| // 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() |
| } |