| // run | |
| // Copyright 2023 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. | |
| package main | |
| import ( | |
| "strings" | |
| "unsafe" | |
| ) | |
| func shift[T any]() int64 { | |
| return 1 << unsafe.Sizeof(*new(T)) | |
| } | |
| func div[T any]() uintptr { | |
| return 1 / unsafe.Sizeof(*new(T)) | |
| } | |
| func add[T any]() int64 { | |
| return 1<<63 - 1 + int64(unsafe.Sizeof(*new(T))) | |
| } | |
| func main() { | |
| shift[[62]byte]() | |
| shift[[63]byte]() | |
| shift[[64]byte]() | |
| shift[[100]byte]() | |
| shift[[1e6]byte]() | |
| add[[1]byte]() | |
| shouldPanic("divide by zero", func() { div[[0]byte]() }) | |
| } | |
| func shouldPanic(str string, f func()) { | |
| defer func() { | |
| err := recover() | |
| if err == nil { | |
| panic("did not panic") | |
| } | |
| s := err.(error).Error() | |
| if !strings.Contains(s, str) { | |
| panic("got panic " + s + ", want " + str) | |
| } | |
| }() | |
| f() | |
| } |