| 1 | // Copyright 2021 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // Test for slice to array pointer conversion introduced in go1.17 |
| 6 | // See: https://tip.golang.org/ref/spec#Conversions_from_slice_to_array_pointer |
| 7 | |
| 8 | package main |
| 9 | |
| 10 | func main() { |
| 11 | s := make([]byte, 2, 4) |
| 12 | if s0 := (*[0]byte)(s); s0 == nil { |
| 13 | panic("converted from non-nil slice result in nil array pointer") |
| 14 | } |
| 15 | if s2 := (*[2]byte)(s); &s2[0] != &s[0] { |
| 16 | panic("the converted array is not slice underlying array") |
| 17 | } |
| 18 | wantPanic( |
| 19 | func() { |
| 20 | _ = (*[4]byte)(s) // panics: len([4]byte) > len(s) |
| 21 | }, |
| 22 | "runtime error: array length is greater than slice length", |
| 23 | ) |
| 24 | |
| 25 | var t []string |
| 26 | if t0 := (*[0]string)(t); t0 != nil { |
| 27 | panic("nil slice converted to *[0]byte should be nil") |
| 28 | } |
| 29 | wantPanic( |
| 30 | func() { |
| 31 | _ = (*[1]string)(t) // panics: len([1]string) > len(t) |
| 32 | }, |
| 33 | "runtime error: array length is greater than slice length", |
| 34 | ) |
| 35 | |
| 36 | f() |
| 37 | } |
| 38 | |
| 39 | type arr [2]int |
| 40 | |
| 41 | func f() { |
| 42 | s := []int{1, 2, 3, 4} |
| 43 | _ = *(*arr)(s) |
| 44 | } |
| 45 | |
| 46 | func wantPanic(fn func(), s string) { |
| 47 | defer func() { |
| 48 | err := recover() |
| 49 | if err == nil { |
| 50 | panic("expected panic") |
| 51 | } |
| 52 | if got := err.(error).Error(); got != s { |
| 53 | panic("expected panic " + s + " got " + got) |
| 54 | } |
| 55 | }() |
| 56 | fn() |
| 57 | } |
| 58 |
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