use crate::consts::{
- constant, Constant,
- Constant::{F32, F64},
+ constant, constant_simple, Constant,
+ Constant::{Int, F32, F64},
};
-use crate::utils::*;
+use crate::utils::{eq_expr_value, get_parent_expr, numeric_literal, span_lint_and_sugg, sugg};
use if_chain::if_chain;
-use rustc::declare_lint_pass;
-use rustc::hir::*;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
use rustc_errors::Applicability;
-use rustc_session::declare_tool_lint;
+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,
- /// performance and/or succinctness.
+ /// can be expressed using built-in methods to improve accuracy
+ /// at the cost of performance.
///
- /// **Why is this bad?** Negatively affects accuracy, performance
- /// and/or readability.
+ /// **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
///
/// let _ = (2f32).powf(a);
/// let _ = E.powf(a);
/// let _ = a.powf(1.0 / 2.0);
- /// let _ = a.powf(1.0 / 3.0);
/// let _ = a.log(2.0);
/// let _ = a.log(10.0);
/// let _ = a.log(E);
- /// let _ = (1.0 + a).ln();
- /// let _ = a.exp() - 1.0;
/// 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
/// let _ = a.exp2();
/// let _ = a.exp();
/// let _ = a.sqrt();
- /// let _ = a.cbrt();
/// let _ = a.log2();
/// let _ = a.log10();
/// let _ = a.ln();
- /// let _ = a.ln_1p();
- /// let _ = a.exp_m1();
/// let _ = a.powi(2);
+ /// let _ = a.mul_add(2.0, 4.0);
+ /// let _ = a.abs();
+ /// let _ = -a.abs();
/// ```
- pub FLOATING_POINT_IMPROVEMENTS,
+ pub SUBOPTIMAL_FLOPS,
nursery,
- "looks for improvements to floating-point expressions"
+ "usage of sub-optimal floating point operations"
}
-declare_lint_pass!(FloatingPointArithmetic => [FLOATING_POINT_IMPROVEMENTS]);
-
-fn check_log_base(cx: &LateContext<'_, '_>, expr: &Expr, args: &HirVec<Expr>) {
- let arg = sugg::Sugg::hir(cx, &args[0], "..").maybe_par();
-
- if let Some((value, _)) = constant(cx, cx.tables, &args[1]) {
- let method;
+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 {
- method = "log2";
+ return Some("log2");
} else if F32(10.0) == value || F64(10.0) == value {
- method = "log10";
+ return Some("log10");
} else if F32(f32_consts::E) == value || F64(f64_consts::E) == value {
- method = "ln";
- } else {
- return;
+ 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::Neg, 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,
- FLOATING_POINT_IMPROVEMENTS,
+ SUBOPTIMAL_FLOPS,
expr.span,
"logarithm for bases 2, 10 and e can be computed more accurately",
"consider using",
- format!("{}.{}()", arg, method),
+ format!("{}.{}()", Sugg::hir(cx, &args[0], ".."), method),
Applicability::MachineApplicable,
);
}
}
-// TODO: Lint expressions of the form `(x + 1).ln()` and `(x + y).ln()`
-// where y > 1 and suggest usage of `(x + (y - 1)).ln_1p()` instead
-fn check_ln1p(cx: &LateContext<'_, '_>, expr: &Expr, args: &HirVec<Expr>) {
- if_chain! {
- if let ExprKind::Binary(op, ref lhs, ref rhs) = &args[0].kind;
- if op.node == BinOpKind::Add;
- if let Some((value, _)) = constant(cx, cx.tables, lhs);
- if F32(1.0) == value || F64(1.0) == value;
- then {
- let arg = sugg::Sugg::hir(cx, rhs, "..").maybe_par();
+// 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,
- FLOATING_POINT_IMPROVEMENTS,
- expr.span,
- "ln(1 + x) can be computed more accurately",
- "consider using",
- format!("{}.ln_1p()", arg),
- Applicability::MachineApplicable,
- );
- }
+ 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
-// TODO: Add a better check to determine whether the float can be
-// casted without loss
+// 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<i64> {
+fn get_integer_from_float_constant(value: &Constant) -> Option<i32> {
