if err := b.UnreadByte(); err == nil {
		t.Fatal("UnreadByte after ReadByte at EOF: got no error")
	}

	// check not at EOF
	b.WriteString("abcdefghijklmnopqrstuvwxyz")

	// after unsuccessful read
	if n, err := b.Read(nil); n != 0 || err != nil {
		t.Fatalf("Read(nil) = %d,%v; want 0,nil", n, err)
	}
	if err := b.UnreadByte(); err == nil {
		t.Fatal("UnreadByte after Read(nil): got no error")
	}

		// say "pkg syscall (darwin-amd64), type RawSockaddrInet6 struct" is missing.
		// See https://go.dev/issue/4303.
		{
			name: "contexts reconverging after api/next/* update",
			features: []string{
				"A",
				"pkg syscall, type RawSockaddrInet6 struct",
			},
			required: []string{
				"A",

</pre>

<p>
the variable <code>a</code> will be initialized after <code>b</code> but
whether <code>x</code> is initialized before <code>b</code>, between
<code>b</code> and <code>a</code>, or after <code>a</code>, and
thus also the moment at which <code>sideEffect()</code> is called (before
or after <code>x</code> is initialized) is not specified.
</p>

<p>

	extern GoInt64 MyFunction(int arg1, int arg2, GoString arg3);
	extern struct MyFunction2_return MyFunction2(int arg1, int arg2, GoString arg3);

found in the _cgo_export.h generated header, after any preambles
copied from the cgo input files. Functions with multiple
return values are mapped to functions returning a struct.

Not all Go types can be mapped to C types in a useful way.

			{
				Name:     "bar.txt",
				Content:  []byte("bar\n"),
				Modified: time.Date(2012, 3, 8, 16, 59, 12, 0, timeZone(-8*time.Hour)),
				Mode:     0644,
			},
		},
	},
	{
		// created by Go, after we wrote the "optional" data
		// descriptor signatures (which are required by macOS)
		Name: "go-with-datadesc-sig.zip",
		File: []ZipTestFile{
			{
				Name:     "foo.txt",
				Content:  []byte("foo\n"),

# license that can be found in the LICENSE file.

set -e
if [ ! -f make.bash ]; then
	echo 'all.bash must be run from $GOROOT/src' 1>&2
	exit 1
fi
. ./make.bash "$@" --no-banner
bash run.bash --no-rebuild

      description: Breaking the Go 1 compatibility guarantee is a large cost and requires a large benefit.
      placeholder: |
       Yes or No

       If yes, 
        1. Show example code before and after the change.

    validations:
      required: true

  - type: textarea
    id: orthogonality
    attributes:
      label: "Orthogonality: How does this change interact or overlap with existing features?"

// license that can be found in the LICENSE file.

// Package tar implements access to tar archives.
//
// Tape archives (tar) are a file format for storing a sequence of files that
// can be read and written in a streaming manner.
// This package aims to cover most variations of the format,
// including those produced by GNU and BSD tar tools.
package tar

import (
	"errors"
	"fmt"
	"internal/godebug"
	"io/fs"
	"math"
	"path"

	fmt.Println(bytes.Count([]byte("five"), []byte(""))) // before & after each rune
	// Output:
	// 3
	// 5
}

func ExampleCut() {
	show := func(s, sep string) {
		before, after, found := bytes.Cut([]byte(s), []byte(sep))
		fmt.Printf("Cut(%q, %q) = %q, %q, %v\n", s, sep, before, after, found)
	}
	show("Gopher", "Go")
	show("Gopher", "ph")
	show("Gopher", "er")

	for _, tt := range cutTests {
		if before, after, found := Cut([]byte(tt.s), []byte(tt.sep)); string(before) != tt.before || string(after) != tt.after || found != tt.found {
			t.Errorf("Cut(%q, %q) = %q, %q, %v, want %q, %q, %v", tt.s, tt.sep, before, after, found, tt.before, tt.after, tt.found)
		}
	}
}

var cutPrefixTests = []struct {
	s, sep string
	after  string
	found  bool
}{