.trait_def_id();
        if match_def_path(cx, trait_def_id, &paths::SERDE_DESERIALIZE);
        if let ty::Adt(def, _) = ty.kind();
        if let Some(local_def_id) = def.did().as_local();
        let adt_hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
        if !is_lint_allowed(cx, UNSAFE_DERIVE_DESERIALIZE, adt_hir_id);
        if cx.tcx.inherent_impls(def.did())
            .iter()
            .map(|imp_did| cx.tcx.hir().expect_item(imp_did.expect_local()))
            .any(|imp| has_unsafe(cx, imp));
        then {
            span_lint_and_help(
                cx,
                UNSAFE_DERIVE_DESERIALIZE,
                item.span,
                "you are deriving `serde::Deserialize` on a type that has methods using `unsafe`",
                None,
                "consider implementing `serde::Deserialize` manually. See https://serde.rs/impl-deserialize.html"
            );
        }
    }
}

struct UnsafeVisitor<'a, 'tcx> {
    cx: &'a LateContext<'tcx>,
    has_unsafe: 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) {
        if self.has_unsafe {
            return;
        }

        if_chain! {
            if let Some(header) = kind.header();
            if header.unsafety == Unsafety::Unsafe;
            then {
                self.has_unsafe = true;
            }
        }

        walk_fn(self, kind, decl, body_id, span, id);
    }

    fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
        if self.has_unsafe {
            return;
        }

        if let ExprKind::Block(block, _) = expr.kind {
            if block.rules == BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) {
                self.has_unsafe = true;
            }
        }

        walk_expr(self, expr);
    }

    fn nested_visit_map(&mut self) -> Self::Map {
        self.cx.tcx.hir()
    }
}
Commit	Line	Data
cdc7bbd5 XL	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};
ee023bcb	4	use clippy_utils::{is_automatically_derived, is_lint_allowed, match_def_path};
f20569fa	5	use if_chain::if_chain;
5099ac24	6	use rustc_hir::intravisit::{walk_expr, walk_fn, walk_item, FnKind, Visitor};
f20569fa XL	7	use rustc_hir::{
	8	BlockCheckMode, BodyId, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, TraitRef, UnsafeSource, Unsafety,
	9	};
	10	use rustc_lint::{LateContext, LateLintPass};
5099ac24	11	use rustc_middle::hir::nested_filter;
f20569fa XL	12	use rustc_middle::ty::{self, Ty};
f20569fa XL	13	use rustc_session::{declare_lint_pass, declare_tool_lint};
17df50a5	14	use rustc_span::source_map::Span;
ee023bcb	15	use rustc_span::sym;
f20569fa XL	16
f20569fa XL	17	declare_clippy_lint! {
94222f64 XL	18	/// ### What it does
94222f64 XL	19	/// Checks for deriving `Hash` but implementing `PartialEq`
f20569fa XL	20	/// explicitly or vice versa.
f20569fa XL	21	///
94222f64 XL	22	/// ### Why is this bad?
94222f64 XL	23	/// The implementation of these traits must agree (for
f20569fa XL	24	/// example for use with `HashMap`) so it’s probably a bad idea to use a
	25	/// default-generated `Hash` implementation with an explicitly defined
	26	/// `PartialEq`. In particular, the following must hold for any type:
	27	///
	28	/// ```text
	29	/// k1 == k2 ⇒ hash(k1) == hash(k2)
	30	/// ```
	31	///
94222f64	32	/// ### Example
f20569fa XL	33	/// ```ignore
	34	/// #[derive(Hash)]
	35	/// struct Foo;
	36	///
	37	/// impl PartialEq for Foo {
	38	/// ...
