| use crate::consts::{ |
| constant, constant_simple, Constant, |
| Constant::{Int, F32, F64}, |
| }; |
| use crate::utils::{eq_expr_value, get_parent_expr, numeric_literal, span_lint_and_sugg, sugg}; |
| use if_chain::if_chain; |
| use rustc_errors::Applicability; |
| use rustc_hir::{BinOpKind, Expr, ExprKind, PathSegment, UnOp}; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_middle::ty; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| use rustc_span::source_map::Spanned; |
| |
| use rustc_ast::ast; |
| use std::f32::consts as f32_consts; |
| use std::f64::consts as f64_consts; |
| use sugg::Sugg; |
| |
| declare_clippy_lint! { |
| /// **What it does:** Looks for floating-point expressions that |
| /// can be expressed using built-in methods to improve accuracy |
| /// at the cost of performance. |
| /// |
| /// **Why is this bad?** Negatively impacts accuracy. |
| /// |
| /// **Known problems:** None |
| /// |
| /// **Example:** |
| /// |
| /// ```rust |
| /// let a = 3f32; |
| /// let _ = a.powf(1.0 / 3.0); |
| /// let _ = (1.0 + a).ln(); |
| /// let _ = a.exp() - 1.0; |
| /// ``` |
| /// |
| /// is better expressed as |
| /// |
| /// ```rust |
| /// let a = 3f32; |
| /// let _ = a.cbrt(); |
| /// let _ = a.ln_1p(); |
| /// let _ = a.exp_m1(); |
| /// ``` |
| pub IMPRECISE_FLOPS, |
| nursery, |
| "usage of imprecise floating point operations" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Looks for floating-point expressions that |
| /// can be expressed using built-in methods to improve both |
| /// accuracy and performance. |
| /// |
| /// **Why is this bad?** Negatively impacts accuracy and performance. |
| /// |
| /// **Known problems:** None |
| /// |
| /// **Example:** |
| /// |
| /// ```rust |
| /// use std::f32::consts::E; |
| /// |
| /// let a = 3f32; |
| /// let _ = (2f32).powf(a); |
| /// let _ = E.powf(a); |
| /// let _ = a.powf(1.0 / 2.0); |
| /// let _ = a.log(2.0); |
| /// let _ = a.log(10.0); |
| /// let _ = a.log(E); |
| /// let _ = a.powf(2.0); |
| /// let _ = a * 2.0 + 4.0; |
| /// let _ = if a < 0.0 { |
| /// -a |
| /// } else { |
| /// a |
| /// }; |
| /// let _ = if a < 0.0 { |
| /// a |
| /// } else { |
| /// -a |
| /// }; |
| /// ``` |
| /// |
| /// is better expressed as |
| /// |
| /// ```rust |
| /// use std::f32::consts::E; |
| /// |
| /// let a = 3f32; |
| /// let _ = a.exp2(); |
| /// let _ = a.exp(); |
| /// let _ = a.sqrt(); |
| /// let _ = a.log2(); |
| /// let _ = a.log10(); |
| /// let _ = a.ln(); |
| /// let _ = a.powi(2); |
| /// let _ = a.mul_add(2.0, 4.0); |
| /// let _ = a.abs(); |
| /// let _ = -a.abs(); |
| /// ``` |
| pub SUBOPTIMAL_FLOPS, |
| nursery, |
| "usage of sub-optimal floating point operations" |
| } |
| |
| declare_lint_pass!(FloatingPointArithmetic => [ |
| IMPRECISE_FLOPS, |
| SUBOPTIMAL_FLOPS |
| ]); |
| |
| // Returns the specialized log method for a given base if base is constant |
| // and is one of 2, 10 and e |
| fn get_specialized_log_method(cx: &LateContext<'_>, base: &Expr<'_>) -> Option<&'static str> { |
| if let Some((value, _)) = constant(cx, cx.typeck_results(), base) { |
| if F32(2.0) == value || F64(2.0) == value { |
| return Some("log2"); |
| } else if F32(10.0) == value || F64(10.0) == value { |
| return Some("log10"); |
| } else if F32(f32_consts::E) == value || F64(f64_consts::E) == value { |
| return Some("ln"); |
| } |
| } |
| |
| None |
| } |
| |
| // Adds type suffixes and parenthesis to method receivers if necessary |
| fn prepare_receiver_sugg<'a>(cx: &LateContext<'_>, mut expr: &'a Expr<'a>) -> Sugg<'a> { |
