mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-22 19:13:29 +00:00
528 lines
18 KiB
Rust
528 lines
18 KiB
Rust
use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note, span_lint_and_sugg, span_lint_and_then};
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use clippy_utils::paths;
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use clippy_utils::ty::{implements_trait, implements_trait_with_env, is_copy};
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use clippy_utils::{is_lint_allowed, match_def_path};
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir::def_id::DefId;
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use rustc_hir::intravisit::{walk_expr, walk_fn, walk_item, FnKind, Visitor};
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use rustc_hir::{
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self as hir, BlockCheckMode, BodyId, Constness, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, UnsafeSource,
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Unsafety,
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};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::hir::nested_filter;
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use rustc_middle::traits::Reveal;
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use rustc_middle::ty::{
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self, Binder, BoundConstness, GenericParamDefKind, ImplPolarity, ParamEnv, PredicateKind, TraitPredicate, TraitRef,
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Ty, TyCtxt, Visibility,
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};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::source_map::Span;
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use rustc_span::sym;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for deriving `Hash` but implementing `PartialEq`
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/// explicitly or vice versa.
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///
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/// ### Why is this bad?
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/// The implementation of these traits must agree (for
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/// example for use with `HashMap`) so it’s probably a bad idea to use a
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/// default-generated `Hash` implementation with an explicitly defined
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/// `PartialEq`. In particular, the following must hold for any type:
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///
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/// ```text
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/// k1 == k2 ⇒ hash(k1) == hash(k2)
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/// ```
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///
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/// ### Example
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/// ```ignore
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/// #[derive(Hash)]
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/// struct Foo;
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///
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/// impl PartialEq for Foo {
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/// ...
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/// }
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub DERIVE_HASH_XOR_EQ,
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correctness,
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"deriving `Hash` but implementing `PartialEq` explicitly"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for deriving `Ord` but implementing `PartialOrd`
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/// explicitly or vice versa.
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///
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/// ### Why is this bad?
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/// The implementation of these traits must agree (for
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/// example for use with `sort`) so it’s probably a bad idea to use a
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/// default-generated `Ord` implementation with an explicitly defined
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/// `PartialOrd`. In particular, the following must hold for any type
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/// implementing `Ord`:
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///
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/// ```text
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/// k1.cmp(&k2) == k1.partial_cmp(&k2).unwrap()
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/// ```
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///
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/// ### Example
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/// ```rust,ignore
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/// #[derive(Ord, PartialEq, Eq)]
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/// struct Foo;
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///
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/// impl PartialOrd for Foo {
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/// ...
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/// }
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/// ```
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/// Use instead:
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/// ```rust,ignore
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/// #[derive(PartialEq, Eq)]
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/// struct Foo;
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///
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/// impl PartialOrd for Foo {
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/// fn partial_cmp(&self, other: &Foo) -> Option<Ordering> {
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/// Some(self.cmp(other))
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/// }
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/// }
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///
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/// impl Ord for Foo {
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/// ...
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/// }
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/// ```
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/// or, if you don't need a custom ordering:
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/// ```rust,ignore
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/// #[derive(Ord, PartialOrd, PartialEq, Eq)]
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/// struct Foo;
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/// ```
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#[clippy::version = "1.47.0"]
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pub DERIVE_ORD_XOR_PARTIAL_ORD,
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correctness,
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"deriving `Ord` but implementing `PartialOrd` explicitly"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for explicit `Clone` implementations for `Copy`
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/// types.
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///
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/// ### Why is this bad?
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/// To avoid surprising behavior, these traits should
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/// agree and the behavior of `Copy` cannot be overridden. In almost all
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/// situations a `Copy` type should have a `Clone` implementation that does
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/// nothing more than copy the object, which is what `#[derive(Copy, Clone)]`
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/// gets you.
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///
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/// ### Example
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/// ```rust,ignore
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/// #[derive(Copy)]
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/// struct Foo;
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///
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/// impl Clone for Foo {
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/// // ..
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/// }
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub EXPL_IMPL_CLONE_ON_COPY,
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pedantic,
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"implementing `Clone` explicitly on `Copy` types"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for deriving `serde::Deserialize` on a type that
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/// has methods using `unsafe`.