	39	/// }
	40	/// ```
a2a8927a	41	#[clippy::version = "pre 1.29.0"]
f20569fa XL	42	pub DERIVE_HASH_XOR_EQ,
	43	correctness,
	44	"deriving `Hash` but implementing `PartialEq` explicitly"
	45	}
	46
	47	declare_clippy_lint! {
94222f64 XL	48	/// ### What it does
94222f64 XL	49	/// Checks for deriving `Ord` but implementing `PartialOrd`
f20569fa XL	50	/// explicitly or vice versa.
f20569fa XL	51	///
94222f64 XL	52	/// ### Why is this bad?
94222f64 XL	53	/// The implementation of these traits must agree (for
f20569fa XL	54	/// example for use with `sort`) so it’s probably a bad idea to use a
	55	/// default-generated `Ord` implementation with an explicitly defined
	56	/// `PartialOrd`. In particular, the following must hold for any type
	57	/// implementing `Ord`:
	58	///
	59	/// ```text
	60	/// k1.cmp(&k2) == k1.partial_cmp(&k2).unwrap()
	61	/// ```
	62	///
94222f64	63	/// ### Example
f20569fa XL	64	/// ```rust,ignore
	65	/// #[derive(Ord, PartialEq, Eq)]
	66	/// struct Foo;
	67	///
	68	/// impl PartialOrd for Foo {
	69	/// ...
	70	/// }
	71	/// ```
	72	/// Use instead:
	73	/// ```rust,ignore
	74	/// #[derive(PartialEq, Eq)]
	75	/// struct Foo;
	76	///
	77	/// impl PartialOrd for Foo {
	78	/// fn partial_cmp(&self, other: &Foo) -> Option<Ordering> {
	79	/// Some(self.cmp(other))
	80	/// }
	81	/// }
	82	///
	83	/// impl Ord for Foo {
	84	/// ...
	85	/// }
	86	/// ```
	87	/// or, if you don't need a custom ordering:
	88	/// ```rust,ignore
	89	/// #[derive(Ord, PartialOrd, PartialEq, Eq)]
	90	/// struct Foo;
	91	/// ```
a2a8927a	92	#[clippy::version = "1.47.0"]
f20569fa XL	93	pub DERIVE_ORD_XOR_PARTIAL_ORD,
	94	correctness,
	95	"deriving `Ord` but implementing `PartialOrd` explicitly"
	96	}
	97
	98	declare_clippy_lint! {
94222f64 XL	99	/// ### What it does
94222f64 XL	100	/// Checks for explicit `Clone` implementations for `Copy`
f20569fa XL	101	/// types.
f20569fa XL	102	///
94222f64 XL	103	/// ### Why is this bad?
94222f64 XL	104	/// To avoid surprising behaviour, these traits should
f20569fa XL	105	/// agree and the behaviour of `Copy` cannot be overridden. In almost all
	106	/// situations a `Copy` type should have a `Clone` implementation that does
	107	/// nothing more than copy the object, which is what `#[derive(Copy, Clone)]`
	108	/// gets you.
	109	///
94222f64	110	/// ### Example
f20569fa XL	111	/// ```rust,ignore
	112	/// #[derive(Copy)]
	113	/// struct Foo;
	114	///
	115	/// impl Clone for Foo {
	116	/// // ..
	117	/// }
	118	/// ```
a2a8927a	119	#[clippy::version = "pre 1.29.0"]
f20569fa XL	120	pub EXPL_IMPL_CLONE_ON_COPY,
	121	pedantic,
	122	"implementing `Clone` explicitly on `Copy` types"
	123	}
	124
	125	declare_clippy_lint! {
94222f64 XL	126	/// ### What it does
94222f64 XL	127	/// Checks for deriving `serde::Deserialize` on a type that
f20569fa XL	128	/// has methods using `unsafe`.
f20569fa XL	129	///
94222f64 XL	130	/// ### Why is this bad?
94222f64 XL	131	/// Deriving `serde::Deserialize` will create a constructor
f20569fa XL	132	/// that may violate invariants hold by another constructor.
f20569fa XL	133	///
94222f64	134	/// ### Example
f20569fa XL	135	/// ```rust,ignore
	136	/// use serde::Deserialize;
	137	///
	138	/// #[derive(Deserialize)]
	139	/// pub struct Foo {
	140	/// // ..
