use crate::consts::{constant_simple, Constant};
-use rustc::lint::*;
+use crate::utils::{match_def_path, paths, span_lint};
use rustc::hir::*;
-use std::cmp::{Ordering, PartialOrd};
-use crate::utils::{match_def_path, opt_def_id, paths, span_lint};
+use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use rustc::{declare_lint_pass, declare_tool_lint};
+use std::cmp::Ordering;
-/// **What it does:** Checks for expressions where `std::cmp::min` and `max` are
-/// used to clamp values, but switched so that the result is constant.
-///
-/// **Why is this bad?** This is in all probability not the intended outcome. At
-/// the least it hurts readability of the code.
-///
-/// **Known problems:** None
-///
-/// **Example:**
-/// ```rust
-/// min(0, max(100, x))
-/// ```
-/// It will always be equal to `0`. Probably the author meant to clamp the value
-/// between 0 and 100, but has erroneously swapped `min` and `max`.
declare_clippy_lint! {
+ /// **What it does:** Checks for expressions where `std::cmp::min` and `max` are
+ /// used to clamp values, but switched so that the result is constant.
+ ///
+ /// **Why is this bad?** This is in all probability not the intended outcome. At
+ /// the least it hurts readability of the code.
+ ///
+ /// **Known problems:** None
+ ///
+ /// **Example:**
+ /// ```ignore
+ /// min(0, max(100, x))
+ /// ```
+ /// It will always be equal to `0`. Probably the author meant to clamp the value
+ /// between 0 and 100, but has erroneously swapped `min` and `max`.
pub MIN_MAX,
correctness,
"`min(_, max(_, _))` (or vice versa) with bounds clamping the result to a constant"
}
-#[allow(missing_copy_implementations)]
-pub struct MinMaxPass;
-
-impl LintPass for MinMaxPass {
- fn get_lints(&self) -> LintArray {
- lint_array!(MIN_MAX)
- }
-}
+declare_lint_pass!(MinMaxPass => [MIN_MAX]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MinMaxPass {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
if let Some((outer_max, outer_c, oe)) = min_max(cx, expr) {
- if let Some((inner_max, inner_c, _)) = min_max(cx, oe) {
+ if let Some((inner_max, inner_c, ie)) = min_max(cx, oe) {
if outer_max == inner_max {
return;
}
- match (outer_max, outer_c.partial_cmp(&inner_c)) {
+ match (
+ outer_max,
+ Constant::partial_cmp(cx.tcx, cx.tables.expr_ty(ie), &outer_c, &inner_c),
+ ) {
(_, None) | (MinMax::Max, Some(Ordering::Less)) | (MinMax::Min, Some(Ordering::Greater)) => (),
_ => {
- span_lint(cx, MIN_MAX, expr.span, "this min/max combination leads to constant result");
+ span_lint(
+ cx,
+ MIN_MAX,
+ expr.span,
+ "this min/max combination leads to constant result",
+ );
},
}
}
Max,
}
-fn min_max<'a>(cx: &LateContext, expr: &'a Expr) -> Option<(MinMax, Constant, &'a Expr)> {
- if let ExprCall(ref path, ref args) = expr.node {
- if let ExprPath(ref qpath) = path.node {
- opt_def_id(cx.tables.qpath_def(qpath, path.hir_id)).and_then(|def_id| {
- if match_def_path(cx.tcx, def_id, &paths::CMP_MIN) {
+fn min_max<'a>(cx: &LateContext<'_, '_>, expr: &'a Expr) -> Option<(MinMax, Constant, &'a Expr)> {
+ if let ExprKind::Call(ref path, ref args) = expr.node {
+ if let ExprKind::Path(ref qpath) = path.node {
+ cx.tables.qpath_res(qpath, path.hir_id).opt_def_id().and_then(|def_id| {
+ if match_def_path(cx, def_id, &paths::CMP_MIN) {
fetch_const(cx, args, MinMax::Min)
- } else if match_def_path(cx.tcx, def_id, &paths::CMP_MAX) {
+ } else if match_def_path(cx, def_id, &paths::CMP_MAX) {
fetch_const(cx, args, MinMax::Max)
} else {
None
}
}
-fn fetch_const<'a>(cx: &LateContext, args: &'a [Expr], m: MinMax) -> Option<(MinMax, Constant, &'a Expr)> {
+fn fetch_const<'a>(cx: &LateContext<'_, '_>, args: &'a [Expr], m: MinMax) -> Option<(MinMax, Constant, &'a Expr)> {
if args.len() != 2 {
return None;
}