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go/test/named1.go
Russ Cox 6e3e380923 allow direct conversion between string and named []byte, []rune
The allowed conversions before and after are:
        type Tstring string
        type Tbyte []byte
        type Trune []rune

        string <-> string  // ok
        string <-> []byte  // ok
        string <-> []rune // ok
        string <-> Tstring // ok
        string <-> Tbyte // was illegal, now ok
        string <-> Trune // was illegal, now ok

        Tstring <-> string  // ok
        Tstring <-> []byte  // ok
        Tstring <-> []rune // ok
        Tstring <-> Tstring // ok
        Tstring <-> Tbyte // was illegal, now ok
        Tstring <-> Trune // was illegal, now ok

Update spec, compiler, tests.  Use in a few packages.

We agreed on this a few months ago but never implemented it.

Fixes #1707.

R=golang-dev, gri, r
CC=golang-dev
https://golang.org/cl/5421057
2011-11-22 12:30:02 -05:00

62 lines
1.1 KiB
Go

// errchk $G -e $D/$F.go
// Copyright 2009 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.
// Test that basic operations on named types are valid
// and preserve the type.
package main
type Bool bool
type Map map[int]int
func (Map) M() {}
type Slice []byte
var slice Slice
func asBool(Bool) {}
func asString(String) {}
type String string
func main() {
var (
b Bool = true
i, j int
c = make(chan int)
m = make(Map)
)
asBool(b)
asBool(!b)
asBool(true)
asBool(*&b)
asBool(Bool(true))
asBool(1 != 2) // ERROR "cannot use.*type ideal bool.*as type Bool"
asBool(i < j) // ERROR "cannot use.*type bool.*as type Bool"
_, b = m[2] // ERROR "cannot .* bool.*type Bool"
var inter interface{}
_, b = inter.(Map) // ERROR "cannot .* bool.*type Bool"
_ = b
var minter interface {
M()
}
_, b = minter.(Map) // ERROR "cannot .* bool.*type Bool"
_ = b
_, bb := <-c
asBool(bb) // ERROR "cannot use.*type bool.*as type Bool"
_, b = <-c // ERROR "cannot .* bool.*type Bool"
_ = b
asString(String(slice)) // ok
}