go/test/strcopy.go

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// run
// Copyright 2018 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 string([]byte(string)) makes a copy and doesn't reduce to
// nothing. (Issue 25834)
package main
import (
"reflect"
"unsafe"
)
func main() {
var (
buf = make([]byte, 2<<10)
large = string(buf)
sub = large[10:12]
subcopy = string([]byte(sub))
subh = *(*reflect.StringHeader)(unsafe.Pointer(&sub))
subcopyh = *(*reflect.StringHeader)(unsafe.Pointer(&subcopy))
)
if subh.Data == subcopyh.Data {
panic("sub and subcopy have the same underlying array")
}
}