use crate::consts::{constant_simple, Constant};
-use crate::utils::{match_def_path, paths, span_lint};
-use rustc::hir::*;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::{declare_tool_lint, lint_array};
+use crate::utils::{match_def_path, match_trait_method, paths, span_lint};
+use if_chain::if_chain;
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
use std::cmp::Ordering;
declare_clippy_lint! {
/// ```ignore
/// min(0, max(100, x))
/// ```
+ /// or
+ /// ```ignore
+ /// x.max(100).min(0)
+ /// ```
/// 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,
"`min(_, max(_, _))` (or vice versa) with bounds clamping the result to a constant"
}
-pub struct MinMaxPass;
-
-impl LintPass for MinMaxPass {
- fn get_lints(&self) -> LintArray {
- lint_array!(MIN_MAX)
- }
-
- fn name(&self) -> &'static str {
- "MinMax"
- }
-}
+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) {
+impl<'tcx> LateLintPass<'tcx> for MinMaxPass {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let Some((outer_max, outer_c, oe)) = min_max(cx, expr) {
if let Some((inner_max, inner_c, ie)) = min_max(cx, oe) {
if outer_max == inner_max {
}
match (
outer_max,
- Constant::partial_cmp(cx.tcx, cx.tables.expr_ty(ie), &outer_c, &inner_c),
+ Constant::partial_cmp(cx.tcx, cx.typeck_results().expr_ty(ie), &outer_c, &inner_c),
) {
(_, None) | (MinMax::Max, Some(Ordering::Less)) | (MinMax::Min, Some(Ordering::Greater)) => (),
_ => {
cx,
MIN_MAX,
expr.span,
- "this min/max combination leads to constant result",
+ "this `min`/`max` combination leads to constant result",
);
},
}
}
}
-#[derive(PartialEq, Eq, Debug)]
+#[derive(PartialEq, Eq, Debug, Clone, Copy)]
enum MinMax {
Min,
Max,
}
-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_def(qpath, path.hir_id).opt_def_id().and_then(|def_id| {
- if match_def_path(cx.tcx, def_id, &paths::CMP_MIN) {
- fetch_const(cx, args, MinMax::Min)
- } else if match_def_path(cx.tcx, def_id, &paths::CMP_MAX) {
- fetch_const(cx, args, MinMax::Max)
+fn min_max<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<(MinMax, Constant, &'a Expr<'a>)> {
+ match expr.kind {
+ ExprKind::Call(ref path, ref args) => {
+ if let ExprKind::Path(ref qpath) = path.kind {
+ cx.typeck_results()
+ .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, def_id, &paths::CMP_MAX) {
+ fetch_const(cx, args, MinMax::Max)
+ } else {
+ None
+ }
+ })
+ } else {
+ None
+ }
+ },
+ ExprKind::MethodCall(ref path, _, ref args, _) => {
+ if_chain! {
+ if let [obj, _] = args;
+ if cx.typeck_results().expr_ty(obj).is_floating_point() || match_trait_method(cx, expr, &paths::ORD);
+ then {
+ if path.ident.name == sym!(max) {
+ fetch_const(cx, args, MinMax::Max)
+ } else if path.ident.name == sym!(min) {
+ fetch_const(cx, args, MinMax::Min)
+ } else {
+ None
+ }
} else {
None
}
- })
- } else {
- None
- }
- } else {
- None
+ }
+ },
+ _ => 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<'a>], m: MinMax) -> Option<(MinMax, Constant, &'a Expr<'a>)> {
if args.len() != 2 {
return None;
}
- if let Some(c) = constant_simple(cx, cx.tables, &args[0]) {
- if constant_simple(cx, cx.tables, &args[1]).is_none() {
- // otherwise ignore
- Some((m, c, &args[1]))
- } else {
- None
- }
- } else if let Some(c) = constant_simple(cx, cx.tables, &args[1]) {
- Some((m, c, &args[0]))
- } else {
- None
- }
+ constant_simple(cx, cx.typeck_results(), &args[0]).map_or_else(
+ || constant_simple(cx, cx.typeck_results(), &args[1]).map(|c| (m, c, &args[0])),
+ |c| {
+ if constant_simple(cx, cx.typeck_results(), &args[1]).is_none() {
+ // otherwise ignore
+ Some((m, c, &args[1]))
+ } else {
+ None
+ }
+ },
+ )
}