| let mut suggestion = Sugg::hir(cx, expr, ".."); |
| |
| if let ExprKind::Unary(UnOp::UnNeg, inner_expr) = &expr.kind { |
| expr = &inner_expr; |
| } |
| |
| if_chain! { |
| // if the expression is a float literal and it is unsuffixed then |
| // add a suffix so the suggestion is valid and unambiguous |
| if let ty::Float(float_ty) = cx.typeck_results().expr_ty(expr).kind(); |
| if let ExprKind::Lit(lit) = &expr.kind; |
| if let ast::LitKind::Float(sym, ast::LitFloatType::Unsuffixed) = lit.node; |
| then { |
| let op = format!( |
| "{}{}{}", |
| suggestion, |
| // Check for float literals without numbers following the decimal |
| // separator such as `2.` and adds a trailing zero |
| if sym.as_str().ends_with('.') { |
| "0" |
| } else { |
| "" |
| }, |
| float_ty.name_str() |
| ).into(); |
| |
| suggestion = match suggestion { |
| Sugg::MaybeParen(_) => Sugg::MaybeParen(op), |
| _ => Sugg::NonParen(op) |
| }; |
| } |
| } |
| |
| suggestion.maybe_par() |
| } |
| |
| fn check_log_base(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) { |
| if let Some(method) = get_specialized_log_method(cx, &args[1]) { |
| span_lint_and_sugg( |
| cx, |
| SUBOPTIMAL_FLOPS, |
| expr.span, |
| "logarithm for bases 2, 10 and e can be computed more accurately", |
| "consider using", |
| format!("{}.{}()", Sugg::hir(cx, &args[0], ".."), method), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| |
| // TODO: Lint expressions of the form `(x + y).ln()` where y > 1 and |
| // suggest usage of `(x + (y - 1)).ln_1p()` instead |
| fn check_ln1p(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) { |
| if let ExprKind::Binary( |
| Spanned { |
| node: BinOpKind::Add, .. |
| }, |
| lhs, |
| rhs, |
| ) = &args[0].kind |
| { |
| let recv = match ( |
| constant(cx, cx.typeck_results(), lhs), |
| constant(cx, cx.typeck_results(), rhs), |
| ) { |
| (Some((value, _)), _) if F32(1.0) == value || F64(1.0) == value => rhs, |
| (_, Some((value, _))) if F32(1.0) == value || F64(1.0) == value => lhs, |
| _ => return, |
| }; |
| |
| span_lint_and_sugg( |
| cx, |
| IMPRECISE_FLOPS, |
| expr.span, |
| "ln(1 + x) can be computed more accurately", |
| "consider using", |
| format!("{}.ln_1p()", prepare_receiver_sugg(cx, recv)), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| |
| // Returns an integer if the float constant is a whole number and it can be |
| // converted to an integer without loss of precision. For now we only check |
| // ranges [-16777215, 16777216) for type f32 as whole number floats outside |
| // this range are lossy and ambiguous. |
| #[allow(clippy::cast_possible_truncation)] |
| fn get_integer_from_float_constant(value: &Constant) -> Option<i32> { |
| match value { |
| F32(num) if num.fract() == 0.0 => { |
| if (-16_777_215.0..16_777_216.0).contains(num) { |
| Some(num.round() as i32) |
| } else { |
| None |
| } |
| }, |
| F64(num) if num.fract() == 0.0 => { |
| if (-2_147_483_648.0..2_147_483_648.0).contains(num) { |
| Some(num.round() as i32) |
| } else { |
| None |
| } |
| }, |
| _ => None, |
| } |
| } |
| |
| fn check_powf(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) { |
| // Check receiver |
| if let Some((value, _)) = constant(cx, cx.typeck_results(), &args[0]) { |
| let method = if F32(f32_consts::E) == value || F64(f64_consts::E) == value { |
| "exp" |
| } else if F32(2.0) == value || F64(2.0) == value { |
| "exp2" |
| } else { |
| return; |
| }; |
| |
| span_lint_and_sugg( |
| cx, |
| SUBOPTIMAL_FLOPS, |
