// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file contains tests for the useless-assignment checker.
package testdata
import "math/rand"
type ST struct {
x int
l []int
}
func (s *ST) SetX(x int, ch chan int) {
// Accidental self-assignment; it should be "s.x = x"
// want "self-assignment of x to x"
// Another mistake
// want "self-assignment of s.x to s.x"
// want "self-assignment of s.l.0. to s.l.0."
// Bail on any potential side effects to avoid false positives
s.l[num()] = s.l[num()]
rng := rand.New(rand.NewSource(0))
s.l[rng.Intn(len(s.l))] = s.l[rng.Intn(len(s.l))]
s.l[<-ch] = s.l[<-ch]
}
func num() int { return 2 }
func Index() {
s := []int{1}
// want "self-assignment"
var a [5]int
// want "self-assignment"
pa := &[2]int{1, 2}
// want "self-assignment"
var pss *struct { // report self assignment despite nil dereference
s []int
}
// want "self-assignment"
m := map[int]string{1: "a"}
m[0] = m[0] // bail on map self-assignments due to side effects
m[1] = m[1] // not modeling what elements must be in the map
(m[2]) = (m[2]) // even with parens
type Map map[string]bool
named := make(Map)
named["s"] = named["s"] // even on named maps.
var psm *struct {
m map[string]int
}
psm.m["key"] = psm.m["key"] // handles dereferences
}