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Merge pull request #454 from apasel422/issue-446

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Match `min` and `max` functions using `DefId`
This commit is contained in:
Manish Goregaokar 2015-11-11 21:48:33 +05:30
commit 9881f1b49d
2 changed files with 13 additions and 7 deletions
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16
src/minmax.rs
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@ -5,7 +5,7 @@ use std::cmp::PartialOrd;
use std::cmp::Ordering::*; use std::cmp::Ordering::*;
use consts::{Constant, constant_simple}; use consts::{Constant, constant_simple};
use utils::{match_path, span_lint}; use utils::{match_def_path, span_lint};
use self::MinMax::{Min, Max}; use self::MinMax::{Min, Max};
declare_lint!(pub MIN_MAX, Warn, declare_lint!(pub MIN_MAX, Warn,
@ -23,8 +23,8 @@ impl LintPass for MinMaxPass {
impl LateLintPass for MinMaxPass { impl LateLintPass for MinMaxPass {
fn check_expr(&mut self, cx: &LateContext, expr: &Expr) { fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
if let Some((outer_max, outer_c, oe)) = min_max(expr) { if let Some((outer_max, outer_c, oe)) = min_max(cx, expr) {
if let Some((inner_max, inner_c, _)) = min_max(oe) { if let Some((inner_max, inner_c, _)) = min_max(cx, oe) {
if outer_max == inner_max { return; } if outer_max == inner_max { return; }
match (outer_max, outer_c.partial_cmp(&inner_c)) { match (outer_max, outer_c.partial_cmp(&inner_c)) {
(_, None) | (Max, Some(Less)) | (Min, Some(Greater)) => (), (_, None) | (Max, Some(Less)) | (Min, Some(Greater)) => (),
@ -44,13 +44,15 @@ enum MinMax {
Max, Max,
} }
fn min_max(expr: &Expr) -> Option<(MinMax, Constant, &Expr)> { 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 ExprCall(ref path, ref args) = expr.node {
if let ExprPath(None, ref path) = path.node { if let ExprPath(None, _) = path.node {
if match_path(path, &["std", "cmp", "min"]) { let def_id = cx.tcx.def_map.borrow()[&path.id].def_id();
if match_def_path(cx, def_id, &["core", "cmp", "min"]) {
fetch_const(args, Min) fetch_const(args, Min)
} else { } else {
if match_path(path, &["std", "cmp", "max"]) { if match_def_path(cx, def_id, &["core", "cmp", "max"]) {
fetch_const(args, Max) fetch_const(args, Max)
} else { } else {
None None

4
tests/compile-fail/min_max.rs
View File

@ -4,6 +4,8 @@
#![deny(clippy)] #![deny(clippy)]
use std::cmp::{min, max}; use std::cmp::{min, max};
use std::cmp::min as my_min;
use std::cmp::max as my_max;
const LARGE : usize = 3; const LARGE : usize = 3;
@ -15,6 +17,8 @@ fn main() {
max(min(x, 1), 3); //~ERROR this min/max combination leads to constant result max(min(x, 1), 3); //~ERROR this min/max combination leads to constant result
max(3, min(x, 1)); //~ERROR this min/max combination leads to constant result max(3, min(x, 1)); //~ERROR this min/max combination leads to constant result
my_max(3, my_min(x, 1)); //~ERROR this min/max combination leads to constant result
min(3, max(1, x)); // ok, could be 1, 2 or 3 depending on x min(3, max(1, x)); // ok, could be 1, 2 or 3 depending on x
min(1, max(LARGE, x)); // no error, we don't lookup consts here min(1, max(LARGE, x)); // no error, we don't lookup consts here