	141	/// }
	142	///
	143	/// impl Foo {
	144	/// pub fn new() -> Self {
	145	/// // setup here ..
	146	/// }
	147	///
	148	/// pub unsafe fn parts() -> (&str, &str) {
	149	/// // assumes invariants hold
	150	/// }
	151	/// }
	152	/// ```
a2a8927a	153	#[clippy::version = "1.45.0"]
f20569fa XL	154	pub UNSAFE_DERIVE_DESERIALIZE,
	155	pedantic,
	156	"deriving `serde::Deserialize` on a type that has methods using `unsafe`"
	157	}
	158
	159	declare_lint_pass!(Derive => [
	160	EXPL_IMPL_CLONE_ON_COPY,
	161	DERIVE_HASH_XOR_EQ,
	162	DERIVE_ORD_XOR_PARTIAL_ORD,
	163	UNSAFE_DERIVE_DESERIALIZE
	164	]);
	165
	166	impl<'tcx> LateLintPass<'tcx> for Derive {
	167	fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
	168	if let ItemKind::Impl(Impl {
	169	of_trait: Some(ref trait_ref),
	170	..
	171	}) = item.kind
	172	{
	173	let ty = cx.tcx.type_of(item.def_id);
	174	let attrs = cx.tcx.hir().attrs(item.hir_id());
	175	let is_automatically_derived = is_automatically_derived(attrs);
	176
	177	check_hash_peq(cx, item.span, trait_ref, ty, is_automatically_derived);
	178	check_ord_partial_ord(cx, item.span, trait_ref, ty, is_automatically_derived);
	179
	180	if is_automatically_derived {
	181	check_unsafe_derive_deserialize(cx, item, trait_ref, ty);
	182	} else {
	183	check_copy_clone(cx, item, trait_ref, ty);
	184	}
	185	}
	186	}
	187	}
	188
	189	/// Implementation of the `DERIVE_HASH_XOR_EQ` lint.
	190	fn check_hash_peq<'tcx>(
	191	cx: &LateContext<'tcx>,
	192	span: Span,
	193	trait_ref: &TraitRef<'_>,
	194	ty: Ty<'tcx>,
	195	hash_is_automatically_derived: bool,
	196	) {
	197	if_chain! {
	198	if let Some(peq_trait_def_id) = cx.tcx.lang_items().eq_trait();
	199	if let Some(def_id) = trait_ref.trait_def_id();
ee023bcb	200	if cx.tcx.is_diagnostic_item(sym::Hash, def_id);
f20569fa XL	201	then {
	202	// Look for the PartialEq implementations for `ty`
	203	cx.tcx.for_each_relevant_impl(peq_trait_def_id, ty, \|impl_id\| {
cdc7bbd5	204	let peq_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
f20569fa XL	205
	206	if peq_is_automatically_derived == hash_is_automatically_derived {
	207	return;
	208	}
	209
	210	let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
	211
	212	// Only care about `impl PartialEq<Foo> for Foo`
	213	// For `impl PartialEq<B> for A, input_types is [A, B]
	214	if trait_ref.substs.type_at(1) == ty {
	215	let mess = if peq_is_automatically_derived {
	216	"you are implementing `Hash` explicitly but have derived `PartialEq`"
	217	} else {
	218	"you are deriving `Hash` but have implemented `PartialEq` explicitly"
	219	};
	220
	221	span_lint_and_then(
	222	cx,
	223	DERIVE_HASH_XOR_EQ,
	224	span,
	225	mess,
	226	\|diag\| {
	227	if let Some(local_def_id) = impl_id.as_local() {
	228	let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
	229	diag.span_note(
	230	cx.tcx.hir().span(hir_id),
	231	"`PartialEq` implemented here"
	232	);
	233	}
	234	}
	235	);
	236	}
	237	});
	238	}
	239	}
	240	}
	241
	242	/// Implementation of the `DERIVE_ORD_XOR_PARTIAL_ORD` lint.
