}
	return replacementChar
}

// EncodeRune returns the UTF-16 surrogate pair r1, r2 for the given rune.
// If the rune is not a valid Unicode code point or does not need encoding,
// EncodeRune returns U+FFFD, U+FFFD.
func EncodeRune(r rune) (r1, r2 rune) {
	if r < surrSelf || r > maxRune {
		return replacementChar, replacementChar
	}
	r -= surrSelf
	return surr1 + (r>>10)&0x3ff, surr2 + r&0x3ff
}

}

func FuzzRuneRoundTrip(f *testing.F) {
	f.Add(rune(-1))
	f.Add(rune(0xd800))
	f.Add(rune(0xdfff))
	f.Add(rune(unicode.ReplacementChar))
	f.Add(rune(unicode.MaxASCII))
	f.Add(rune(unicode.MaxLatin1))
	f.Add(rune(unicode.MaxRune))
	f.Add(rune(unicode.MaxRune + 1))
	f.Add(rune(-0x80000000))
	f.Add(rune(0x7fffffff))

	f.Fuzz(func(t *testing.T, r1 rune) {
		b := marshalCorpusFile(r1)

	}
}

type decodeTest struct {
	in  []uint16
	out []rune
}

var decodeTests = []decodeTest{
	{[]uint16{1, 2, 3, 4}, []rune{1, 2, 3, 4}},
	{[]uint16{0xffff, 0xd800, 0xdc00, 0xd800, 0xdc01, 0xd808, 0xdf45, 0xdbff, 0xdfff},
		[]rune{0xffff, 0x10000, 0x10001, 0x12345, 0x10ffff}},
	{[]uint16{0xd800, 'a'}, []rune{0xfffd, 'a'}},
	{[]uint16{0xdfff}, []rune{0xfffd}},
}

func TestAllocationsDecode(t *testing.T) {

		return rune(p0&mask2)<<6 | rune(b1&maskx), 2
	}
	b2 := p[2]
	if b2 < locb || hicb < b2 {
		return RuneError, 1
	}
	if sz <= 3 {
		return rune(p0&mask3)<<12 | rune(b1&maskx)<<6 | rune(b2&maskx), 3
	}
	b3 := p[3]
	if b3 < locb || hicb < b3 {
		return RuneError, 1
	}
	return rune(p0&mask4)<<18 | rune(b1&maskx)<<12 | rune(b2&maskx)<<6 | rune(b3&maskx), 4
}

		[]rune{69, 69},
		[]rune{69, 69},
		[]rune{},
		[]uint32{mergeFailed},
		1, 2,
	},
	{
		// append right-first
		[]rune{69, 69},
		[]rune{71, 71},
		[]rune{69, 69, 71, 71},
		[]uint32{1, 2},
		1, 2,
	},
	{
		// append, left-first
		[]rune{71, 71},
		[]rune{69, 69},
		[]rune{69, 69, 71, 71},
		[]uint32{2, 1},
		1, 2,
	},
	{
		// successful interleave
		[]rune{60, 60, 71, 71, 101, 101},

			if len(inst.Next) > 0 {
				break
			}
			instQueue.insert(inst.Out)
			if len(inst.Rune) == 0 {
				onePassRunes[pc] = []rune{}
				inst.Next = []uint32{inst.Out}
				break
			}
			runes := make([]rune, 0)
			if len(inst.Rune) == 1 && syntax.Flags(inst.Arg)&syntax.FoldCase != 0 {
				r0 := inst.Rune[0]
				runes = append(runes, r0, r0)

	0x30, 0x39,
}

var code10 = []rune{ /* [:graph:] */
	0x21, 0x7e,
}

var code11 = []rune{ /* [:lower:] */
	0x61, 0x7a,
}

var code12 = []rune{ /* [:print:] */
	0x20, 0x7e,
}

var code13 = []rune{ /* [:punct:] */
	0x21, 0x2f,
	0x3a, 0x40,
	0x5b, 0x60,
	0x7b, 0x7e,
}

var code14 = []rune{ /* [:space:] */
	0x9, 0xd,
	0x20, 0x20,
}

}

func appendQuotedRuneWith(buf []byte, r rune, quote byte, ASCIIonly, graphicOnly bool) []byte {
	buf = append(buf, quote)
	if !utf8.ValidRune(r) {
		r = utf8.RuneError
	}
	buf = appendEscapedRune(buf, r, quote, ASCIIonly, graphicOnly)
	buf = append(buf, quote)
	return buf
}

func appendEscapedRune(buf []byte, r rune, quote byte, ASCIIonly, graphicOnly bool) []byte {
	if r == rune(quote) || r == '\\' { // always backslashed

	p.numRunes += len(re.Rune)
	if re.Op == OpCharClass && len(re.Rune) == 2 && re.Rune[0] == re.Rune[1] {
		// Single rune.
		if p.maybeConcat(re.Rune[0], p.flags&^FoldCase) {
			return nil
		}
		re.Op = OpLiteral
		re.Rune = re.Rune[:1]
		re.Flags = p.flags &^ FoldCase
	} else if re.Op == OpCharClass && len(re.Rune) == 4 &&
		re.Rune[0] == re.Rune[1] && re.Rune[2] == re.Rune[3] &&

	case OpLiteral:
		for _, r := range re.Rune {
			escape(b, r, false)
		}
	case OpCharClass:
		if len(re.Rune)%2 != 0 {
			b.WriteString(`[invalid char class]`)
			break
		}
		b.WriteRune('[')
		if len(re.Rune) == 0 {
			b.WriteString(`^\x00-\x{10FFFF}`)
		} else if re.Rune[0] == 0 && re.Rune[len(re.Rune)-1] == unicode.MaxRune && len(re.Rune) > 2 {
			// Contains 0 and MaxRune. Probably a negated class.