github.com/hikaru7719/go@v0.0.0-20181025140707-c8b2ac68906a/src/cmd/vet/testdata/bool.go

// Copyright 2014 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 bool checker.

package testdata

import "io"

type T int

func (t T) Foo() int { return int(t) }

type FT func() int

var S []int

func RatherStupidConditions() {
	var f, g func() int
	if f() == 0 || f() == 0 { // OK f might have side effects
	}
	var t T
	_ = t.Foo() == 2 || t.Foo() == 2        // OK Foo might have side effects
	if v, w := f(), g(); v == w || v == w { // ERROR "redundant or: v == w || v == w"
	}
	_ = f == nil || f == nil // ERROR "redundant or: f == nil || f == nil"

	_ = i == byte(1) || i == byte(1) // ERROR "redundant or: i == byte(1) || i == byte(1)"
	_ = i == T(2) || i == T(2)       // ERROR "redundant or: i == T(2) || i == T(2)"
	_ = FT(f) == nil || FT(f) == nil // ERROR "redundant or: FT(f) == nil || FT(f) == nil"

	_ = (func() int)(f) == nil || (func() int)(f) == nil // ERROR "redundant or: (func() int)(f) == nil || (func() int)(f) == nil"
	_ = append(S, 3) == nil || append(S, 3) == nil       // OK append has side effects

	var namedFuncVar FT
	_ = namedFuncVar() == namedFuncVar() // OK still func calls

	var c chan int
	_ = 0 == <-c || 0 == <-c                                  // OK subsequent receives may yield different values
	for i, j := <-c, <-c; i == j || i == j; i, j = <-c, <-c { // ERROR "redundant or: i == j || i == j"
	}

	var i, j, k int
	_ = i+1 == 1 || i+1 == 1         // ERROR "redundant or: i\+1 == 1 || i\+1 == 1"
	_ = i == 1 || j+1 == i || i == 1 // ERROR "redundant or: i == 1 || i == 1"

	_ = i == 1 || i == 1 || f() == 1 // ERROR "redundant or: i == 1 || i == 1"
	_ = i == 1 || f() == 1 || i == 1 // OK f may alter i as a side effect
	_ = f() == 1 || i == 1 || i == 1 // ERROR "redundant or: i == 1 || i == 1"

	// Test partition edge cases
	_ = f() == 1 || i == 1 || i == 1 || j == 1 // ERROR "redundant or: i == 1 || i == 1"
	_ = f() == 1 || j == 1 || i == 1 || i == 1 // ERROR "redundant or: i == 1 || i == 1"
	_ = i == 1 || f() == 1 || i == 1 || i == 1 // ERROR "redundant or: i == 1 || i == 1"
	_ = i == 1 || i == 1 || f() == 1 || i == 1 // ERROR "redundant or: i == 1 || i == 1"
	_ = i == 1 || i == 1 || j == 1 || f() == 1 // ERROR "redundant or: i == 1 || i == 1"
	_ = j == 1 || i == 1 || i == 1 || f() == 1 // ERROR "redundant or: i == 1 || i == 1"
	_ = i == 1 || f() == 1 || f() == 1 || i == 1

	_ = i == 1 || (i == 1 || i == 2)             // ERROR "redundant or: i == 1 || i == 1"
	_ = i == 1 || (f() == 1 || i == 1)           // OK f may alter i as a side effect
	_ = i == 1 || (i == 1 || f() == 1)           // ERROR "redundant or: i == 1 || i == 1"
	_ = i == 1 || (i == 2 || (i == 1 || i == 3)) // ERROR "redundant or: i == 1 || i == 1"

	var a, b bool
	_ = i == 1 || (a || (i == 1 || b)) // ERROR "redundant or: i == 1 || i == 1"

	// Check that all redundant ors are flagged
	_ = j == 0 ||
		i == 1 ||
		f() == 1 ||
		j == 0 || // ERROR "redundant or: j == 0 || j == 0"
		i == 1 || // ERROR "redundant or: i == 1 || i == 1"
		i == 1 || // ERROR "redundant or: i == 1 || i == 1"
		i == 1 ||
		j == 0 ||
		k == 0

	_ = i == 1*2*3 || i == 1*2*3 // ERROR "redundant or: i == 1\*2\*3 || i == 1\*2\*3"

	// These test that redundant, suspect expressions do not trigger multiple errors.
	_ = i != 0 || i != 0 // ERROR "redundant or: i != 0 || i != 0"
	_ = i == 0 && i == 0 // ERROR "redundant and: i == 0 && i == 0"

	// and is dual to or; check the basics and
	// let the or tests pull the rest of the weight.
	_ = 0 != <-c && 0 != <-c         // OK subsequent receives may yield different values
	_ = f() != 0 && f() != 0         // OK f might have side effects
	_ = f != nil && f != nil         // ERROR "redundant and: f != nil && f != nil"
	_ = i != 1 && i != 1 && f() != 1 // ERROR "redundant and: i != 1 && i != 1"
	_ = i != 1 && f() != 1 && i != 1 // OK f may alter i as a side effect
	_ = f() != 1 && i != 1 && i != 1 // ERROR "redundant and: i != 1 && i != 1"
}

func RoyallySuspectConditions() {
	var i, j int

	_ = i == 0 || i == 1 // OK
	_ = i != 0 || i != 1 // ERROR "suspect or: i != 0 || i != 1"
	_ = i != 0 || 1 != i // ERROR "suspect or: i != 0 || 1 != i"
	_ = 0 != i || 1 != i // ERROR "suspect or: 0 != i || 1 != i"
	_ = 0 != i || i != 1 // ERROR "suspect or: 0 != i || i != 1"

	_ = (0 != i) || i != 1 // ERROR "suspect or: 0 != i || i != 1"

	_ = i+3 != 7 || j+5 == 0 || i+3 != 9 // ERROR "suspect or: i\+3 != 7 || i\+3 != 9"

	_ = i != 0 || j == 0 || i != 1 // ERROR "suspect or: i != 0 || i != 1"

	_ = i != 0 || i != 1<<4 // ERROR "suspect or: i != 0 || i != 1<<4"

	_ = i != 0 || j != 0
	_ = 0 != i || 0 != j

	var s string
	_ = s != "one" || s != "the other" // ERROR "suspect or: s != .one. || s != .the other."

	_ = "et" != "alii" || "et" != "cetera"         // ERROR "suspect or: .et. != .alii. || .et. != .cetera."
	_ = "me gustas" != "tu" || "le gustas" != "tu" // OK we could catch this case, but it's not worth the code

	var err error
	_ = err != nil || err != io.EOF // TODO catch this case?

	// Sanity check and.
	_ = i != 0 && i != 1 // OK
	_ = i == 0 && i == 1 // ERROR "suspect and: i == 0 && i == 1"
	_ = i == 0 && 1 == i // ERROR "suspect and: i == 0 && 1 == i"
	_ = 0 == i && 1 == i // ERROR "suspect and: 0 == i && 1 == i"
	_ = 0 == i && i == 1 // ERROR "suspect and: 0 == i && i == 1"
}