	243	fn check_ord_partial_ord<'tcx>(
	244	cx: &LateContext<'tcx>,
	245	span: Span,
	246	trait_ref: &TraitRef<'_>,
	247	ty: Ty<'tcx>,
	248	ord_is_automatically_derived: bool,
	249	) {
	250	if_chain! {
ee023bcb	251	if let Some(ord_trait_def_id) = cx.tcx.get_diagnostic_item(sym::Ord);
f20569fa XL	252	if let Some(partial_ord_trait_def_id) = cx.tcx.lang_items().partial_ord_trait();
	253	if let Some(def_id) = &trait_ref.trait_def_id();
	254	if *def_id == ord_trait_def_id;
	255	then {
	256	// Look for the PartialOrd implementations for `ty`
	257	cx.tcx.for_each_relevant_impl(partial_ord_trait_def_id, ty, \|impl_id\| {
cdc7bbd5	258	let partial_ord_is_automatically_derived = is_automatically_derived(cx.tcx.get_attrs(impl_id));
f20569fa XL	259
	260	if partial_ord_is_automatically_derived == ord_is_automatically_derived {
	261	return;
	262	}
	263
	264	let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
	265
	266	// Only care about `impl PartialOrd<Foo> for Foo`
	267	// For `impl PartialOrd<B> for A, input_types is [A, B]
	268	if trait_ref.substs.type_at(1) == ty {
	269	let mess = if partial_ord_is_automatically_derived {
	270	"you are implementing `Ord` explicitly but have derived `PartialOrd`"
	271	} else {
	272	"you are deriving `Ord` but have implemented `PartialOrd` explicitly"
	273	};
	274
	275	span_lint_and_then(
	276	cx,
	277	DERIVE_ORD_XOR_PARTIAL_ORD,
	278	span,
	279	mess,
	280	\|diag\| {
	281	if let Some(local_def_id) = impl_id.as_local() {
	282	let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
	283	diag.span_note(
	284	cx.tcx.hir().span(hir_id),
	285	"`PartialOrd` implemented here"
	286	);
	287	}
	288	}
	289	);
	290	}
	291	});
	292	}
	293	}
	294	}
	295
	296	/// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint.
	297	fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &TraitRef<'_>, ty: Ty<'tcx>) {
cdc7bbd5 XL	298	let clone_id = match cx.tcx.lang_items().clone_trait() {
	299	Some(id) if trait_ref.trait_def_id() == Some(id) => id,
	300	_ => return,
	301	};
	302	let copy_id = match cx.tcx.lang_items().copy_trait() {
	303	Some(id) => id,
	304	None => return,
	305	};
	306	let (ty_adt, ty_subs) = match *ty.kind() {
	307	// Unions can't derive clone.
	308	ty::Adt(adt, subs) if !adt.is_union() => (adt, subs),
	309	_ => return,
	310	};
	311	// If the current self type doesn't implement Copy (due to generic constraints), search to see if
	312	// there's a Copy impl for any instance of the adt.
	313	if !is_copy(cx, ty) {
	314	if ty_subs.non_erasable_generics().next().is_some() {
17df50a5 XL	315	let has_copy_impl = cx.tcx.all_local_trait_impls(()).get(&copy_id).map_or(false, \|impls\| {
	316	impls
	317	.iter()
ee023bcb	318	.any(\|&id\| matches!(cx.tcx.type_of(id).kind(), ty::Adt(adt, _) if ty_adt.did() == adt.did()))
17df50a5	319	});
cdc7bbd5 XL	320	if !has_copy_impl {
	321	return;
	322	}
	323	} else {
f20569fa XL	324	return;
f20569fa XL	325	}
f20569fa	326	}
cdc7bbd5 XL	327	// Derive constrains all generic types to requiring Clone. Check if any type is not constrained for
	328	// this impl.
