mirror of
https://github.com/golang/go.git
synced 2025-11-04 10:40:57 +00:00
502958ffa6
Array values are comparable if values of the array element type are comparable. Fixes #6526. LGTM=khr R=rsc, bradfitz, khr CC=golang-codereviews https://golang.org/cl/58580043
86 lines
2.1 KiB
Go
86 lines
2.1 KiB
Go
// errorcheck
|
|
|
|
// Copyright 2010 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.
|
|
|
|
// Verify that incorrect comparisons are detected.
|
|
// Does not compile.
|
|
|
|
package main
|
|
|
|
func use(bool) {}
|
|
|
|
type T1 *int
|
|
type T2 *int
|
|
|
|
type T3 struct{ z []int }
|
|
|
|
var t3 T3
|
|
|
|
type T4 struct {
|
|
_ []int
|
|
a float64
|
|
}
|
|
|
|
var t4 T4
|
|
|
|
func main() {
|
|
// Arguments to comparison must be
|
|
// assignable one to the other (or vice versa)
|
|
// so chan int can be compared against
|
|
// directional channels but channel of different
|
|
// direction cannot be compared against each other.
|
|
var c1 chan<- int
|
|
var c2 <-chan int
|
|
var c3 chan int
|
|
|
|
use(c1 == c2) // ERROR "invalid operation|incompatible"
|
|
use(c2 == c1) // ERROR "invalid operation|incompatible"
|
|
use(c1 == c3)
|
|
use(c2 == c2)
|
|
use(c3 == c1)
|
|
use(c3 == c2)
|
|
|
|
// Same applies to named types.
|
|
var p1 T1
|
|
var p2 T2
|
|
var p3 *int
|
|
|
|
use(p1 == p2) // ERROR "invalid operation|incompatible"
|
|
use(p2 == p1) // ERROR "invalid operation|incompatible"
|
|
use(p1 == p3)
|
|
use(p2 == p2)
|
|
use(p3 == p1)
|
|
use(p3 == p2)
|
|
|
|
// Arrays are comparable if and only if their element type is comparable.
|
|
var a1 [1]int
|
|
var a2 [1]func()
|
|
var a3 [0]func()
|
|
use(a1 == a1)
|
|
use(a2 == a2) // ERROR "invalid operation|invalid comparison"
|
|
use(a3 == a3) // ERROR "invalid operation|invalid comparison"
|
|
|
|
// Comparison of structs should have a good message
|
|
use(t3 == t3) // ERROR "struct|expected"
|
|
use(t4 == t4) // ERROR "cannot be compared|non-comparable"
|
|
|
|
// Slices, functions, and maps too.
|
|
var x []int
|
|
var f func()
|
|
var m map[int]int
|
|
use(x == x) // ERROR "slice can only be compared to nil"
|
|
use(f == f) // ERROR "func can only be compared to nil"
|
|
use(m == m) // ERROR "map can only be compared to nil"
|
|
|
|
// Comparison with interface that cannot return true
|
|
// (would panic).
|
|
var i interface{}
|
|
use(i == x) // ERROR "invalid operation"
|
|
use(x == i) // ERROR "invalid operation"
|
|
use(i == f) // ERROR "invalid operation"
|
|
use(f == i) // ERROR "invalid operation"
|
|
use(i == m) // ERROR "invalid operation"
|
|
use(m == i) // ERROR "invalid operation"
|
|
}
|