mirror of
https://github.com/golang/go
synced 2024-11-22 00:54:43 -07:00
23bd214aee
The new comparison rule was added to the spec by changeset: 5605:33abb649cb63 user: Robert Griesemer <gri@golang.org> date: Thu Jun 03 16:55:50 2010 -0700 files: doc/go_spec.html description: go spec: Base comparison compatibility on assignment compatibility. Specifically: - Simplified definition of comparison compatibility and folded into section on comparison operators since it's only used there. This is a small language change/cleanup. As a consequence: - An interface value may now be compared against a non-interface value. - Channels with opposite directions cannot be compared directly anymore (per discussion with rsc). R=rsc, r, iant, ken2 CC=golang-dev https://golang.org/cl/1462041 but never implemented. Fixes #1070. R=ken2 CC=golang-dev https://golang.org/cl/2116047
43 lines
913 B
Go
43 lines
913 B
Go
// errchk $G -e $D/$F.go
|
|
|
|
// 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.
|
|
|
|
package main
|
|
|
|
func use(bool) {}
|
|
|
|
type T1 *int
|
|
type T2 *int
|
|
|
|
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"
|
|
use(c2 == c1) // ERROR "invalid operation"
|
|
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"
|
|
use(p2 == p1) // ERROR "invalid operation"
|
|
use(p1 == p3)
|
|
use(p2 == p2)
|
|
use(p3 == p1)
|
|
use(p3 == p2)
|
|
}
|