Merge branch 'macro-use' into HEAD

[rust.git] / clippy_lints / src / zero_div_zero.rs

diff --git a/clippy_lints/src/zero_div_zero.rs b/clippy_lints/src/zero_div_zero.rs
index 8c9f9871228851c961288cb24feadb74a2e336dc..7c8af7880ba22b7ec5f7cdbfcc118f2ad1f32eb6 100644 (file)
--- a/clippy_lints/src/zero_div_zero.rs
+++ b/clippy_lints/src/zero_div_zero.rs
@@ -1,56 +1,67 @@
-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;
 
-/// `Pass` 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 Pass;
-
-/// **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"
 }
 
+pub struct Pass;
+
 impl LintPass for Pass {
     fn get_lints(&self) -> LintArray {
         lint_array!(ZERO_DIVIDED_BY_ZERO)
     }
 }
 
-impl LateLintPass for Pass {
-    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,
+        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.
-            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()
-        ], {
-            // 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",
-                _ => "f32"
-            };
-            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));
-        }}
+            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_value, rhs_value) {
+                    (Constant::F64(_), _)
+                    | (_, Constant::F64(_)) => "f64",
+                    _ => "f32"
+                };
+                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,
+                    ),
+                );
+            }
+        }
     }
 }