-use consts::{Constant, constant_simple, FloatWidth};
+use crate::consts::{constant_simple, Constant};
use rustc::lint::*;
+use rustc::{declare_lint, lint_array};
+use if_chain::if_chain;
use rustc::hir::*;
-use utils::span_help_and_lint;
+use crate::utils::span_help_and_lint;
-/// `ZeroDivZeroPass` is a pass that checks for a binary expression that consists
-/// `of 0.0/0.0`, which is always `NaN`. It is more clear to replace instances of
-/// `0.0/0.0` with `std::f32::NaN` or `std::f64::NaN`, depending on the precision.
-pub struct ZeroDivZeroPass;
-
-/// **What it does:** This lint checks for `0.0 / 0.0`.
+/// **What it does:** Checks for `0.0 / 0.0`.
///
-/// **Why is this bad?** It's less readable than `std::f32::NAN` or `std::f64::NAN`
+/// **Why is this bad?** It's less readable than `std::f32::NAN` or
+/// `std::f64::NAN`.
///
-/// **Known problems:** None
+/// **Known problems:** None.
///
-/// **Example** `0.0f32 / 0.0`
-declare_lint! {
+/// **Example:**
+/// ```rust
+/// 0.0f32 / 0.0
+/// ```
+declare_clippy_lint! {
pub ZERO_DIVIDED_BY_ZERO,
- Warn,
+ complexity,
"usage of `0.0 / 0.0` to obtain NaN instead of std::f32::NaN or std::f64::NaN"
}
-impl LintPass for ZeroDivZeroPass {
+pub struct Pass;
+
+impl LintPass for Pass {
fn get_lints(&self) -> LintArray {
lint_array!(ZERO_DIVIDED_BY_ZERO)
}
}
-impl LateLintPass for ZeroDivZeroPass {
- fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
+ fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
// check for instances of 0.0/0.0
- if_let_chain! {
- [
- let ExprBinary(ref op, ref left, ref right) = expr.node,
- let BinOp_::BiDiv = op.node,
- // TODO - constant_simple does not fold many operations involving floats.
- // That's probably fine for this lint - it's pretty unlikely that someone would
- // do something like 0.0/(2.0 - 2.0), but it would be nice to warn on that case too.
- let Some(Constant::Float(ref lhs_value, lhs_width)) = constant_simple(left),
- let Some(Constant::Float(ref rhs_value, rhs_width)) = constant_simple(right),
- let Some(0.0) = lhs_value.parse().ok(),
- let Some(0.0) = rhs_value.parse().ok()
- ],
- {
+ if_chain! {
+ if let ExprKind::Binary(ref op, ref left, ref right) = expr.node;
+ if let BinOpKind::Div = op.node;
+ // TODO - constant_simple does not fold many operations involving floats.
+ // That's probably fine for this lint - it's pretty unlikely that someone would
+ // do something like 0.0/(2.0 - 2.0), but it would be nice to warn on that case too.
+ if let Some(lhs_value) = constant_simple(cx, cx.tables, left);
+ if let Some(rhs_value) = constant_simple(cx, cx.tables, right);
+ if Constant::F32(0.0) == lhs_value || Constant::F64(0.0) == lhs_value;
+ if Constant::F32(0.0) == rhs_value || Constant::F64(0.0) == rhs_value;
+ then {
// since we're about to suggest a use of std::f32::NaN or std::f64::NaN,
// match the precision of the literals that are given.
- let float_type = match (lhs_width, rhs_width) {
- (FloatWidth::F64, _)
- | (_, FloatWidth::F64) => "f64",
+ let float_type = match (lhs_value, rhs_value) {
+ (Constant::F64(_), _)
+ | (_, Constant::F64(_)) => "f64",
_ => "f32"
};
- span_help_and_lint(cx, ZERO_DIVIDED_BY_ZERO, expr.span,
+ span_help_and_lint(
+ cx,
+ ZERO_DIVIDED_BY_ZERO,
+ expr.span,
"constant division of 0.0 with 0.0 will always result in NaN",
- &format!("Consider using `std::{}::NAN` if you would like a constant representing NaN", float_type));
+ &format!(
+ "Consider using `std::{}::NAN` if you would like a constant representing NaN",
+ float_type,
+ ),
+ );
}
}
}