424 lines
14 KiB
Rust
424 lines
14 KiB
Rust
use crate::utils::paths;
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use crate::utils::{
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get_trait_def_id, is_allowed, is_automatically_derived, is_copy, match_def_path, match_path, span_lint_and_help,
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span_lint_and_note, span_lint_and_then,
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};
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use if_chain::if_chain;
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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, NestedVisitorMap, Visitor};
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use rustc_hir::{
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BlockCheckMode, BodyId, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, TraitRef, UnsafeSource, Unsafety,
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};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::hir::map::Map;
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use rustc_middle::ty::{self, Ty};
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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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declare_clippy_lint! {
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/// **What it does:** 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?** 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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/// **Known problems:** None.
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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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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:** 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?** 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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/// **Known problems:** None.
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///
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/// **Example:**
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///
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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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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:** Checks for explicit `Clone` implementations for `Copy`
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/// types.
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///
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/// **Why is this bad?** To avoid surprising behaviour, these traits should
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/// agree and the behaviour 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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/// **Known problems:** Bounds of generic types are sometimes wrong: https://github.com/rust-lang/rust/issues/26925
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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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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:** 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?** 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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/// **Known problems:** None.
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///
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/// **Example:**
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///
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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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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_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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]);
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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 = is_automatically_derived(&*item.attrs);
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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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} 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: &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 match_def_path(cx, def_id, &paths::HASH);
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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 = is_automatically_derived(&cx.tcx.get_attrs(impl_id));
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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: &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) = get_trait_def_id(cx, &paths::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 = is_automatically_derived(&cx.tcx.get_attrs(impl_id));
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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: &TraitRef<'_>, ty: Ty<'tcx>) {
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if match_path(&trait_ref.path, &paths::CLONE_TRAIT) {
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if !is_copy(cx, ty) {
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return;
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}
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match *ty.kind() {
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ty::Adt(def, _) if def.is_union() => return,
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// Some types are not Clone by default but could be cloned “by hand” if necessary
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ty::Adt(def, substs) => {
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for variant in &def.variants {
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for field in &variant.fields {
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if let ty::FnDef(..) = field.ty(cx.tcx, substs).kind() {
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return;
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}
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}
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for subst in substs {
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if let ty::subst::GenericArgKind::Type(subst) = subst.unpack() {
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if let ty::Param(_) = subst.kind() {
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return;
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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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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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}
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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: &TraitRef<'_>,
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ty: Ty<'tcx>,
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) {
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fn item_from_def_id<'tcx>(cx: &LateContext<'tcx>, def_id: DefId) -> &'tcx Item<'tcx> {
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let hir_id = cx.tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
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cx.tcx.hir().expect_item(hir_id)
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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_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| item_from_def_id(cx, *imp_did))
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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 Map = Map<'tcx>;
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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 let Unsafety::Unsafe = header.unsafety;
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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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match block.rules {
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BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided)
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| BlockCheckMode::PushUnsafeBlock(UnsafeSource::UserProvided)
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| BlockCheckMode::PopUnsafeBlock(UnsafeSource::UserProvided) => {
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self.has_unsafe = true;
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},
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_ => {},
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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) -> NestedVisitorMap<Self::Map> {
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NestedVisitorMap::All(self.cx.tcx.hir())
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}
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}
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