match value {
- F32(num) if (num.trunc() - num).abs() <= std::f32::EPSILON => {
- if *num > -16_777_217.0 && *num < 16_777_217.0 {
- Some(num.round() as i64)
+ 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.trunc() - num).abs() <= std::f64::EPSILON => {
- if *num > -9_007_199_254_740_993.0 && *num < 9_007_199_254_740_993.0 {
- Some(num.round() as i64)
+ 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
}
}
}
-fn check_powf(cx: &LateContext<'_, '_>, expr: &Expr, args: &HirVec<Expr>) {
+fn check_powf(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
// Check receiver
- if let Some((value, _)) = constant(cx, cx.tables, &args[0]) {
- let method;
-
- if F32(f32_consts::E) == value || F64(f64_consts::E) == value {
- method = "exp";
+ 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 {
- method = "exp2";
+ "exp2"
} else {
return;
- }
+ };
span_lint_and_sugg(
cx,
- FLOATING_POINT_IMPROVEMENTS,
+ SUBOPTIMAL_FLOPS,
expr.span,
"exponent for bases 2 and e can be computed more accurately",
"consider using",
- format!("{}.{}()", sugg::Sugg::hir(cx, &args[1], "..").maybe_par(), method),
+ format!("{}.{}()", prepare_receiver_sugg(cx, &args[1]), method),
Applicability::MachineApplicable,
);
}
// Check argument
- if let Some((value, _)) = constant(cx, cx.tables, &args[1]) {
- let help;
- let method;
-
- if F32(1.0 / 2.0) == value || F64(1.0 / 2.0) == value {
- help = "square-root of a number can be computed more efficiently and accurately";
- method = "sqrt";
+ 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 {
- help = "cube-root of a number can be computed more accurately";
- method = "cbrt";
+ (
+ 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,
- FLOATING_POINT_IMPROVEMENTS,
+ SUBOPTIMAL_FLOPS,
expr.span,
- "exponentiation with integer powers can be computed more efficiently",
+ "square can be computed more efficiently",
"consider using",
- format!("{}.powi({})", sugg::Sugg::hir(cx, &args[0], ".."), exponent),
+ format!("{} * {}", Sugg::hir(cx, &args[0], ".."), Sugg::hir(cx, &args[0], "..")),
Applicability::MachineApplicable,
);
+ }
+ }
+}
- return;
- } else {
- return;
+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,
- FLOATING_POINT_IMPROVEMENTS,
+ IMPRECISE_FLOPS,
expr.span,
- help,
+ "hypotenuse can be computed more accurately",
"consider using",
- format!("{}.{}()", sugg::Sugg::hir(cx, &args[0], ".."), method),
+ 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) {
+fn check_expm1(cx: &LateContext<'_>, expr: &Expr<'_>) {
if_chain! {
- if let ExprKind::Binary(op, ref lhs, ref rhs) = expr.kind;
- if op.node == BinOpKind::Sub;
- if cx.tables.expr_ty(lhs).is_floating_point();
- if let Some((value, _)) = constant(cx, cx.tables, rhs);
+ 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 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,
- FLOATING_POINT_IMPROVEMENTS,
+ IMPRECISE_FLOPS,
expr.span,
"(e.pow(x) - 1) can be computed more accurately",
"consider using",
format!(
"{}.exp_m1()",
- sugg::Sugg::hir(cx, &method_args[0], "..")
+ Sugg::hir(cx, &method_args[0], "..")
),
Applicability::MachineApplicable,
);
}
}
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for FloatingPointArithmetic {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
- if let ExprKind::MethodCall(ref path, _, args) = &expr.kind {
- let recv_ty = cx.tables.expr_ty(&args[0]);
+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::Neg, expr1_negated) = &expr1.kind {
+ if eq_expr_value(cx, expr1_negated, expr2) {
+ return Some((false, expr2));
+ }
+ }
+ if let ExprKind::Unary(UnOp::Neg, 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);
}
}
}
projects / rust.git / blobdiff