-use crate::utils::{numeric_literal, span_lint_and_sugg};
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::numeric_literal;
use if_chain::if_chain;
use rustc_ast::ast::{self, LitFloatType, LitKind};
use rustc_errors::Applicability;
use std::fmt;
declare_clippy_lint! {
- /// **What it does:** Checks for float literals with a precision greater
+ /// ### What it does
+ /// Checks for float literals with a precision greater
/// than that supported by the underlying type.
///
- /// **Why is this bad?** Rust will truncate the literal silently.
- ///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Why is this bad?
+ /// Rust will truncate the literal silently.
///
+ /// ### Example
/// ```rust
- /// // Bad
/// let v: f32 = 0.123_456_789_9;
/// println!("{}", v); // 0.123_456_789
+ /// ```
///
- /// // Good
+ /// Use instead:
+ /// ```rust
/// let v: f64 = 0.123_456_789_9;
/// println!("{}", v); // 0.123_456_789_9
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub EXCESSIVE_PRECISION,
style,
"excessive precision for float literal"
}
declare_clippy_lint! {
- /// **What it does:** Checks for whole number float literals that
+ /// ### What it does
+ /// Checks for whole number float literals that
/// cannot be represented as the underlying type without loss.
///
- /// **Why is this bad?** Rust will silently lose precision during
+ /// ### Why is this bad?
+ /// Rust will silently lose precision during
/// conversion to a float.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
- ///
+ /// ### Example
/// ```rust
- /// // Bad
/// let _: f32 = 16_777_217.0; // 16_777_216.0
+ /// ```
///
- /// // Good
+ /// Use instead:
+ /// ```rust
/// let _: f32 = 16_777_216.0;
/// let _: f64 = 16_777_217.0;
/// ```
+ #[clippy::version = "1.43.0"]
pub LOSSY_FLOAT_LITERAL,
restriction,
"lossy whole number float literals"
impl<'tcx> LateLintPass<'tcx> for FloatLiteral {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
+ let ty = cx.typeck_results().expr_ty(expr);
if_chain! {
- let ty = cx.typeck_results().expr_ty(expr);
if let ty::Float(fty) = *ty.kind();
if let hir::ExprKind::Lit(ref lit) = expr.kind;
if let LitKind::Float(sym, lit_float_ty) = lit.node;
then {
let sym_str = sym.as_str();
- let formatter = FloatFormat::new(&sym_str);
+ let formatter = FloatFormat::new(sym_str);
// Try to bail out if the float is for sure fine.
// If its within the 2 decimal digits of being out of precision we
// check if the parsed representation is the same as the string
// since we'll need the truncated string anyway.
- let digits = count_digits(&sym_str);
+ let digits = count_digits(sym_str);
let max = max_digits(fty);
let type_suffix = match lit_float_ty {
LitFloatType::Suffixed(ast::FloatTy::F32) => Some("f32"),
Applicability::MachineApplicable,
);
}
- } else if digits > max as usize && sym_str != float_str {
+ } else if digits > max as usize && float_str.len() < sym_str.len() {
span_lint_and_sugg(
cx,
EXCESSIVE_PRECISION,
T: fmt::UpperExp + fmt::LowerExp + fmt::Display,
{
match self {
- Self::LowerExp => format!("{:e}", f),
- Self::UpperExp => format!("{:E}", f),
- Self::Normal => format!("{}", f),
+ Self::LowerExp => format!("{f:e}"),
+ Self::UpperExp => format!("{f:E}"),
+ Self::Normal => format!("{f}"),
}
}
}