2 implements_trait, in_macro, is_copy, multispan_sugg, snippet, span_lint, span_lint_and_then, SpanlessEq,
4 use rustc_errors::Applicability;
5 use rustc_hir::{BinOp, BinOpKind, BorrowKind, Expr, ExprKind};
6 use rustc_lint::{LateContext, LateLintPass};
7 use rustc_session::{declare_lint_pass, declare_tool_lint};
10 /// **What it does:** Checks for equal operands to comparison, logical and
11 /// bitwise, difference and division binary operators (`==`, `>`, etc., `&&`,
12 /// `||`, `&`, `|`, `^`, `-` and `/`).
14 /// **Why is this bad?** This is usually just a typo or a copy and paste error.
16 /// **Known problems:** False negatives: We had some false positives regarding
17 /// calls (notably [racer](https://github.com/phildawes/racer) had one instance
18 /// of `x.pop() && x.pop()`), so we removed matching any function or method
19 /// calls. We may introduce a whitelist of known pure functions in the future.
24 /// if x + 1 == x + 1 {}
28 "equal operands on both sides of a comparison or bitwise combination (e.g., `x == x`)"
31 declare_clippy_lint! {
32 /// **What it does:** Checks for arguments to `==` which have their address
33 /// taken to satisfy a bound
34 /// and suggests to dereference the other argument instead
36 /// **Why is this bad?** It is more idiomatic to dereference the other argument.
38 /// **Known problems:** None
46 "taking a reference to satisfy the type constraints on `==`"
49 declare_lint_pass!(EqOp => [EQ_OP, OP_REF]);
51 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EqOp {
52 #[allow(clippy::similar_names, clippy::too_many_lines)]
53 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) {
54 if let ExprKind::Binary(op, ref left, ref right) = e.kind {
55 if e.span.from_expansion() {
58 let macro_with_not_op = |expr_kind: &ExprKind<'_>| {
59 if let ExprKind::Unary(_, ref expr) = *expr_kind {
65 if macro_with_not_op(&left.kind) || macro_with_not_op(&right.kind) {
68 if is_valid_operator(op) && SpanlessEq::new(cx).ignore_fn().eq_expr(left, right) {
73 &format!("equal expressions as operands to `{}`", op.node.as_str()),
77 let (trait_id, requires_ref) = match op.node {
78 BinOpKind::Add => (cx.tcx.lang_items().add_trait(), false),
79 BinOpKind::Sub => (cx.tcx.lang_items().sub_trait(), false),
80 BinOpKind::Mul => (cx.tcx.lang_items().mul_trait(), false),
81 BinOpKind::Div => (cx.tcx.lang_items().div_trait(), false),
82 BinOpKind::Rem => (cx.tcx.lang_items().rem_trait(), false),
83 // don't lint short circuiting ops
84 BinOpKind::And | BinOpKind::Or => return,
85 BinOpKind::BitXor => (cx.tcx.lang_items().bitxor_trait(), false),
86 BinOpKind::BitAnd => (cx.tcx.lang_items().bitand_trait(), false),
87 BinOpKind::BitOr => (cx.tcx.lang_items().bitor_trait(), false),
88 BinOpKind::Shl => (cx.tcx.lang_items().shl_trait(), false),
89 BinOpKind::Shr => (cx.tcx.lang_items().shr_trait(), false),
90 BinOpKind::Ne | BinOpKind::Eq => (cx.tcx.lang_items().eq_trait(), true),
91 BinOpKind::Lt | BinOpKind::Le | BinOpKind::Ge | BinOpKind::Gt => {
92 (cx.tcx.lang_items().partial_ord_trait(), true)
95 if let Some(trait_id) = trait_id {
96 #[allow(clippy::match_same_arms)]
97 match (&left.kind, &right.kind) {
98 // do not suggest to dereference literals
99 (&ExprKind::Lit(..), _) | (_, &ExprKind::Lit(..)) => {},
101 (&ExprKind::AddrOf(BorrowKind::Ref, _, ref l), &ExprKind::AddrOf(BorrowKind::Ref, _, ref r)) => {
102 let lty = cx.tables.expr_ty(l);
103 let rty = cx.tables.expr_ty(r);
104 let lcpy = is_copy(cx, lty);
105 let rcpy = is_copy(cx, rty);
106 // either operator autorefs or both args are copyable
107 if (requires_ref || (lcpy && rcpy)) && implements_trait(cx, lty, trait_id, &[rty.into()]) {
112 "needlessly taken reference of both operands",
114 let lsnip = snippet(cx, l.span, "...").to_string();
115 let rsnip = snippet(cx, r.span, "...").to_string();
118 "use the values directly".to_string(),
119 vec![(left.span, lsnip), (right.span, rsnip)],
125 && implements_trait(cx, lty, trait_id, &[cx.tables.expr_ty(right).into()])
131 "needlessly taken reference of left operand",
133 let lsnip = snippet(cx, l.span, "...").to_string();
134 diag.span_suggestion(
136 "use the left value directly",
138 Applicability::MaybeIncorrect, // FIXME #2597
144 && implements_trait(cx, cx.tables.expr_ty(left), trait_id, &[rty.into()])
150 "needlessly taken reference of right operand",
152 let rsnip = snippet(cx, r.span, "...").to_string();
153 diag.span_suggestion(
155 "use the right value directly",
157 Applicability::MaybeIncorrect, // FIXME #2597
164 (&ExprKind::AddrOf(BorrowKind::Ref, _, ref l), _) => {
165 let lty = cx.tables.expr_ty(l);
166 let lcpy = is_copy(cx, lty);
167 if (requires_ref || lcpy)
168 && implements_trait(cx, lty, trait_id, &[cx.tables.expr_ty(right).into()])
174 "needlessly taken reference of left operand",
176 let lsnip = snippet(cx, l.span, "...").to_string();
177 diag.span_suggestion(
179 "use the left value directly",
181 Applicability::MaybeIncorrect, // FIXME #2597
188 (_, &ExprKind::AddrOf(BorrowKind::Ref, _, ref r)) => {
189 let rty = cx.tables.expr_ty(r);
190 let rcpy = is_copy(cx, rty);
191 if (requires_ref || rcpy)
192 && implements_trait(cx, cx.tables.expr_ty(left), trait_id, &[rty.into()])
194 span_lint_and_then(cx, OP_REF, e.span, "taken reference of right operand", |diag| {
195 let rsnip = snippet(cx, r.span, "...").to_string();
196 diag.span_suggestion(
198 "use the right value directly",
200 Applicability::MaybeIncorrect, // FIXME #2597
212 fn is_valid_operator(op: BinOp) -> bool {
226 | BinOpKind::BitOr => true,