| expr.span, |
| "exponent for bases 2 and e can be computed more accurately", |
| "consider using", |
| format!("{}.{}()", prepare_receiver_sugg(cx, &args[1]), method), |
| Applicability::MachineApplicable, |
| ); |
| } |
| |
| // Check argument |
| if let Some((value, _)) = constant(cx, cx.typeck_results(), &args[1]) { |
| let (lint, help, suggestion) = if F32(1.0 / 2.0) == value || F64(1.0 / 2.0) == value { |
| ( |
| SUBOPTIMAL_FLOPS, |
| "square-root of a number can be computed more efficiently and accurately", |
| format!("{}.sqrt()", Sugg::hir(cx, &args[0], "..")), |
| ) |
| } else if F32(1.0 / 3.0) == value || F64(1.0 / 3.0) == value { |
| ( |
| IMPRECISE_FLOPS, |
| "cube-root of a number can be computed more accurately", |
| format!("{}.cbrt()", Sugg::hir(cx, &args[0], "..")), |
| ) |
| } else if let Some(exponent) = get_integer_from_float_constant(&value) { |
| ( |
| SUBOPTIMAL_FLOPS, |
| "exponentiation with integer powers can be computed more efficiently", |
| format!( |
| "{}.powi({})", |
| Sugg::hir(cx, &args[0], ".."), |
| numeric_literal::format(&exponent.to_string(), None, false) |
| ), |
| ) |
| } else { |
| return; |
| }; |
| |
| span_lint_and_sugg( |
| cx, |
| lint, |
| expr.span, |
| help, |
| "consider using", |
| suggestion, |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| |
| fn check_powi(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) { |
| if let Some((value, _)) = constant(cx, cx.typeck_results(), &args[1]) { |
| if value == Int(2) { |
| if let Some(parent) = get_parent_expr(cx, expr) { |
| if let Some(grandparent) = get_parent_expr(cx, parent) { |
| if let ExprKind::MethodCall(PathSegment { ident: method_name, .. }, _, args, _) = grandparent.kind { |
| if method_name.as_str() == "sqrt" && detect_hypot(cx, args).is_some() { |
| return; |
| } |
| } |
| } |
| |
| if let ExprKind::Binary( |
| Spanned { |
| node: BinOpKind::Add, .. |
| }, |
| ref lhs, |
| ref rhs, |
| ) = parent.kind |
| { |
| let other_addend = if lhs.hir_id == expr.hir_id { rhs } else { lhs }; |
| |
| span_lint_and_sugg( |
| cx, |
| SUBOPTIMAL_FLOPS, |
| parent.span, |
| "square can be computed more efficiently", |
| "consider using", |
| format!( |
| "{}.mul_add({}, {})", |
| Sugg::hir(cx, &args[0], ".."), |
| Sugg::hir(cx, &args[0], ".."), |
| Sugg::hir(cx, &other_addend, ".."), |
| ), |
| Applicability::MachineApplicable, |
| ); |
| |
| return; |
| } |
| } |
| |
| span_lint_and_sugg( |
| cx, |
| SUBOPTIMAL_FLOPS, |
| expr.span, |
| "square can be computed more efficiently", |
| "consider using", |
| format!("{} * {}", Sugg::hir(cx, &args[0], ".."), Sugg::hir(cx, &args[0], "..")), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |
| |
| fn detect_hypot(cx: &LateContext<'_>, args: &[Expr<'_>]) -> Option<String> { |
| if let ExprKind::Binary( |
| Spanned { |
| node: BinOpKind::Add, .. |
| }, |
| ref add_lhs, |
| ref add_rhs, |
| ) = args[0].kind |
| { |
| // check if expression of the form x * x + y * y |
| if_chain! { |
| if let ExprKind::Binary(Spanned { node: BinOpKind::Mul, .. }, ref lmul_lhs, ref lmul_rhs) = add_lhs.kind; |
| if let ExprKind::Binary(Spanned { node: BinOpKind::Mul, .. }, ref rmul_lhs, ref rmul_rhs) = add_rhs.kind; |
| if eq_expr_value(cx, lmul_lhs, lmul_rhs); |
| if eq_expr_value(cx, rmul_lhs, rmul_rhs); |
| then { |
| return Some(format!("{}.hypot({})", Sugg::hir(cx, &lmul_lhs, ".."), Sugg::hir(cx, &rmul_lhs, ".."))); |
| } |
| } |
| |
| // check if expression of the form x.powi(2) + y.powi(2) |
| if_chain! { |
| if let ExprKind::MethodCall( |
