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
50 "taking a reference to satisfy the type constraints on `==`"
53 declare_lint_pass!(EqOp => [EQ_OP, OP_REF]);
55 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EqOp {
56 #[allow(clippy::similar_names, clippy::too_many_lines)]
57 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) {
58 if let ExprKind::Binary(op, ref left, ref right) = e.kind {
59 if e.span.from_expansion() {
62 let macro_with_not_op = |expr_kind: &ExprKind<'_>| {
63 if let ExprKind::Unary(_, ref expr) = *expr_kind {
69 if macro_with_not_op(&left.kind) || macro_with_not_op(&right.kind) {
72 if is_valid_operator(op) && SpanlessEq::new(cx).ignore_fn().eq_expr(left, right) {
77 &format!("equal expressions as operands to `{}`", op.node.as_str()),
81 let (trait_id, requires_ref) = match op.node {
82 BinOpKind::Add => (cx.tcx.lang_items().add_trait(), false),
83 BinOpKind::Sub => (cx.tcx.lang_items().sub_trait(), false),
84 BinOpKind::Mul => (cx.tcx.lang_items().mul_trait(), false),
85 BinOpKind::Div => (cx.tcx.lang_items().div_trait(), false),
86 BinOpKind::Rem => (cx.tcx.lang_items().rem_trait(), false),
87 // don't lint short circuiting ops
88 BinOpKind::And | BinOpKind::Or => return,
89 BinOpKind::BitXor => (cx.tcx.lang_items().bitxor_trait(), false),
90 BinOpKind::BitAnd => (cx.tcx.lang_items().bitand_trait(), false),
91 BinOpKind::BitOr => (cx.tcx.lang_items().bitor_trait(), false),
92 BinOpKind::Shl => (cx.tcx.lang_items().shl_trait(), false),
93 BinOpKind::Shr => (cx.tcx.lang_items().shr_trait(), false),
94 BinOpKind::Ne | BinOpKind::Eq => (cx.tcx.lang_items().eq_trait(), true),
95 BinOpKind::Lt | BinOpKind::Le | BinOpKind::Ge | BinOpKind::Gt => {
96 (cx.tcx.lang_items().partial_ord_trait(), true)
99 if let Some(trait_id) = trait_id {
100 #[allow(clippy::match_same_arms)]
101 match (&left.kind, &right.kind) {
102 // do not suggest to dereference literals
103 (&ExprKind::Lit(..), _) | (_, &ExprKind::Lit(..)) => {},
105 (&ExprKind::AddrOf(BorrowKind::Ref, _, ref l), &ExprKind::AddrOf(BorrowKind::Ref, _, ref r)) => {
106 let lty = cx.tables.expr_ty(l);
107 let rty = cx.tables.expr_ty(r);
108 let lcpy = is_copy(cx, lty);
109 let rcpy = is_copy(cx, rty);
110 // either operator autorefs or both args are copyable
111 if (requires_ref || (lcpy && rcpy)) && implements_trait(cx, lty, trait_id, &[rty.into()]) {
116 "needlessly taken reference of both operands",
118 let lsnip = snippet(cx, l.span, "...").to_string();
119 let rsnip = snippet(cx, r.span, "...").to_string();
122 "use the values directly",
123 vec![(left.span, lsnip), (right.span, rsnip)],
129 && implements_trait(cx, lty, trait_id, &[cx.tables.expr_ty(right).into()])
135 "needlessly taken reference of left operand",
137 let lsnip = snippet(cx, l.span, "...").to_string();
138 diag.span_suggestion(
140 "use the left value directly",
142 Applicability::MaybeIncorrect, // FIXME #2597
148 && implements_trait(cx, cx.tables.expr_ty(left), trait_id, &[rty.into()])
154 "needlessly taken reference of right operand",
156 let rsnip = snippet(cx, r.span, "...").to_string();
157 diag.span_suggestion(
159 "use the right value directly",
161 Applicability::MaybeIncorrect, // FIXME #2597
168 (&ExprKind::AddrOf(BorrowKind::Ref, _, ref l), _) => {
169 let lty = cx.tables.expr_ty(l);
170 let lcpy = is_copy(cx, lty);
171 if (requires_ref || lcpy)
172 && implements_trait(cx, lty, trait_id, &[cx.tables.expr_ty(right).into()])
178 "needlessly taken reference of left operand",
180 let lsnip = snippet(cx, l.span, "...").to_string();
181 diag.span_suggestion(
183 "use the left value directly",
185 Applicability::MaybeIncorrect, // FIXME #2597
192 (_, &ExprKind::AddrOf(BorrowKind::Ref, _, ref r)) => {
193 let rty = cx.tables.expr_ty(r);
194 let rcpy = is_copy(cx, rty);
195 if (requires_ref || rcpy)
196 && implements_trait(cx, cx.tables.expr_ty(left), trait_id, &[rty.into()])
198 span_lint_and_then(cx, OP_REF, e.span, "taken reference of right operand", |diag| {
199 let rsnip = snippet(cx, r.span, "...").to_string();
200 diag.span_suggestion(
202 "use the right value directly",
204 Applicability::MaybeIncorrect, // FIXME #2597
216 fn is_valid_operator(op: BinOp) -> bool {
230 | BinOpKind::BitOr => true,