diff --git a/clippy_lints/src/minmax.rs b/clippy_lints/src/minmax.rs index dae39aaf5e21..004dd50a31be 100644 --- a/clippy_lints/src/minmax.rs +++ b/clippy_lints/src/minmax.rs @@ -1,5 +1,6 @@ use crate::consts::{constant_simple, Constant}; -use crate::utils::{match_def_path, paths, span_lint}; +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}; @@ -18,6 +19,10 @@ 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, @@ -60,25 +65,43 @@ enum MinMax { } fn min_max<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<(MinMax, Constant, &'a Expr<'a>)> { - if let ExprKind::Call(ref path, ref args) = expr.kind { - 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) { + 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.as_str() == sym!(max).as_str() { fetch_const(cx, args, MinMax::Max) + } else if path.ident.as_str() == sym!(min).as_str() { + fetch_const(cx, args, MinMax::Min) } else { None } - }) - } else { - None - } - } else { - None + } else { + None + } + } + }, + _ => None, } } diff --git a/tests/ui/min_max.rs b/tests/ui/min_max.rs index 8307d4b3019f..f7ed72a11cf6 100644 --- a/tests/ui/min_max.rs +++ b/tests/ui/min_max.rs @@ -6,6 +6,18 @@ use std::cmp::{max, min}; const LARGE: usize = 3; +struct NotOrd(u64); + +impl NotOrd { + fn min(self, x: u64) -> NotOrd { + NotOrd(x) + } + + fn max(self, x: u64) -> NotOrd { + NotOrd(x) + } +} + fn main() { let x; x = 2usize; @@ -30,4 +42,24 @@ fn main() { max(min(s, "Apple"), "Zoo"); max("Apple", min(s, "Zoo")); // ok + + let f = 3f32; + x.min(1).max(3); + x.max(3).min(1); + f.max(3f32).min(1f32); + + x.max(1).min(3); // ok + x.min(3).max(1); // ok + f.min(3f32).max(1f32); // ok + + max(x.min(1), 3); + min(x.max(1), 3); // ok + + s.max("Zoo").min("Apple"); + s.min("Apple").max("Zoo"); + + s.min("Zoo").max("Apple"); // ok + + let not_ord = NotOrd(1); + not_ord.min(1).max(3); // ok } diff --git a/tests/ui/min_max.stderr b/tests/ui/min_max.stderr index b552c137f7c7..9f8e26fa406f 100644 --- a/tests/ui/min_max.stderr +++ b/tests/ui/min_max.stderr @@ -1,5 +1,5 @@ error: this `min`/`max` combination leads to constant result - --> $DIR/min_max.rs:12:5 + --> $DIR/min_max.rs:24:5 | LL | min(1, max(3, x)); | ^^^^^^^^^^^^^^^^^ @@ -7,40 +7,76 @@ LL | min(1, max(3, x)); = note: `-D clippy::min-max` implied by `-D warnings` error: this `min`/`max` combination leads to constant result - --> $DIR/min_max.rs:13:5 + --> $DIR/min_max.rs:25:5 | LL | min(max(3, x), 1); | ^^^^^^^^^^^^^^^^^ error: this `min`/`max` combination leads to constant result - --> $DIR/min_max.rs:14:5 + --> $DIR/min_max.rs:26:5 | LL | max(min(x, 1), 3); | ^^^^^^^^^^^^^^^^^ error: this `min`/`max` combination leads to constant result - --> $DIR/min_max.rs:15:5 + --> $DIR/min_max.rs:27:5 | LL | max(3, min(x, 1)); | ^^^^^^^^^^^^^^^^^ error: this `min`/`max` combination leads to constant result - --> $DIR/min_max.rs:17:5 + --> $DIR/min_max.rs:29:5 | LL | my_max(3, my_min(x, 1)); | ^^^^^^^^^^^^^^^^^^^^^^^ error: this `min`/`max` combination leads to constant result - --> $DIR/min_max.rs:29:5 + --> $DIR/min_max.rs:41:5 | LL | min("Apple", max("Zoo", s)); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: this `min`/`max` combination leads to constant result - --> $DIR/min_max.rs:30:5 + --> $DIR/min_max.rs:42:5 | LL | max(min(s, "Apple"), "Zoo"); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ -error: aborting due to 7 previous errors +error: this `min`/`max` combination leads to constant result + --> $DIR/min_max.rs:47:5 + | +LL | x.min(1).max(3); + | ^^^^^^^^^^^^^^^ + +error: this `min`/`max` combination leads to constant result + --> $DIR/min_max.rs:48:5 + | +LL | x.max(3).min(1); + | ^^^^^^^^^^^^^^^ + +error: this `min`/`max` combination leads to constant result + --> $DIR/min_max.rs:49:5 + | +LL | f.max(3f32).min(1f32); + | ^^^^^^^^^^^^^^^^^^^^^ + +error: this `min`/`max` combination leads to constant result + --> $DIR/min_max.rs:55:5 + | +LL | max(x.min(1), 3); + | ^^^^^^^^^^^^^^^^ + +error: this `min`/`max` combination leads to constant result + --> $DIR/min_max.rs:58:5 + | +LL | s.max("Zoo").min("Apple"); + | ^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: this `min`/`max` combination leads to constant result + --> $DIR/min_max.rs:59:5 + | +LL | s.min("Apple").max("Zoo"); + | ^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: aborting due to 13 previous errors