use crate::utils::span_lint;
-use rustc::declare_lint_pass;
-use rustc::hir::*;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc_session::declare_tool_lint;
+use rustc_ast::ast::{FloatTy, LitFloatType, LitKind};
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::symbol;
use std::f64::consts as f64;
-use syntax::ast::{FloatTy, LitFloatType, LitKind};
-use syntax::symbol;
declare_clippy_lint! {
/// **What it does:** Checks for floating point literals that approximate
///
/// **Example:**
/// ```rust
- /// // Bad
/// let x = 3.14;
/// let y = 1_f64 / x;
- ///
- /// // Good
+ /// ```
+ /// Use predefined constants instead:
+ /// ```rust
/// let x = std::f32::consts::PI;
/// let y = std::f64::consts::FRAC_1_PI;
/// ```
}
// Tuples are of the form (constant, name, min_digits)
-const KNOWN_CONSTS: [(f64, &str, usize); 16] = [
+const KNOWN_CONSTS: [(f64, &str, usize); 18] = [
(f64::E, "E", 4),
(f64::FRAC_1_PI, "FRAC_1_PI", 4),
(f64::FRAC_1_SQRT_2, "FRAC_1_SQRT_2", 5),
(f64::LN_2, "LN_2", 5),
(f64::LOG10_E, "LOG10_E", 5),
(f64::LOG2_E, "LOG2_E", 5),
+ (f64::LOG2_10, "LOG2_10", 5),
+ (f64::LOG10_2, "LOG10_2", 5),
(f64::PI, "PI", 3),
(f64::SQRT_2, "SQRT_2", 5),
];
declare_lint_pass!(ApproxConstant => [APPROX_CONSTANT]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ApproxConstant {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) {
+impl<'tcx> LateLintPass<'tcx> for ApproxConstant {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
if let ExprKind::Lit(lit) = &e.kind {
check_lit(cx, &lit.node, e);
}
}
}
-fn check_lit(cx: &LateContext<'_, '_>, lit: &LitKind, e: &Expr<'_>) {
+fn check_lit(cx: &LateContext<'_>, lit: &LitKind, e: &Expr<'_>) {
match *lit {
LitKind::Float(s, LitFloatType::Suffixed(fty)) => match fty {
FloatTy::F32 => check_known_consts(cx, e, s, "f32"),
}
}
-fn check_known_consts(cx: &LateContext<'_, '_>, e: &Expr<'_>, s: symbol::Symbol, module: &str) {
+fn check_known_consts(cx: &LateContext<'_>, e: &Expr<'_>, s: symbol::Symbol, module: &str) {
let s = s.as_str();
if s.parse::<f64>().is_ok() {
for &(constant, name, min_digits) in &KNOWN_CONSTS {