2019-08-19 16:30:32 +00:00
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use crate::utils::{snippet_with_applicability, span_lint_and_sugg};
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2020-03-01 03:23:33 +00:00
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use rustc_ast::ast::{BinOpKind, Expr, ExprKind, LitKind, UnOp};
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2018-12-29 15:04:45 +00:00
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use rustc_errors::Applicability;
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2020-01-12 06:08:41 +00:00
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use rustc_lint::{EarlyContext, EarlyLintPass};
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2020-01-11 11:37:08 +00:00
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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2020-01-04 10:00:00 +00:00
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use rustc_span::source_map::Spanned;
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2015-08-30 15:32:35 +00:00
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2018-03-28 13:24:26 +00:00
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declare_clippy_lint! {
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2019-03-05 16:50:33 +00:00
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/// **What it does:** Checks for operations where precedence may be unclear
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/// and suggests to add parentheses. Currently it catches the following:
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/// * mixed usage of arithmetic and bit shifting/combining operators without
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/// parentheses
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/// * a "negative" numeric literal (which is really a unary `-` followed by a
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/// numeric literal)
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/// followed by a method call
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///
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/// **Why is this bad?** Not everyone knows the precedence of those operators by
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/// heart, so expressions like these may trip others trying to reason about the
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/// code.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// * `1 << 2 + 3` equals 32, while `(1 << 2) + 3` equals 7
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/// * `-1i32.abs()` equals -1, while `(-1i32).abs()` equals 1
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2016-08-06 08:18:36 +00:00
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pub PRECEDENCE,
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2018-03-28 13:24:26 +00:00
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complexity,
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2016-08-06 08:18:36 +00:00
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"operations where precedence may be unclear"
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2016-02-05 23:13:29 +00:00
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}
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2015-08-30 15:32:35 +00:00
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2019-04-08 20:43:55 +00:00
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declare_lint_pass!(Precedence => [PRECEDENCE]);
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2015-08-30 15:32:35 +00:00
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2015-09-19 02:53:04 +00:00
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impl EarlyLintPass for Precedence {
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2018-07-23 11:01:12 +00:00
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fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
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2019-08-19 16:30:32 +00:00
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if expr.span.from_expansion() {
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2018-01-16 14:52:16 +00:00
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return;
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}
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2019-09-27 15:16:06 +00:00
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if let ExprKind::Binary(Spanned { node: op, .. }, ref left, ref right) = expr.kind {
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2018-11-27 14:13:57 +00:00
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let span_sugg = |expr: &Expr, sugg, appl| {
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2017-08-09 07:30:56 +00:00
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span_lint_and_sugg(
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cx,
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PRECEDENCE,
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expr.span,
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"operator precedence can trip the unwary",
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"consider parenthesizing your expression",
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sugg,
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2018-11-27 14:13:57 +00:00
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appl,
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2017-08-09 07:30:56 +00:00
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);
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2017-06-29 14:07:43 +00:00
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};
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2017-01-22 13:51:13 +00:00
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2016-01-04 04:26:12 +00:00
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if !is_bit_op(op) {
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return;
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}
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2018-11-27 14:13:57 +00:00
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let mut applicability = Applicability::MachineApplicable;
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2015-10-13 11:48:48 +00:00
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match (is_arith_expr(left), is_arith_expr(right)) {
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2015-12-31 20:39:03 +00:00
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(true, true) => {
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2017-08-09 07:30:56 +00:00
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let sugg = format!(
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"({}) {} ({})",
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2018-11-27 14:13:57 +00:00
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snippet_with_applicability(cx, left.span, "..", &mut applicability),
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2017-08-09 07:30:56 +00:00
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op.to_string(),
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2018-11-27 14:13:57 +00:00
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snippet_with_applicability(cx, right.span, "..", &mut applicability)
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2017-08-09 07:30:56 +00:00
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);
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2018-11-27 14:13:57 +00:00
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span_sugg(expr, sugg, applicability);
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2016-12-20 17:21:30 +00:00
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},
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2015-12-31 20:39:03 +00:00
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(true, false) => {
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2017-08-09 07:30:56 +00:00
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let sugg = format!(
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"({}) {} {}",
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2018-11-27 14:13:57 +00:00
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snippet_with_applicability(cx, left.span, "..", &mut applicability),
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2017-08-09 07:30:56 +00:00
