1 use clippy_utils::diagnostics::{multispan_sugg, span_lint, span_lint_and_then};
2 use clippy_utils::source::snippet;
3 use clippy_utils::ty::{implements_trait, is_copy};
4 use clippy_utils::{ast_utils::is_useless_with_eq_exprs, eq_expr_value, higher, in_macro, is_expn_of};
5 use if_chain::if_chain;
6 use rustc_errors::Applicability;
7 use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, StmtKind};
8 use rustc_lint::{LateContext, LateLintPass};
9 use rustc_session::{declare_lint_pass, declare_tool_lint};
11 declare_clippy_lint! {
12 /// **What it does:** Checks for equal operands to comparison, logical and
13 /// bitwise, difference and division binary operators (`==`, `>`, etc., `&&`,
14 /// `||`, `&`, `|`, `^`, `-` and `/`).
16 /// **Why is this bad?** This is usually just a typo or a copy and paste error.
18 /// **Known problems:** False negatives: We had some false positives regarding
19 /// calls (notably [racer](https://github.com/phildawes/racer) had one instance
20 /// of `x.pop() && x.pop()`), so we removed matching any function or method
21 /// calls. We may introduce a list of known pure functions in the future.
26 /// if x + 1 == x + 1 {}
36 "equal operands on both sides of a comparison or bitwise combination (e.g., `x == x`)"
39 declare_clippy_lint! {
40 /// **What it does:** Checks for arguments to `==` which have their address
41 /// taken to satisfy a bound
42 /// and suggests to dereference the other argument instead
44 /// **Why is this bad?** It is more idiomatic to dereference the other argument.
46 /// **Known problems:** None
58 "taking a reference to satisfy the type constraints on `==`"
61 declare_lint_pass!(EqOp => [EQ_OP, OP_REF]);
63 const ASSERT_MACRO_NAMES: [&str; 4] = ["assert_eq", "assert_ne", "debug_assert_eq", "debug_assert_ne"];
65 impl<'tcx> LateLintPass<'tcx> for EqOp {
66 #[allow(clippy::similar_names, clippy::too_many_lines)]
67 fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
68 if let ExprKind::Block(block, _) = e.kind {
69 for stmt in block.stmts {
70 for amn in &ASSERT_MACRO_NAMES {
72 if is_expn_of(stmt.span, amn).is_some();
73 if let StmtKind::Semi(matchexpr) = stmt.kind;
74 if let Some(macro_args) = higher::extract_assert_macro_args(matchexpr);
75 if macro_args.len() == 2;
76 let (lhs, rhs) = (macro_args[0], macro_args[1]);
77 if eq_expr_value(cx, lhs, rhs);
83 lhs.span.to(rhs.span),
84 &format!("identical args used in this `{}!` macro call", amn),
91 if let ExprKind::Binary(op, left, right) = e.kind {
92 if e.span.from_expansion() {
95 let macro_with_not_op = |expr_kind: &ExprKind<'_>| {
96 if let ExprKind::Unary(_, expr) = *expr_kind {
102 if macro_with_not_op(&left.kind) || macro_with_not_op(&right.kind) {
105 if is_useless_with_eq_exprs(higher::binop(op.node)) && eq_expr_value(cx, left, right) {
110 &format!("equal expressions as operands to `{}`", op.node.as_str()),
114 let (trait_id, requires_ref) = match op.node {
115 BinOpKind::Add => (cx.tcx.lang_items().add_trait(), false),
116 BinOpKind::Sub => (cx.tcx.lang_items().sub_trait(), false),
117 BinOpKind::Mul => (cx.tcx.lang_items().mul_trait(), false),
118 BinOpKind::Div => (cx.tcx.lang_items().div_trait(), false),
119 BinOpKind::Rem => (cx.tcx.lang_items().rem_trait(), false),
120 // don't lint short circuiting ops
121 BinOpKind::And | BinOpKind::Or => return,
122 BinOpKind::BitXor => (cx.tcx.lang_items().bitxor_trait(), false),
123 BinOpKind::BitAnd => (cx.tcx.lang_items().bitand_trait(), false),
124 BinOpKind::BitOr => (cx.tcx.lang_items().bitor_trait(), false),
125 BinOpKind::Shl => (cx.tcx.lang_items().shl_trait(), false),
126 BinOpKind::Shr => (cx.tcx.lang_items().shr_trait(), false),
127 BinOpKind::Ne | BinOpKind::Eq => (cx.tcx.lang_items().eq_trait(), true),
128 BinOpKind::Lt | BinOpKind::Le | BinOpKind::Ge | BinOpKind::Gt => {
129 (cx.tcx.lang_items().partial_ord_trait(), true)
132 if let Some(trait_id) = trait_id {
133 #[allow(clippy::match_same_arms)]
134 match (&left.kind, &right.kind) {
135 // do not suggest to dereference literals
136 (&ExprKind::Lit(..), _) | (_, &ExprKind::Lit(..)) => {},
138 (&ExprKind::AddrOf(BorrowKind::Ref, _, l), &ExprKind::AddrOf(BorrowKind::Ref, _, r)) => {
139 let lty = cx.typeck_results().expr_ty(l);
140 let rty = cx.typeck_results().expr_ty(r);
141 let lcpy = is_copy(cx, lty);
142 let rcpy = is_copy(cx, rty);
143 // either operator autorefs or both args are copyable
144 if (requires_ref || (lcpy && rcpy)) && implements_trait(cx, lty, trait_id, &[rty.into()]) {
149 "needlessly taken reference of both operands",
151 let lsnip = snippet(cx, l.span, "...").to_string();
152 let rsnip = snippet(cx, r.span, "...").to_string();
155 "use the values directly",
156 vec![(left.span, lsnip), (right.span, rsnip)],
162 && implements_trait(cx, lty, trait_id, &[cx.typeck_results().expr_ty(right).into()])
168 "needlessly taken reference of left operand",
170 let lsnip = snippet(cx, l.span, "...").to_string();
171 diag.span_suggestion(
173 "use the left value directly",
175 Applicability::MaybeIncorrect, // FIXME #2597
181 && implements_trait(cx, cx.typeck_results().expr_ty(left), trait_id, &[rty.into()])
187 "needlessly taken reference of right operand",
189 let rsnip = snippet(cx, r.span, "...").to_string();
190 diag.span_suggestion(
192 "use the right value directly",
194 Applicability::MaybeIncorrect, // FIXME #2597
201 (&ExprKind::AddrOf(BorrowKind::Ref, _, l), _) => {
202 let lty = cx.typeck_results().expr_ty(l);
203 let lcpy = is_copy(cx, lty);
204 if (requires_ref || lcpy)
205 && implements_trait(cx, lty, trait_id, &[cx.typeck_results().expr_ty(right).into()])
211 "needlessly taken reference of left operand",
213 let lsnip = snippet(cx, l.span, "...").to_string();
214 diag.span_suggestion(
216 "use the left value directly",
218 Applicability::MaybeIncorrect, // FIXME #2597
225 (_, &ExprKind::AddrOf(BorrowKind::Ref, _, r)) => {
226 let rty = cx.typeck_results().expr_ty(r);
227 let rcpy = is_copy(cx, rty);
228 if (requires_ref || rcpy)
229 && implements_trait(cx, cx.typeck_results().expr_ty(left), trait_id, &[rty.into()])
231 span_lint_and_then(cx, OP_REF, e.span, "taken reference of right operand", |diag| {
232 let rsnip = snippet(cx, r.span, "...").to_string();
233 diag.span_suggestion(
235 "use the right value directly",
237 Applicability::MaybeIncorrect, // FIXME #2597