| PathSegment { ident: lmethod_name, .. }, |
| ref _lspan, |
| ref largs, |
| _ |
| ) = add_lhs.kind; |
| if let ExprKind::MethodCall( |
| PathSegment { ident: rmethod_name, .. }, |
| ref _rspan, |
| ref rargs, |
| _ |
| ) = add_rhs.kind; |
| if lmethod_name.as_str() == "powi" && rmethod_name.as_str() == "powi"; |
| if let Some((lvalue, _)) = constant(cx, cx.typeck_results(), &largs[1]); |
| if let Some((rvalue, _)) = constant(cx, cx.typeck_results(), &rargs[1]); |
| if Int(2) == lvalue && Int(2) == rvalue; |
| then { |
| return Some(format!("{}.hypot({})", Sugg::hir(cx, &largs[0], ".."), Sugg::hir(cx, &rargs[0], ".."))); |
| } |
| } |
| } |
| |
| None |
| } |
| |
| fn check_hypot(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) { |
| if let Some(message) = detect_hypot(cx, args) { |
| span_lint_and_sugg( |
| cx, |
| IMPRECISE_FLOPS, |
| expr.span, |
| "hypotenuse can be computed more accurately", |
| "consider using", |
| message, |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| |
| // TODO: Lint expressions of the form `x.exp() - y` where y > 1 |
| // and suggest usage of `x.exp_m1() - (y - 1)` instead |
| fn check_expm1(cx: &LateContext<'_>, expr: &Expr<'_>) { |
| if_chain! { |
| if let ExprKind::Binary(Spanned { node: BinOpKind::Sub, .. }, ref lhs, ref rhs) = expr.kind; |
| if cx.typeck_results().expr_ty(lhs).is_floating_point(); |
| if let Some((value, _)) = constant(cx, cx.typeck_results(), rhs); |
| if F32(1.0) == value || F64(1.0) == value; |
| if let ExprKind::MethodCall(ref path, _, ref method_args, _) = lhs.kind; |
| if cx.typeck_results().expr_ty(&method_args[0]).is_floating_point(); |
| if path.ident.name.as_str() == "exp"; |
| then { |
| span_lint_and_sugg( |
| cx, |
| IMPRECISE_FLOPS, |
| expr.span, |
| "(e.pow(x) - 1) can be computed more accurately", |
| "consider using", |
| format!( |
| "{}.exp_m1()", |
| Sugg::hir(cx, &method_args[0], "..") |
| ), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |
| |
| fn is_float_mul_expr<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<(&'a Expr<'a>, &'a Expr<'a>)> { |
| if_chain! { |
| if let ExprKind::Binary(Spanned { node: BinOpKind::Mul, .. }, ref lhs, ref rhs) = &expr.kind; |
| if cx.typeck_results().expr_ty(lhs).is_floating_point(); |
| if cx.typeck_results().expr_ty(rhs).is_floating_point(); |
| then { |
| return Some((lhs, rhs)); |
| } |
| } |
| |
| None |
| } |
| |
| // TODO: Fix rust-lang/rust-clippy#4735 |
| fn check_mul_add(cx: &LateContext<'_>, expr: &Expr<'_>) { |
| if let ExprKind::Binary( |
| Spanned { |
| node: BinOpKind::Add, .. |
| }, |
| lhs, |
| rhs, |
| ) = &expr.kind |
| { |
| if let Some(parent) = get_parent_expr(cx, expr) { |
| if let ExprKind::MethodCall(PathSegment { ident: method_name, .. }, _, args, _) = parent.kind { |
| if method_name.as_str() == "sqrt" && detect_hypot(cx, args).is_some() { |
| return; |
| } |
| } |
| } |
| |
| let (recv, arg1, arg2) = if let Some((inner_lhs, inner_rhs)) = is_float_mul_expr(cx, lhs) { |
| (inner_lhs, inner_rhs, rhs) |
| } else if let Some((inner_lhs, inner_rhs)) = is_float_mul_expr(cx, rhs) { |
| (inner_lhs, inner_rhs, lhs) |
| } else { |
| return; |
| }; |
| |
| span_lint_and_sugg( |
| cx, |
| SUBOPTIMAL_FLOPS, |
| expr.span, |
| "multiply and add expressions can be calculated more efficiently and accurately", |
| "consider using", |
| format!( |
| "{}.mul_add({}, {})", |
| prepare_receiver_sugg(cx, recv), |
| Sugg::hir(cx, arg1, ".."), |
| Sugg::hir(cx, arg2, ".."), |
| ), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| |