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///
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/// ### Why is this bad?
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/// Deriving `serde::Deserialize` will create a constructor
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/// that may violate invariants hold by another constructor.
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///
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/// ### Example
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/// ```rust,ignore
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/// use serde::Deserialize;
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///
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/// #[derive(Deserialize)]
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/// pub struct Foo {
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/// // ..
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/// }
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///
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/// impl Foo {
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/// pub fn new() -> Self {
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/// // setup here ..
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/// }
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///
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/// pub unsafe fn parts() -> (&str, &str) {
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/// // assumes invariants hold
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/// }
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/// }
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/// ```
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#[clippy::version = "1.45.0"]
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pub UNSAFE_DERIVE_DESERIALIZE,
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pedantic,
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"deriving `serde::Deserialize` on a type that has methods using `unsafe`"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for types that derive `PartialEq` and could implement `Eq`.
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///
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/// ### Why is this bad?
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/// If a type `T` derives `PartialEq` and all of its members implement `Eq`,
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/// then `T` can always implement `Eq`. Implementing `Eq` allows `T` to be used
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/// in APIs that require `Eq` types. It also allows structs containing `T` to derive
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/// `Eq` themselves.
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///
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/// ### Example
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/// ```rust
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/// #[derive(PartialEq)]
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/// struct Foo {
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/// i_am_eq: i32,
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/// i_am_eq_too: Vec<String>,
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/// }
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/// ```
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/// Use instead:
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/// ```rust
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/// #[derive(PartialEq, Eq)]
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/// struct Foo {
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/// i_am_eq: i32,
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/// i_am_eq_too: Vec<String>,
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/// }
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/// ```
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#[clippy::version = "1.63.0"]
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pub DERIVE_PARTIAL_EQ_WITHOUT_EQ,
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style,
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"deriving `PartialEq` on a type that can implement `Eq`, without implementing `Eq`"
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}
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declare_lint_pass!(Derive => [
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EXPL_IMPL_CLONE_ON_COPY,
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DERIVE_HASH_XOR_EQ,
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DERIVE_ORD_XOR_PARTIAL_ORD,
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UNSAFE_DERIVE_DESERIALIZE,
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DERIVE_PARTIAL_EQ_WITHOUT_EQ
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]);
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impl<'tcx> LateLintPass<'tcx> for Derive {
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fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
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if let ItemKind::Impl(Impl {
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of_trait: Some(ref trait_ref),
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..
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}) = item.kind
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{
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let ty = cx.tcx.type_of(item.def_id);
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let is_automatically_derived = cx.tcx.has_attr(item.def_id.to_def_id(), sym::automatically_derived);
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check_hash_peq(cx, item.span, trait_ref, ty, is_automatically_derived);
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check_ord_partial_ord(cx, item.span, trait_ref, ty, is_automatically_derived);
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if is_automatically_derived {
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check_unsafe_derive_deserialize(cx, item, trait_ref, ty);
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check_partial_eq_without_eq(cx, item.span, trait_ref, ty);
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} else {
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check_copy_clone(cx, item, trait_ref, ty);
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}
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}
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}
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}
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/// Implementation of the `DERIVE_HASH_XOR_EQ` lint.
