docs:
- 'https://istio.io/latest/docs/setup/additional-setup/sidecar-injection/#customizing-injection'
releaseNotes:
- |

			if syntax.Flags(inst.Arg)&syntax.FoldCase != 0 {
				r0 := inst.Rune[0]
				runes = append(runes, r0, r0)
				for r1 := unicode.SimpleFold(r0); r1 != r0; r1 = unicode.SimpleFold(r1) {
					runes = append(runes, r1, r1)
				}
				slices.Sort(runes)
			} else {
				runes = append(runes, inst.Rune[0], inst.Rune[0])
			}
			onePassRunes[pc] = runes
			inst.Next = make([]uint32, len(onePassRunes[pc])/2+1)
			for i := range inst.Next {

				// is odd so we take the low bit from _case.
				return rune(cr.Lo) + ((r-rune(cr.Lo))&^1 | rune(_case&1)), true
			}
			return r + delta, true
		}
		if r < rune(cr.Lo) {
			hi = m
		} else {
			lo = m + 1
		}
	}
	return r, false
}

// To maps the rune to the specified case: [UpperCase], [LowerCase], or [TitleCase].
func To(_case int, r rune) rune {
	r, _ = to(_case, r, CaseRanges)
	return r
}

Jonh Wendell <******@****.***> 1715709579 -0400

//	2..0  case mode
//
// For the non-exceptional cases, a rune must be either uncased, lowercase or
// uppercase. If the rune is cased, the XOR pattern maps either a lowercase
// rune to uppercase or an uppercase rune to lowercase (applied to the 10
// least-significant bits of the rune).
//
// See the definitions below for a more detailed description of the various
// bits.
type info uint16

		[]rune{69, 74},
		[]rune{65, 69},
		[]rune{},
		[]uint32{mergeFailed},
		1, 2,
	},
	{
		// overlap from above
		[]rune{69, 74},
		[]rune{71, 74},
		[]rune{},
		[]uint32{mergeFailed},
		1, 2,
	},
	{
		// overlap from below
		[]rune{69, 74},
		[]rune{65, 71},
		[]rune{},
		[]uint32{mergeFailed},
		1, 2,
	},
	{
		// out of order []rune
		[]rune{69, 74, 60, 65},

		partLen = c.Rand.Intn(63) + 1 // len is [1, 63]
	}

	runes := make([]rune, partLen)
	if partLen == 0 {
		return string(runes)
	}

	runes[0] = validStartEnd[c.Rand.Intn(len(validStartEnd))].choose(c.Rand)
	for i := range runes[1:] {
		runes[i+1] = validMiddle[c.Rand.Intn(len(validMiddle))].choose(c.Rand)
	}
	runes[len(runes)-1] = validStartEnd[c.Rand.Intn(len(validStartEnd))].choose(c.Rand)

	bn := rb.rune[pos].pos
	sz := utf8.EncodeRune(rb.byte[bn:], rune(r))
	rb.rune[pos] = Properties{pos: bn, size: uint8(sz)}
}

// runeAt returns the rune at position n. It is used for Hangul and recomposition.
func (rb *reorderBuffer) runeAt(n int) rune {
	inf := rb.rune[n]
	r, _ := utf8.DecodeRune(rb.byte[inf.pos : inf.pos+inf.size])
	return r
}

	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] &&

var notletterTest = []rune{
	0x20,
	0x35,
	0x375,
	0x619,
	0x700,
	0x1885,
	0xfffe,
	0x1ffff,
	0x10ffff,
}

// Contains all the special cased Latin-1 chars.
var spaceTest = []rune{
	0x09,
	0x0a,
	0x0b,
	0x0c,
	0x0d,
	0x20,
	0x85,
	0xA0,
	0x2000,
	0x3000,
}

type caseT struct {
	cas     int
	in, out rune
}

var caseTest = []caseT{
	// errors