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// run
// Copyright 2020 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 conversion from slice to array pointer.
package main
func wantPanic(fn func(), s string) {
defer func() {
err := recover()
if err == nil {
panic("expected panic")
}
if got := err.(error).Error(); got != s {
panic("expected panic " + s + " got " + got)
}
}()
fn()
}
func main() {
s := make([]byte, 8, 10)
for i := range s {
s[i] = byte(i)
}
if p := (*[8]byte)(s); &p[0] != &s[0] {
panic("*[8]byte conversion failed")
}
if [8]byte(s) != *(*[8]byte)(s) {
panic("[8]byte conversion failed")
}
wantPanic(
func() {
_ = (*[9]byte)(s)
},
"runtime error: cannot convert slice with length 8 to array or pointer to array with length 9",
)
wantPanic(
func() {
_ = [9]byte(s)
},
"runtime error: cannot convert slice with length 8 to array or pointer to array with length 9",
)
var n []byte
if p := (*[0]byte)(n); p != nil {
panic("nil slice converted to *[0]byte should be nil")
}
_ = [0]byte(n)
z := make([]byte, 0)
if p := (*[0]byte)(z); p == nil {
panic("empty slice converted to *[0]byte should be non-nil")
}
_ = [0]byte(z)
var p *[]byte
wantPanic(
func() {
_ = [0]byte(*p) // evaluating *p should still panic
},
"runtime error: invalid memory address or nil pointer dereference",
)
// Test with named types
type Slice []int
type Int4 [4]int
type PInt4 *[4]int
ii := make(Slice, 4)
if p := (*Int4)(ii); &p[0] != &ii[0] {
panic("*Int4 conversion failed")
}
if p := PInt4(ii); &p[0] != &ii[0] {
panic("PInt4 conversion failed")
}
}
// test static variable conversion
var (
ss = make([]string, 10)
s5 = (*[5]string)(ss)
s10 = (*[10]string)(ss)
ns []string
ns0 = (*[0]string)(ns)
zs = make([]string, 0)
zs0 = (*[0]string)(zs)
)
func init() {
if &ss[0] != &s5[0] {
panic("s5 conversion failed")
}
if &ss[0] != &s10[0] {
panic("s5 conversion failed")
}
if ns0 != nil {
panic("ns0 should be nil")
}
if zs0 == nil {
panic("zs0 should not be nil")
}
}
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