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ceffdc8545
The conversion T(x) is implemented as *(*T)(x). Accordingly, runtime panic messages for (*T)(x) are made more general. Fixes #46505. Change-Id: I76317c0878b6a5908299506d392eed50d7ef6523 Reviewed-on: https://go-review.googlesource.com/c/go/+/430415 Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Jenny Rakoczy <jenny@golang.org> TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Matthew Dempsky <mdempsky@google.com> Reviewed-by: Keith Randall <khr@golang.org>
108 lines
2.1 KiB
Go
108 lines
2.1 KiB
Go
// run
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// Copyright 2020 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test conversion from slice to array pointer.
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package main
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func wantPanic(fn func(), s string) {
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defer func() {
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err := recover()
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if err == nil {
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panic("expected panic")
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}
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if got := err.(error).Error(); got != s {
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panic("expected panic " + s + " got " + got)
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}
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}()
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fn()
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}
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func main() {
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s := make([]byte, 8, 10)
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for i := range s {
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s[i] = byte(i)
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}
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if p := (*[8]byte)(s); &p[0] != &s[0] {
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panic("*[8]byte conversion failed")
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}
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if [8]byte(s) != *(*[8]byte)(s) {
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panic("[8]byte conversion failed")
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}
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wantPanic(
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func() {
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_ = (*[9]byte)(s)
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},
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"runtime error: cannot convert slice with length 8 to array or pointer to array with length 9",
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)
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wantPanic(
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func() {
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_ = [9]byte(s)
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},
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"runtime error: cannot convert slice with length 8 to array or pointer to array with length 9",
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)
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var n []byte
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if p := (*[0]byte)(n); p != nil {
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panic("nil slice converted to *[0]byte should be nil")
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}
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_ = [0]byte(n)
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z := make([]byte, 0)
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if p := (*[0]byte)(z); p == nil {
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panic("empty slice converted to *[0]byte should be non-nil")
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}
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_ = [0]byte(z)
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var p *[]byte
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wantPanic(
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func() {
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_ = [0]byte(*p) // evaluating *p should still panic
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},
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"runtime error: invalid memory address or nil pointer dereference",
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)
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// Test with named types
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type Slice []int
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type Int4 [4]int
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type PInt4 *[4]int
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ii := make(Slice, 4)
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if p := (*Int4)(ii); &p[0] != &ii[0] {
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panic("*Int4 conversion failed")
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}
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if p := PInt4(ii); &p[0] != &ii[0] {
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panic("PInt4 conversion failed")
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}
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}
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// test static variable conversion
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var (
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ss = make([]string, 10)
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s5 = (*[5]string)(ss)
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s10 = (*[10]string)(ss)
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ns []string
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ns0 = (*[0]string)(ns)
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zs = make([]string, 0)
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zs0 = (*[0]string)(zs)
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)
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func init() {
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if &ss[0] != &s5[0] {
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panic("s5 conversion failed")
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}
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if &ss[0] != &s10[0] {
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panic("s5 conversion failed")
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}
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if ns0 != nil {
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panic("ns0 should be nil")
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}
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if zs0 == nil {
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panic("zs0 should not be nil")
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}
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}
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