compress/lzw: compress/decompress corrupts data #11142

package main

import (
    "bytes"
    "compress/lzw"
    "fmt"
    "io/ioutil"
)

func main() {
    uncomp := []byte("a")
    buf := new(bytes.Buffer)
    w := lzw.NewWriter(buf, lzw.LSB, 2)
    _, err := w.Write(uncomp)
    if err != nil {
        panic(err)
    }
    if err := w.Close(); err != nil {
        panic(err)
    }
    r1 := lzw.NewReader(buf, lzw.LSB, 2)
    uncomp1, err := ioutil.ReadAll(r1)
    if err != nil {
        panic(err)
    }
    if !bytes.Equal(uncomp, uncomp1) {
        fmt.Printf("data0: %q\n", uncomp)
        fmt.Printf("data0: %q\n", uncomp1)
        panic("data differs")
    }
}