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fix op_ref false positive

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This commit is contained in:
Elliot Bobrow 2022-01-16 09:17:22 -08:00
parent 88f5be2041
commit fb5f51d3eb
3 changed files with 123 additions and 3 deletions
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69
clippy_lints/src/eq_op.rs
View file

@ -1,12 +1,16 @@
use clippy_utils::diagnostics::{multispan_sugg, span_lint, span_lint_and_then};
use clippy_utils::get_enclosing_block;
use clippy_utils::macros::{find_assert_eq_args, first_node_macro_backtrace};
use clippy_utils::source::snippet;
use clippy_utils::ty::{implements_trait, is_copy};
use clippy_utils::{ast_utils::is_useless_with_eq_exprs, eq_expr_value, is_in_test_function};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind};
use rustc_hir::{
def::Res, def_id::DefId, BinOpKind, BorrowKind, Expr, ExprKind, GenericArg, ItemKind, QPath, Ty, TyKind,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::{self, TyS};
use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
@ -146,6 +150,13 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
let rty = cx.typeck_results().expr_ty(r);
let lcpy = is_copy(cx, lty);
let rcpy = is_copy(cx, rty);
if let Some((self_ty, other_ty)) = in_impl(cx, e, trait_id) {
if (are_equal(cx, rty, self_ty) && are_equal(cx, lty, other_ty))
|| (are_equal(cx, rty, other_ty) && are_equal(cx, lty, self_ty))
{
return; // Don't lint
}
}
// either operator autorefs or both args are copyable
if (requires_ref || (lcpy && rcpy)) && implements_trait(cx, lty, trait_id, &[rty.into()]) {
span_lint_and_then(
@ -206,6 +217,14 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
// &foo == bar
(&ExprKind::AddrOf(BorrowKind::Ref, _, l), _) => {
let lty = cx.typeck_results().expr_ty(l);
if let Some((self_ty, other_ty)) = in_impl(cx, e, trait_id) {
let rty = cx.typeck_results().expr_ty(right);
if (are_equal(cx, rty, self_ty) && are_equal(cx, lty, other_ty))
|| (are_equal(cx, rty, other_ty) && are_equal(cx, lty, self_ty))
{
return; // Don't lint
}
}
let lcpy = is_copy(cx, lty);
if (requires_ref || lcpy)
&& implements_trait(cx, lty, trait_id, &[cx.typeck_results().expr_ty(right).into()])
@ -230,6 +249,14 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
// foo == &bar
(_, &ExprKind::AddrOf(BorrowKind::Ref, _, r)) => {
let rty = cx.typeck_results().expr_ty(r);
if let Some((self_ty, other_ty)) = in_impl(cx, e, trait_id) {
let lty = cx.typeck_results().expr_ty(left);
if (are_equal(cx, rty, self_ty) && are_equal(cx, lty, other_ty))
|| (are_equal(cx, rty, other_ty) && are_equal(cx, lty, self_ty))
{
return; // Don't lint
}
}
let rcpy = is_copy(cx, rty);
if (requires_ref || rcpy)
&& implements_trait(cx, cx.typeck_results().expr_ty(left), trait_id, &[rty.into()])
@ -251,3 +278,43 @@ impl<'tcx> LateLintPass<'tcx> for EqOp {
}
}
}
fn in_impl<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>, bin_op: DefId) -> Option<(&'tcx Ty<'tcx>, &'tcx Ty<'tcx>)> {
if_chain! {
if let Some(block) = get_enclosing_block(cx, e.hir_id);
if let Some(impl_def_id) = cx.tcx.impl_of_method(block.hir_id.owner.to_def_id());
let item = cx.tcx.hir().expect_item(impl_def_id.expect_local());
if let ItemKind::Impl(item) = &item.kind;
if let Some(of_trait) = &item.of_trait;
if let Some(seg) = of_trait.path.segments.last();
if let Some(Res::Def(_, trait_id)) = seg.res;
if trait_id == bin_op;
if let Some(generic_args) = seg.args;
if let Some(GenericArg::Type(other_ty)) = generic_args.args.last();
then {
Some((item.self_ty, other_ty))
}
else {
None
}
}
}
fn are_equal<'tcx>(cx: &LateContext<'tcx>, middle_ty: &TyS<'_>, hir_ty: &Ty<'_>) -> bool {
if_chain! {
if let ty::Adt(adt_def, _) = middle_ty.kind();
if let Some(local_did) = adt_def.did.as_local();
let item = cx.tcx.hir().expect_item(local_did);
let middle_ty_id = item.def_id.to_def_id();
if let TyKind::Path(QPath::Resolved(_, path)) = hir_ty.kind;
if let Res::Def(_, hir_ty_id) = path.res;
then {
hir_ty_id == middle_ty_id
}
else {
false
}
}
}

39
tests/ui/op_ref.rs
View file

@ -1,7 +1,7 @@
#![allow(unused_variables, clippy::blacklisted_name)]
#![warn(clippy::op_ref)]
use std::collections::HashSet;
use std::ops::BitAnd;
use std::ops::{BitAnd, Mul};
fn main() {
let tracked_fds: HashSet<i32> = HashSet::new();
@ -55,3 +55,40 @@ fn main() {
let y = Y(2);
let z = x & &y;
}
#[derive(Clone, Copy)]
struct A(i32);
#[derive(Clone, Copy)]
struct B(i32);
impl Mul<&A> for B {
type Output = i32;
fn mul(self, rhs: &A) -> Self::Output {
self.0 * rhs.0
}
}
impl Mul<A> for B {
type Output = i32;
fn mul(self, rhs: A) -> Self::Output {
// Should not lint because removing the reference would lead to unconditional recursion
self * &rhs
}
}
impl Mul<&A> for A {
type Output = i32;
fn mul(self, rhs: &A) -> Self::Output {
self.0 * rhs.0
}
}
impl Mul<A> for A {
type Output = i32;
fn mul(self, rhs: A) -> Self::Output {
let one = B(1);
let two = 2;
let three = 3;
let _ = one * &self;
let _ = two + &three;
// Removing the reference would lead to unconditional recursion
self * &rhs
}
}

18
tests/ui/op_ref.stderr
View file

@ -18,5 +18,21 @@ LL | let z = x & &y;
| |
| help: use the right value directly: `y`
error: aborting due to 2 previous errors
error: taken reference of right operand
--> $DIR/op_ref.rs:89:17
|
LL | let _ = one * &self;
| ^^^^^^-----
| |
| help: use the right value directly: `self`
error: taken reference of right operand
--> $DIR/op_ref.rs:90:17
|
LL | let _ = two + &three;
| ^^^^^^------
| |
| help: use the right value directly: `three`
error: aborting due to 4 previous errors