-use clippy_utils::diagnostics::span_lint;
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::{meets_msrv, msrvs};
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_semver::RustcVersion;
+use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::symbol;
use std::f64::consts as f64;
/// let x = 3.14;
/// let y = 1_f64 / x;
/// ```
- /// Use predefined constants instead:
+ /// Use instead:
/// ```rust
/// let x = std::f32::consts::PI;
/// let y = std::f64::consts::FRAC_1_PI;
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub APPROX_CONSTANT,
correctness,
"the approximate of a known float constant (in `std::fXX::consts`)"
}
-// Tuples are of the form (constant, name, min_digits)
-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::FRAC_2_PI, "FRAC_2_PI", 5),
- (f64::FRAC_2_SQRT_PI, "FRAC_2_SQRT_PI", 5),
- (f64::FRAC_PI_2, "FRAC_PI_2", 5),
- (f64::FRAC_PI_3, "FRAC_PI_3", 5),
- (f64::FRAC_PI_4, "FRAC_PI_4", 5),
- (f64::FRAC_PI_6, "FRAC_PI_6", 5),
- (f64::FRAC_PI_8, "FRAC_PI_8", 5),
- (f64::LN_10, "LN_10", 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),
+// Tuples are of the form (constant, name, min_digits, msrv)
+const KNOWN_CONSTS: [(f64, &str, usize, Option<RustcVersion>); 19] = [
+ (f64::E, "E", 4, None),
+ (f64::FRAC_1_PI, "FRAC_1_PI", 4, None),
+ (f64::FRAC_1_SQRT_2, "FRAC_1_SQRT_2", 5, None),
+ (f64::FRAC_2_PI, "FRAC_2_PI", 5, None),
+ (f64::FRAC_2_SQRT_PI, "FRAC_2_SQRT_PI", 5, None),
+ (f64::FRAC_PI_2, "FRAC_PI_2", 5, None),
+ (f64::FRAC_PI_3, "FRAC_PI_3", 5, None),
+ (f64::FRAC_PI_4, "FRAC_PI_4", 5, None),
+ (f64::FRAC_PI_6, "FRAC_PI_6", 5, None),
+ (f64::FRAC_PI_8, "FRAC_PI_8", 5, None),
+ (f64::LN_2, "LN_2", 5, None),
+ (f64::LN_10, "LN_10", 5, None),
+ (f64::LOG2_10, "LOG2_10", 5, Some(msrvs::LOG2_10)),
+ (f64::LOG2_E, "LOG2_E", 5, None),
+ (f64::LOG10_2, "LOG10_2", 5, Some(msrvs::LOG10_2)),
+ (f64::LOG10_E, "LOG10_E", 5, None),
+ (f64::PI, "PI", 3, None),
+ (f64::SQRT_2, "SQRT_2", 5, None),
+ (f64::TAU, "TAU", 3, Some(msrvs::TAU)),
];
-declare_lint_pass!(ApproxConstant => [APPROX_CONSTANT]);
+pub struct ApproxConstant {
+ msrv: Option<RustcVersion>,
+}
-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);
+impl ApproxConstant {
+ #[must_use]
+ pub fn new(msrv: Option<RustcVersion>) -> Self {
+ Self { msrv }
+ }
+
+ fn check_lit(&self, cx: &LateContext<'_>, lit: &LitKind, e: &Expr<'_>) {
+ match *lit {
+ LitKind::Float(s, LitFloatType::Suffixed(fty)) => match fty {
+ FloatTy::F32 => self.check_known_consts(cx, e, s, "f32"),
+ FloatTy::F64 => self.check_known_consts(cx, e, s, "f64"),
+ },
+ LitKind::Float(s, LitFloatType::Unsuffixed) => self.check_known_consts(cx, e, s, "f{32, 64}"),
+ _ => (),
}
}
-}
-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"),
- FloatTy::F64 => check_known_consts(cx, e, s, "f64"),
- },
- LitKind::Float(s, LitFloatType::Unsuffixed) => check_known_consts(cx, e, s, "f{32, 64}"),
- _ => (),
+ fn check_known_consts(&self, 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, msrv) in &KNOWN_CONSTS {
+ if is_approx_const(constant, s, min_digits) && msrv.map_or(true, |msrv| meets_msrv(self.msrv, msrv)) {
+ span_lint_and_help(
+ cx,
+ APPROX_CONSTANT,
+ e.span,
+ &format!("approximate value of `{module}::consts::{}` found", &name),
+ None,
+ "consider using the constant directly",
+ );
+ return;
+ }
+ }
+ }
}
}
-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 {
- if is_approx_const(constant, &s, min_digits) {
- span_lint(
- cx,
- APPROX_CONSTANT,
- e.span,
- &format!(
- "approximate value of `{}::consts::{}` found. \
- Consider using it directly",
- module, &name
- ),
- );
- return;
- }
+impl_lint_pass!(ApproxConstant => [APPROX_CONSTANT]);
+
+impl<'tcx> LateLintPass<'tcx> for ApproxConstant {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
+ if let ExprKind::Lit(lit) = &e.kind {
+ self.check_lit(cx, &lit.node, e);
}
}
+
+ extract_msrv_attr!(LateContext);
}
/// Returns `false` if the number of significant figures in `value` are
// The value is a truncated constant
true
} else {
- let round_const = format!("{:.*}", value.len() - 2, constant);
+ let round_const = format!("{constant:.*}", value.len() - 2);
value == round_const
}
}
projects / rust.git / blobdiff