	329	if ty_subs.types().any(\|ty\| !implements_trait(cx, ty, clone_id, &[])) {
	330	return;
	331	}
	332
	333	span_lint_and_note(
	334	cx,
	335	EXPL_IMPL_CLONE_ON_COPY,
	336	item.span,
	337	"you are implementing `Clone` explicitly on a `Copy` type",
	338	Some(item.span),
	339	"consider deriving `Clone` or removing `Copy`",
	340	);
f20569fa XL	341	}
	342
	343	/// Implementation of the `UNSAFE_DERIVE_DESERIALIZE` lint.
	344	fn check_unsafe_derive_deserialize<'tcx>(
	345	cx: &LateContext<'tcx>,
	346	item: &Item<'_>,
	347	trait_ref: &TraitRef<'_>,
	348	ty: Ty<'tcx>,
	349	) {
f20569fa XL	350	fn has_unsafe<'tcx>(cx: &LateContext<'tcx>, item: &'tcx Item<'_>) -> bool {
	351	let mut visitor = UnsafeVisitor { cx, has_unsafe: false };
	352	walk_item(&mut visitor, item);
	353	visitor.has_unsafe
	354	}
	355
	356	if_chain! {
	357	if let Some(trait_def_id) = trait_ref.trait_def_id();
	358	if match_def_path(cx, trait_def_id, &paths::SERDE_DESERIALIZE);
	359	if let ty::Adt(def, _) = ty.kind();
ee023bcb	360	if let Some(local_def_id) = def.did().as_local();
f20569fa	361	let adt_hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
136023e0	362	if !is_lint_allowed(cx, UNSAFE_DERIVE_DESERIALIZE, adt_hir_id);
ee023bcb	363	if cx.tcx.inherent_impls(def.did())
f20569fa	364	.iter()
a2a8927a	365	.map(\|imp_did\| cx.tcx.hir().expect_item(imp_did.expect_local()))
f20569fa XL	366	.any(\|imp\| has_unsafe(cx, imp));
	367	then {
	368	span_lint_and_help(
	369	cx,
	370	UNSAFE_DERIVE_DESERIALIZE,
	371	item.span,
	372	"you are deriving `serde::Deserialize` on a type that has methods using `unsafe`",
	373	None,
	374	"consider implementing `serde::Deserialize` manually. See https://serde.rs/impl-deserialize.html"
	375	);
	376	}
	377	}
	378	}
	379
	380	struct UnsafeVisitor<'a, 'tcx> {
	381	cx: &'a LateContext<'tcx>,
	382	has_unsafe: bool,
	383	}
	384
	385	impl<'tcx> Visitor<'tcx> for UnsafeVisitor<'_, 'tcx> {
5099ac24	386	type NestedFilter = nested_filter::All;
f20569fa XL	387
	388	fn visit_fn(&mut self, kind: FnKind<'tcx>, decl: &'tcx FnDecl<'_>, body_id: BodyId, span: Span, id: HirId) {
	389	if self.has_unsafe {
	390	return;
	391	}
	392
	393	if_chain! {
	394	if let Some(header) = kind.header();
c295e0f8	395	if header.unsafety == Unsafety::Unsafe;
f20569fa XL	396	then {
	397	self.has_unsafe = true;
	398	}
	399	}
	400
	401	walk_fn(self, kind, decl, body_id, span, id);
	402	}
	403
	404	fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
	405	if self.has_unsafe {
	406	return;
	407	}
	408
	409	if let ExprKind::Block(block, _) = expr.kind {
c295e0f8	410	if block.rules == BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) {
136023e0	411	self.has_unsafe = true;
f20569fa XL	412	}
	413	}
	414
	415	walk_expr(self, expr);
	416	}
	417
5099ac24 FG	418	fn nested_visit_map(&mut self) -> Self::Map {
5099ac24 FG	419	self.cx.tcx.hir()
f20569fa XL	420	}
f20569fa XL	421	}