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op.to_string(),
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2018-11-27 14:13:57 +00:00
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snippet_with_applicability(cx, right.span, "..", &mut applicability)
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2017-08-09 07:30:56 +00:00
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);
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2018-11-27 14:13:57 +00:00
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span_sugg(expr, sugg, applicability);
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2016-12-20 17:21:30 +00:00
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},
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2015-12-31 20:39:03 +00:00
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(false, true) => {
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2017-08-09 07:30:56 +00:00
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let sugg = format!(
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"{} {} ({})",
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2018-11-27 14:13:57 +00:00
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snippet_with_applicability(cx, left.span, "..", &mut applicability),
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2017-08-09 07:30:56 +00:00
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op.to_string(),
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2018-11-27 14:13:57 +00:00
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snippet_with_applicability(cx, right.span, "..", &mut applicability)
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2017-08-09 07:30:56 +00:00
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);
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2018-11-27 14:13:57 +00:00
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span_sugg(expr, sugg, applicability);
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2016-12-20 17:21:30 +00:00
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},
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2017-01-22 13:51:13 +00:00
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(false, false) => (),
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2015-08-30 15:32:35 +00:00
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}
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}
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2019-09-27 15:16:06 +00:00
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if let ExprKind::Unary(UnOp::Neg, ref rhs) = expr.kind {
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if let ExprKind::MethodCall(_, ref args) = rhs.kind {
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2015-08-30 15:32:35 +00:00
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if let Some(slf) = args.first() {
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2019-09-27 15:16:06 +00:00
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if let ExprKind::Lit(ref lit) = slf.kind {
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match lit.kind {
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2019-11-07 12:27:00 +00:00
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LitKind::Int(..) | LitKind::Float(..) => {
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2018-11-27 14:13:57 +00:00
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let mut applicability = Applicability::MachineApplicable;
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2017-08-09 07:30:56 +00:00
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span_lint_and_sugg(
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cx,
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PRECEDENCE,
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expr.span,
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"unary minus has lower precedence than method call",
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"consider adding parentheses to clarify your intent",
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2018-11-27 20:14:15 +00:00
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format!(
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"-({})",
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snippet_with_applicability(cx, rhs.span, "..", &mut applicability)
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),
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2018-11-27 14:13:57 +00:00
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applicability,
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2017-08-09 07:30:56 +00:00
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);
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2016-12-20 17:21:30 +00:00
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},
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2016-01-04 04:26:12 +00:00
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_ => (),
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2015-08-30 15:32:35 +00:00
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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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2015-11-17 05:22:57 +00:00
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fn is_arith_expr(expr: &Expr) -> bool {
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2019-09-27 15:16:06 +00:00
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match expr.kind {
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2016-04-14 18:14:03 +00:00
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ExprKind::Binary(Spanned { node: op, .. }, _, _) => is_arith_op(op),
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2016-01-04 04:26:12 +00:00
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_ => false,
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2015-08-30 15:32:35 +00:00
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}
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}
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2019-09-18 06:37:41 +00:00
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#[must_use]
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2016-02-12 17:35:44 +00:00
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fn is_bit_op(op: BinOpKind) -> bool {
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2020-03-01 03:23:33 +00:00
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use rustc_ast::ast::BinOpKind::{BitAnd, BitOr, BitXor, Shl, Shr};
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2015-08-30 15:32:35 +00:00
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match op {
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2016-02-12 17:35:44 +00:00
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BitXor | BitAnd | BitOr | Shl | Shr => true,
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2016-01-04 04:26:12 +00:00
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_ => false,
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2015-08-30 15:32:35 +00:00
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}
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}
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2019-09-18 06:37:41 +00:00
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#[must_use]
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2016-02-12 17:35:44 +00:00
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fn is_arith_op(op: BinOpKind) -> bool {
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2020-03-01 03:23:33 +00:00
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use rustc_ast::ast::BinOpKind::{Add, Div, Mul, Rem, Sub};
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2015-08-30 15:32:35 +00:00
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match op {
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2016-02-12 17:35:44 +00:00
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Add | Sub | Mul | Div | Rem => true,
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2016-01-04 04:26:12 +00:00
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_ => false,
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2015-08-30 15:32:35 +00:00
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}
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}
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