| /// Returns true iff expr is an expression which tests whether or not |
| /// test is positive or an expression which tests whether or not test |
| /// is nonnegative. |
| /// Used for check-custom-abs function below |
| fn is_testing_positive(cx: &LateContext<'_>, expr: &Expr<'_>, test: &Expr<'_>) -> bool { |
| if let ExprKind::Binary(Spanned { node: op, .. }, left, right) = expr.kind { |
| match op { |
| BinOpKind::Gt | BinOpKind::Ge => is_zero(cx, right) && eq_expr_value(cx, left, test), |
| BinOpKind::Lt | BinOpKind::Le => is_zero(cx, left) && eq_expr_value(cx, right, test), |
| _ => false, |
| } |
| } else { |
| false |
| } |
| } |
| |
| /// See [`is_testing_positive`] |
| fn is_testing_negative(cx: &LateContext<'_>, expr: &Expr<'_>, test: &Expr<'_>) -> bool { |
| if let ExprKind::Binary(Spanned { node: op, .. }, left, right) = expr.kind { |
| match op { |
| BinOpKind::Gt | BinOpKind::Ge => is_zero(cx, left) && eq_expr_value(cx, right, test), |
| BinOpKind::Lt | BinOpKind::Le => is_zero(cx, right) && eq_expr_value(cx, left, test), |
| _ => false, |
| } |
| } else { |
| false |
| } |
| } |
| |
| /// Returns true iff expr is some zero literal |
| fn is_zero(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool { |
| match constant_simple(cx, cx.typeck_results(), expr) { |
| Some(Constant::Int(i)) => i == 0, |
| Some(Constant::F32(f)) => f == 0.0, |
| Some(Constant::F64(f)) => f == 0.0, |
| _ => false, |
| } |
| } |
| |
| /// If the two expressions are negations of each other, then it returns |
| /// a tuple, in which the first element is true iff expr1 is the |
| /// positive expressions, and the second element is the positive |
| /// one of the two expressions |
| /// If the two expressions are not negations of each other, then it |
| /// returns None. |
| fn are_negated<'a>(cx: &LateContext<'_>, expr1: &'a Expr<'a>, expr2: &'a Expr<'a>) -> Option<(bool, &'a Expr<'a>)> { |
| if let ExprKind::Unary(UnOp::UnNeg, expr1_negated) = &expr1.kind { |
| if eq_expr_value(cx, expr1_negated, expr2) { |
| return Some((false, expr2)); |
| } |
| } |
| if let ExprKind::Unary(UnOp::UnNeg, expr2_negated) = &expr2.kind { |
| if eq_expr_value(cx, expr1, expr2_negated) { |
| return Some((true, expr1)); |
| } |
| } |
| None |
| } |
| |
| fn check_custom_abs(cx: &LateContext<'_>, expr: &Expr<'_>) { |
| if_chain! { |
| if let ExprKind::If(cond, body, else_body) = expr.kind; |
| if let ExprKind::Block(block, _) = body.kind; |
| if block.stmts.is_empty(); |
| if let Some(if_body_expr) = block.expr; |
| if let Some(ExprKind::Block(else_block, _)) = else_body.map(|el| &el.kind); |
| if else_block.stmts.is_empty(); |
| if let Some(else_body_expr) = else_block.expr; |
| if let Some((if_expr_positive, body)) = are_negated(cx, if_body_expr, else_body_expr); |
| then { |
| let positive_abs_sugg = ( |
| "manual implementation of `abs` method", |
| format!("{}.abs()", Sugg::hir(cx, body, "..")), |
| ); |
| let negative_abs_sugg = ( |
| "manual implementation of negation of `abs` method", |
| format!("-{}.abs()", Sugg::hir(cx, body, "..")), |
| ); |
| let sugg = if is_testing_positive(cx, cond, body) { |
| if if_expr_positive { |
| positive_abs_sugg |
| } else { |
| negative_abs_sugg |
| } |
| } else if is_testing_negative(cx, cond, body) { |
| if if_expr_positive { |
| negative_abs_sugg |
| } else { |
| positive_abs_sugg |
| } |
| } else { |
| return; |
| }; |
| span_lint_and_sugg( |
| cx, |
| SUBOPTIMAL_FLOPS, |
| expr.span, |
| sugg.0, |
| "try", |
