// But there are at least two subtle considerations.
//
// First, note that not all case-fold equivalent distinct runes
// form an upper/lower pair.
// For example, U+004B ('K'), U+006B ('k'), and U+212A ('K' for Kelvin)
// are three distinct runes that case-fold to each other.
// When we do add Unicode letters, we must not assume that upper/lower
// are the only case-equivalent pairs.

		Data:  Data{off + entryLen, size},
	})
}

// exactly16Bytes truncates the string if necessary so it is at most 16 bytes long,
// then pads the result with spaces to be exactly 16 bytes.
// Fmt uses runes for its width calculation, but we need bytes in the entry header.
func exactly16Bytes(s string) string {
	for len(s) > 16 {
		_, wid := utf8.DecodeLastRuneInString(s)
		s = s[:len(s)-wid]
	}

// 3) asciiEqualFold, no special, but includes non-letters (including _)
// 4) simpleLetterEqualFold, no specials, no non-letters.
//
// The letters S and K are special because they map to 3 runes, not just 2:
//  * S maps to s and to U+017F 'ſ' Latin small letter long s
//  * k maps to K and to U+212A 'K' Kelvin sign
// See http://play.golang.org/p/tTxjOc0OGo
//

	return s
}

// replace replaces each rune r of s with replacementTable[r], provided that
// r < len(replacementTable). If replacementTable[r] is the empty string then
// no replacement is made.
// It also replaces runes U+2028 and U+2029 with the raw strings `\u2028` and
// `\u2029`.
func replace(s string, replacementTable []string) string {
	var b strings.Builder
	r, w, written := rune(0), 0, 0
	for i := 0; i < len(s); i += w {

<li>
Converting a value of a string type to a slice of runes type
yields a slice containing the individual Unicode code points of the string.

<pre>
[]rune(myString("白鵬翔"))   // []rune{0x767d, 0x9d6c, 0x7fd4}
[]rune("")                  // []rune{}

runes("白鵬翔")              // []rune{0x767d, 0x9d6c, 0x7fd4}

[]myRune("♫♬")              // []myRune{0x266b, 0x266c}
[]myRune(myString("🌐"))    // []myRune{0x1f310}
</pre>

// the start of the field with the given index in the slice most recently
// returned by [Reader.Read]. Numbering of lines and columns starts at 1;
// columns are counted in bytes, not runes.
//
// If this is called with an out-of-bounds index, it panics.
func (r *Reader) FieldPos(field int) (line, column int) {
	if field < 0 || field >= len(r.fieldPositions) {
		panic("out of range index passed to FieldPos")

	}
	t.inst = i
	return t
}

// A lazyFlag is a lazily-evaluated syntax.EmptyOp,
// for checking zero-width flags like ^ $ \A \z \B \b.
// It records the pair of relevant runes and does not
// determine the implied flags until absolutely necessary
// (most of the time, that means never).
type lazyFlag uint64

func newLazyFlag(r1, r2 rune) lazyFlag {

}

func (s *phiState) insertPhis() {
	if debugPhi {
		fmt.Println(s.f.String())
	}

	// Find all the variables for which we need to match up reads & writes.
	// This step prunes any basic-block-only variables from consideration.
	// Generate a numbering for these variables.
	s.varnum = map[ir.Node]int32{}
	var vars []ir.Node
	var vartypes []*types.Type
	for _, b := range s.f.Blocks {

	"(" + strings.Repeat("(xx?)", 1000) + "){1000}",          // too long
	strings.Repeat("(xx?){1000}", 1000),                      // too long
	strings.Repeat(`\pL`, 27000),                             // too many runes
}

var onlyPerl = []string{
	`[a-b-c]`,
	`\Qabc\E`,
	`\Q*+?{[\E`,
	`\Q\\E`,
	`\Q\\\E`,
	`\Q\\\\E`,
	`\Q\\\\\E`,
	`(?:a)`,
	`(?P<name>a)`,
}

var onlyPOSIX = []string{

func (l *lexer) accept(valid string) bool {
	if strings.ContainsRune(valid, l.next()) {
		return true
	}
	l.backup()
	return false
}

// acceptRun consumes a run of runes from the valid set.
func (l *lexer) acceptRun(valid string) {
	for strings.ContainsRune(valid, l.next()) {
	}
	l.backup()
}

// errorf returns an error token and terminates the scan by passing