| use crate::utils::{snippet_with_applicability, span_lint_and_sugg}; |
| use rustc_ast::ast::{BinOpKind, Expr, ExprKind, LitKind, UnOp}; |
| use rustc_errors::Applicability; |
| use rustc_lint::{EarlyContext, EarlyLintPass}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| use rustc_span::source_map::Spanned; |
| |
| const ODD_FUNCTIONS_WHITELIST: [&str; 14] = [ |
| "asin", |
| "asinh", |
| "atan", |
| "atanh", |
| "cbrt", |
| "fract", |
| "round", |
| "signum", |
| "sin", |
| "sinh", |
| "tan", |
| "tanh", |
| "to_degrees", |
| "to_radians", |
| ]; |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for operations where precedence may be unclear |
| /// and suggests to add parentheses. Currently it catches the following: |
| /// * mixed usage of arithmetic and bit shifting/combining operators without |
| /// parentheses |
| /// * a "negative" numeric literal (which is really a unary `-` followed by a |
| /// numeric literal) |
| /// followed by a method call |
| /// |
| /// **Why is this bad?** Not everyone knows the precedence of those operators by |
| /// heart, so expressions like these may trip others trying to reason about the |
| /// code. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// * `1 << 2 + 3` equals 32, while `(1 << 2) + 3` equals 7 |
| /// * `-1i32.abs()` equals -1, while `(-1i32).abs()` equals 1 |
| pub PRECEDENCE, |
| complexity, |
| "operations where precedence may be unclear" |
| } |
| |
| declare_lint_pass!(Precedence => [PRECEDENCE]); |
| |
| impl EarlyLintPass for Precedence { |
| fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) { |
| if expr.span.from_expansion() { |
| return; |
| } |
| |
| if let ExprKind::Binary(Spanned { node: op, .. }, ref left, ref right) = expr.kind { |
| let span_sugg = |expr: &Expr, sugg, appl| { |
| span_lint_and_sugg( |
| cx, |
| PRECEDENCE, |
| expr.span, |
| "operator precedence can trip the unwary", |
| "consider parenthesizing your expression", |
| sugg, |
| appl, |
| ); |
| }; |
| |
| if !is_bit_op(op) { |
| return; |
| } |
| let mut applicability = Applicability::MachineApplicable; |
| match (is_arith_expr(left), is_arith_expr(right)) { |
| (true, true) => { |
| let sugg = format!( |
| "({}) {} ({})", |
| snippet_with_applicability(cx, left.span, "..", &mut applicability), |
| op.to_string(), |
| snippet_with_applicability(cx, right.span, "..", &mut applicability) |
| ); |
| span_sugg(expr, sugg, applicability); |
| }, |
| (true, false) => { |
| let sugg = format!( |
| "({}) {} {}", |
| snippet_with_applicability(cx, left.span, "..", &mut applicability), |
| op.to_string(), |
| snippet_with_applicability(cx, right.span, "..", &mut applicability) |
| ); |
| span_sugg(expr, sugg, applicability); |
| }, |
| (false, true) => { |
| let sugg = format!( |
| "{} {} ({})", |
| snippet_with_applicability(cx, left.span, "..", &mut applicability), |
| op.to_string(), |
| snippet_with_applicability(cx, right.span, "..", &mut applicability) |
| ); |
| span_sugg(expr, sugg, applicability); |
| }, |
| (false, false) => (), |
| } |
| } |
| |
| if let ExprKind::Unary(UnOp::Neg, ref rhs) = expr.kind { |
| if let ExprKind::MethodCall(ref path_segment, ref args, _) = rhs.kind { |
| let path_segment_str = path_segment.ident.name.as_str(); |
| if let Some(slf) = args.first() { |
| if let ExprKind::Lit(ref lit) = slf.kind { |
| match lit.kind { |
| LitKind::Int(..) | LitKind::Float(..) => { |
| if ODD_FUNCTIONS_WHITELIST |
| .iter() |
| .any(|odd_function| **odd_function == *path_segment_str) |
| { |
| return; |
| } |
| let mut applicability = Applicability::MachineApplicable; |
| span_lint_and_sugg( |
| cx, |
| PRECEDENCE, |
| expr.span, |
| "unary minus has lower precedence than method call", |
| "consider adding parentheses to clarify your intent", |
| format!( |
| "-({})", |
| snippet_with_applicability(cx, rhs.span, "..", &mut applicability) |
| ), |
| applicability, |
| ); |
| }, |
| _ => (), |
| } |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| fn is_arith_expr(expr: &Expr) -> bool { |
| match expr.kind { |
| ExprKind::Binary(Spanned { node: op, .. }, _, _) => is_arith_op(op), |
| _ => false, |
| } |
| } |
| |
| #[must_use] |
| fn is_bit_op(op: BinOpKind) -> bool { |
| use rustc_ast::ast::BinOpKind::{BitAnd, BitOr, BitXor, Shl, Shr}; |
| match op { |
| BitXor | BitAnd | BitOr | Shl | Shr => true, |
| _ => false, |
| } |
| } |
| |
| #[must_use] |
| fn is_arith_op(op: BinOpKind) -> bool { |
| use rustc_ast::ast::BinOpKind::{Add, Div, Mul, Rem, Sub}; |
| match op { |
| Add | Sub | Mul | Div | Rem => true, |
| _ => false, |
| } |
| } |