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fn check_hash_peq<'tcx>(
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cx: &LateContext<'tcx>,
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span: Span,
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trait_ref: &hir::TraitRef<'_>,
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ty: Ty<'tcx>,
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hash_is_automatically_derived: bool,
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) {
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if_chain! {
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if let Some(peq_trait_def_id) = cx.tcx.lang_items().eq_trait();
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if let Some(def_id) = trait_ref.trait_def_id();
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if cx.tcx.is_diagnostic_item(sym::Hash, def_id);
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then {
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// Look for the PartialEq implementations for `ty`
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cx.tcx.for_each_relevant_impl(peq_trait_def_id, ty, |impl_id| {
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let peq_is_automatically_derived = cx.tcx.has_attr(impl_id, sym::automatically_derived);
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if peq_is_automatically_derived == hash_is_automatically_derived {
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return;
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}
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let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
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// Only care about `impl PartialEq<Foo> for Foo`
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// For `impl PartialEq<B> for A, input_types is [A, B]
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if trait_ref.substs.type_at(1) == ty {
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let mess = if peq_is_automatically_derived {
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"you are implementing `Hash` explicitly but have derived `PartialEq`"
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} else {
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"you are deriving `Hash` but have implemented `PartialEq` explicitly"
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};
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span_lint_and_then(
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cx,
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DERIVE_HASH_XOR_EQ,
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span,
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mess,
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|diag| {
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if let Some(local_def_id) = impl_id.as_local() {
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let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
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diag.span_note(
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cx.tcx.hir().span(hir_id),
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"`PartialEq` implemented here"
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);
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}
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}
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);
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}
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});
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}
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}
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}
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/// Implementation of the `DERIVE_ORD_XOR_PARTIAL_ORD` lint.
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fn check_ord_partial_ord<'tcx>(
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cx: &LateContext<'tcx>,
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span: Span,
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trait_ref: &hir::TraitRef<'_>,
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ty: Ty<'tcx>,
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ord_is_automatically_derived: bool,
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) {
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if_chain! {
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if let Some(ord_trait_def_id) = cx.tcx.get_diagnostic_item(sym::Ord);
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if let Some(partial_ord_trait_def_id) = cx.tcx.lang_items().partial_ord_trait();
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if let Some(def_id) = &trait_ref.trait_def_id();
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if *def_id == ord_trait_def_id;
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then {
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// Look for the PartialOrd implementations for `ty`
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cx.tcx.for_each_relevant_impl(partial_ord_trait_def_id, ty, |impl_id| {
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let partial_ord_is_automatically_derived = cx.tcx.has_attr(impl_id, sym::automatically_derived);
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if partial_ord_is_automatically_derived == ord_is_automatically_derived {
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return;
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}
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let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
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// Only care about `impl PartialOrd<Foo> for Foo`
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// For `impl PartialOrd<B> for A, input_types is [A, B]
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if trait_ref.substs.type_at(1) == ty {
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let mess = if partial_ord_is_automatically_derived {
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"you are implementing `Ord` explicitly but have derived `PartialOrd`"
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} else {
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"you are deriving `Ord` but have implemented `PartialOrd` explicitly"
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};
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span_lint_and_then(
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cx,
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DERIVE_ORD_XOR_PARTIAL_ORD,
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span,
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mess,
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|diag| {
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if let Some(local_def_id) = impl_id.as_local() {
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let hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
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diag.span_note(
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cx.tcx.hir().span(hir_id),
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"`PartialOrd` implemented here"
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);
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}
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}
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);
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}
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});
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}
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}
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}
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/// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint.
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fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &hir::TraitRef<'_>, ty: Ty<'tcx>) {
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let clone_id = match cx.tcx.lang_items().clone_trait() {
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Some(id) if trait_ref.trait_def_id() == Some(id) => id,
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_ => return,
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};
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let copy_id = match cx.tcx.lang_items().copy_trait() {
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Some(id) => id,
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None => return,
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};
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let (ty_adt, ty_subs) = match *ty.kind() {
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// Unions can't derive clone.
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ty::Adt(adt, subs) if !adt.is_union() => (adt, subs),
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_ => return,
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};
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// If the current self type doesn't implement Copy (due to generic constraints), search to see if
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// there's a Copy impl for any instance of the adt.
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if !is_copy(cx, ty) {
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if ty_subs.non_erasable_generics().next().is_some() {
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let has_copy_impl = cx.tcx.all_local_trait_impls(()).get(©_id).map_or(false, |impls| {
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impls
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.iter()
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.any(|&id| matches!(cx.tcx.type_of(id).kind(), ty::Adt(adt, _) if ty_adt.did() == adt.did()))
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});
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if !has_copy_impl {
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return;
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}
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} else {
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return;
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}
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}
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// Derive constrains all generic types to requiring Clone. Check if any type is not constrained for
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// this impl.
