slice.go #go #bugreport

README.md

Go playground: https://go.dev/play/p/9HKvgvSWqH3

start=0xc000100000   len=65536  cap=65536  end=0xc000110000   (start == nil) is false, (end == nil) is false, (buf == nil) is false
start=0xc000108000   len=   32  cap=32768  end=0xc000110000   (start == nil) is false, (end == nil) is false, (buf == nil) is false
start=0xc00010fff0   len=   16  cap=   16  end=0xc000110000   (start == nil) is false, (end == nil) is false, (buf == nil) is false
start=0xc00010ffff   len=    1  cap=    1  end=0xc000110000   (start == nil) is false, (end == nil) is false, (buf == nil) is false
start=0xc000100000   len=    0  cap=    0  end=0xc000100000   (start == nil) is false, (end == nil) is false, (buf == nil) is false
start=<nil>          len=    0  cap=    0  end=<nil>          (start == nil) is false, (end == nil) is false, (buf == nil) is true 

Program exited.

Expected start == nil and end == nil to be true.

slice.go

package main

import (
	"fmt"
	"unsafe"
)

func t(buf []byte) {
	start := unsafe.SliceData(buf)
	end := unsafe.Add(unsafe.Pointer(start), cap(buf))
	fmt.Printf(
		"start=%-13v  len=%5v  cap=%5v  end=%-13v  (start == nil) is %-5v, (end == nil) is %-5v, (buf == nil) is %-5v\n",
		start, len(buf), cap(buf), end, start == nil, end == nil, buf == nil,
	)
}

func main() {
	data := make([]byte, 64<<10)
	t(data)
	t(data[32768 : 32768+32])
	t(data[cap(data)-16:])
	t(data[cap(data)-1:])
	t(data[cap(data):])
	t(nil)
}