diff options
author | Russ Cox <rsc@golang.org> | 2010-09-13 15:42:47 -0400 |
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committer | Russ Cox <rsc@golang.org> | 2010-09-13 15:42:47 -0400 |
commit | 23bd214aeeb660f26642cc81153edfa87683a289 (patch) | |
tree | 45c59deebd738324c04892b65eea3c8a86a71672 /test/cmp6.go | |
parent | c3900387db5f44eeb97170fd613a0c263ff6185d (diff) | |
download | go-23bd214aeeb660f26642cc81153edfa87683a289.tar.gz go-23bd214aeeb660f26642cc81153edfa87683a289.zip |
gc: implement new comparison rule
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
Diffstat (limited to 'test/cmp6.go')
-rw-r--r-- | test/cmp6.go | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/test/cmp6.go b/test/cmp6.go new file mode 100644 index 0000000000..981a859531 --- /dev/null +++ b/test/cmp6.go @@ -0,0 +1,42 @@ +// 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) +} |