| sugg.1, |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |
| |
| fn are_same_base_logs(cx: &LateContext<'_>, expr_a: &Expr<'_>, expr_b: &Expr<'_>) -> bool { |
| if_chain! { |
| if let ExprKind::MethodCall(PathSegment { ident: method_name_a, .. }, _, ref args_a, _) = expr_a.kind; |
| if let ExprKind::MethodCall(PathSegment { ident: method_name_b, .. }, _, ref args_b, _) = expr_b.kind; |
| then { |
| return method_name_a.as_str() == method_name_b.as_str() && |
| args_a.len() == args_b.len() && |
| ( |
| ["ln", "log2", "log10"].contains(&&*method_name_a.as_str()) || |
| method_name_a.as_str() == "log" && args_a.len() == 2 && eq_expr_value(cx, &args_a[1], &args_b[1]) |
| ); |
| } |
| } |
| |
| false |
| } |
| |
| fn check_log_division(cx: &LateContext<'_>, expr: &Expr<'_>) { |
| // check if expression of the form x.logN() / y.logN() |
| if_chain! { |
| if let ExprKind::Binary( |
| Spanned { |
| node: BinOpKind::Div, .. |
| }, |
| lhs, |
| rhs, |
| ) = &expr.kind; |
| if are_same_base_logs(cx, lhs, rhs); |
| if let ExprKind::MethodCall(_, _, ref largs, _) = lhs.kind; |
| if let ExprKind::MethodCall(_, _, ref rargs, _) = rhs.kind; |
| then { |
| span_lint_and_sugg( |
| cx, |
| SUBOPTIMAL_FLOPS, |
| expr.span, |
| "log base can be expressed more clearly", |
| "consider using", |
| format!("{}.log({})", Sugg::hir(cx, &largs[0], ".."), Sugg::hir(cx, &rargs[0], ".."),), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |
| |
| fn check_radians(cx: &LateContext<'_>, expr: &Expr<'_>) { |
| if_chain! { |
| if let ExprKind::Binary( |
| Spanned { |
| node: BinOpKind::Div, .. |
| }, |
| div_lhs, |
| div_rhs, |
| ) = &expr.kind; |
| if let ExprKind::Binary( |
| Spanned { |
| node: BinOpKind::Mul, .. |
| }, |
| mul_lhs, |
| mul_rhs, |
| ) = &div_lhs.kind; |
| if let Some((rvalue, _)) = constant(cx, cx.typeck_results(), div_rhs); |
| if let Some((lvalue, _)) = constant(cx, cx.typeck_results(), mul_rhs); |
| then { |
| // TODO: also check for constant values near PI/180 or 180/PI |
| if (F32(f32_consts::PI) == rvalue || F64(f64_consts::PI) == rvalue) && |
| (F32(180_f32) == lvalue || F64(180_f64) == lvalue) |
| { |
| span_lint_and_sugg( |
| cx, |
| SUBOPTIMAL_FLOPS, |
| expr.span, |
| "conversion to degrees can be done more accurately", |
| "consider using", |
| format!("{}.to_degrees()", Sugg::hir(cx, &mul_lhs, "..")), |
| Applicability::MachineApplicable, |
| ); |
| } else if |
| (F32(180_f32) == rvalue || F64(180_f64) == rvalue) && |
| (F32(f32_consts::PI) == lvalue || F64(f64_consts::PI) == lvalue) |
| { |
| span_lint_and_sugg( |
| cx, |
| SUBOPTIMAL_FLOPS, |
| expr.span, |
| "conversion to radians can be done more accurately", |
| "consider using", |
| format!("{}.to_radians()", Sugg::hir(cx, &mul_lhs, "..")), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |
| } |
| |
| impl<'tcx> LateLintPass<'tcx> for FloatingPointArithmetic { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| if let ExprKind::MethodCall(ref path, _, args, _) = &expr.kind { |
| let recv_ty = cx.typeck_results().expr_ty(&args[0]); |
| |
| if recv_ty.is_floating_point() { |
| match &*path.ident.name.as_str() { |
| "ln" => check_ln1p(cx, expr, args), |
| "log" => check_log_base(cx, expr, args), |
| "powf" => check_powf(cx, expr, args), |
| "powi" => check_powi(cx, expr, args), |
| "sqrt" => check_hypot(cx, expr, args), |
| _ => {}, |
| } |
| } |
| } else { |
| check_expm1(cx, expr); |
| check_mul_add(cx, expr); |
| check_custom_abs(cx, expr); |
| check_log_division(cx, expr); |
| check_radians(cx, expr); |
| } |
| } |
| } |