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if ty_subs.types().any(|ty| !implements_trait(cx, ty, clone_id, &[])) {
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return;
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}
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span_lint_and_note(
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cx,
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EXPL_IMPL_CLONE_ON_COPY,
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item.span,
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"you are implementing `Clone` explicitly on a `Copy` type",
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Some(item.span),
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"consider deriving `Clone` or removing `Copy`",
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);
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}
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/// Implementation of the `UNSAFE_DERIVE_DESERIALIZE` lint.
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fn check_unsafe_derive_deserialize<'tcx>(
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cx: &LateContext<'tcx>,
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item: &Item<'_>,
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trait_ref: &hir::TraitRef<'_>,
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ty: Ty<'tcx>,
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) {
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fn has_unsafe<'tcx>(cx: &LateContext<'tcx>, item: &'tcx Item<'_>) -> bool {
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let mut visitor = UnsafeVisitor { cx, has_unsafe: false };
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walk_item(&mut visitor, item);
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visitor.has_unsafe
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}
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if_chain! {
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if let Some(trait_def_id) = trait_ref.trait_def_id();
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if match_def_path(cx, trait_def_id, &paths::SERDE_DESERIALIZE);
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if let ty::Adt(def, _) = ty.kind();
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if let Some(local_def_id) = def.did().as_local();
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let adt_hir_id = cx.tcx.hir().local_def_id_to_hir_id(local_def_id);
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if !is_lint_allowed(cx, UNSAFE_DERIVE_DESERIALIZE, adt_hir_id);
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if cx.tcx.inherent_impls(def.did())
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.iter()
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.map(|imp_did| cx.tcx.hir().expect_item(imp_did.expect_local()))
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.any(|imp| has_unsafe(cx, imp));
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then {
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span_lint_and_help(
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cx,
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UNSAFE_DERIVE_DESERIALIZE,
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item.span,
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"you are deriving `serde::Deserialize` on a type that has methods using `unsafe`",
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None,
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"consider implementing `serde::Deserialize` manually. See https://serde.rs/impl-deserialize.html"
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);
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}
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}
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}
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struct UnsafeVisitor<'a, 'tcx> {
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cx: &'a LateContext<'tcx>,
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has_unsafe: bool,
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}
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impl<'tcx> Visitor<'tcx> for UnsafeVisitor<'_, 'tcx> {
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type NestedFilter = nested_filter::All;
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fn visit_fn(&mut self, kind: FnKind<'tcx>, decl: &'tcx FnDecl<'_>, body_id: BodyId, span: Span, id: HirId) {
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if self.has_unsafe {
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return;
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}
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if_chain! {
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if let Some(header) = kind.header();
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if header.unsafety == Unsafety::Unsafe;
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then {
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self.has_unsafe = true;
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}
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}
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walk_fn(self, kind, decl, body_id, span, id);
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}
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fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
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if self.has_unsafe {
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return;
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}
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if let ExprKind::Block(block, _) = expr.kind {
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if block.rules == BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) {
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self.has_unsafe = true;
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}
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}
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walk_expr(self, expr);
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}
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fn nested_visit_map(&mut self) -> Self::Map {
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self.cx.tcx.hir()
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}
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}
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/// Implementation of the `DERIVE_PARTIAL_EQ_WITHOUT_EQ` lint.
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fn check_partial_eq_without_eq<'tcx>(cx: &LateContext<'tcx>, span: Span, trait_ref: &hir::TraitRef<'_>, ty: Ty<'tcx>) {
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if_chain! {
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if let ty::Adt(adt, substs) = ty.kind();
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if cx.tcx.visibility(adt.did()) == Visibility::Public;
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if let Some(eq_trait_def_id) = cx.tcx.get_diagnostic_item(sym::Eq);
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if let Some(def_id) = trait_ref.trait_def_id();
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if cx.tcx.is_diagnostic_item(sym::PartialEq, def_id);
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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([tcx.mk_param_from_def(param)].into_iter())),
|
||
constness: BoundConstness::NotConst,
|
||
polarity: ImplPolarity::Positive,
|
||
})))
|
||
}),
|
||
)),
|
||
Reveal::UserFacing,
|
||
Constness::NotConst,
|
||
)
|
||
}
|