Add labels to tasks (#45)

vendor/honnef.co/go/tools/staticcheck/CONTRIBUTING.md

@@ -0,0 +1,15 @@
+# Contributing to staticcheck
+
+## Before filing an issue:
+
+### Are you having trouble building staticcheck?
+
+Check you have the latest version of its dependencies. Run
+```
+go get -u honnef.co/go/tools/staticcheck
+```
+If you still have problems, consider searching for existing issues before filing a new issue.
+
+## Before sending a pull request:
+
+Have you understood the purpose of staticcheck? Make sure to carefully read `README`.

vendor/honnef.co/go/tools/staticcheck/buildtag.go

@@ -0,0 +1,21 @@
+package staticcheck
+
+import (
+	"go/ast"
+	"strings"
+
+	. "honnef.co/go/tools/lint/lintdsl"
+)
+
+func buildTags(f *ast.File) [][]string {
+	var out [][]string
+	for _, line := range strings.Split(Preamble(f), "\n") {
+		if !strings.HasPrefix(line, "+build ") {
+			continue
+		}
+		line = strings.TrimSpace(strings.TrimPrefix(line, "+build "))
+		fields := strings.Fields(line)
+		out = append(out, fields)
+	}
+	return out
+}

vendor/honnef.co/go/tools/staticcheck/rules.go

@@ -0,0 +1,322 @@
+package staticcheck
+
+import (
+	"fmt"
+	"go/constant"
+	"go/types"
+	"net"
+	"net/url"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+	"unicode/utf8"
+
+	"honnef.co/go/tools/lint"
+	. "honnef.co/go/tools/lint/lintdsl"
+	"honnef.co/go/tools/ssa"
+	"honnef.co/go/tools/staticcheck/vrp"
+)
+
+const (
+	MsgInvalidHostPort = "invalid port or service name in host:port pair"
+	MsgInvalidUTF8     = "argument is not a valid UTF-8 encoded string"
+	MsgNonUniqueCutset = "cutset contains duplicate characters"
+)
+
+type Call struct {
+	Job   *lint.Job
+	Instr ssa.CallInstruction
+	Args  []*Argument
+
+	Checker *Checker
+	Parent  *ssa.Function
+
+	invalids []string
+}
+
+func (c *Call) Invalid(msg string) {
+	c.invalids = append(c.invalids, msg)
+}
+
+type Argument struct {
+	Value    Value
+	invalids []string
+}
+
+func (arg *Argument) Invalid(msg string) {
+	arg.invalids = append(arg.invalids, msg)
+}
+
+type Value struct {
+	Value ssa.Value
+	Range vrp.Range
+}
+
+type CallCheck func(call *Call)
+
+func extractConsts(v ssa.Value) []*ssa.Const {
+	switch v := v.(type) {
+	case *ssa.Const:
+		return []*ssa.Const{v}
+	case *ssa.MakeInterface:
+		return extractConsts(v.X)
+	default:
+		return nil
+	}
+}
+
+func ValidateRegexp(v Value) error {
+	for _, c := range extractConsts(v.Value) {
+		if c.Value == nil {
+			continue
+		}
+		if c.Value.Kind() != constant.String {
+			continue
+		}
+		s := constant.StringVal(c.Value)
+		if _, err := regexp.Compile(s); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func ValidateTimeLayout(v Value) error {
+	for _, c := range extractConsts(v.Value) {
+		if c.Value == nil {
+			continue
+		}
+		if c.Value.Kind() != constant.String {
+			continue
+		}
+		s := constant.StringVal(c.Value)
+		s = strings.Replace(s, "_", " ", -1)
+		s = strings.Replace(s, "Z", "-", -1)
+		_, err := time.Parse(s, s)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func ValidateURL(v Value) error {
+	for _, c := range extractConsts(v.Value) {
+		if c.Value == nil {
+			continue
+		}
+		if c.Value.Kind() != constant.String {
+			continue
+		}
+		s := constant.StringVal(c.Value)
+		_, err := url.Parse(s)
+		if err != nil {
+			return fmt.Errorf("%q is not a valid URL: %s", s, err)
+		}
+	}
+	return nil
+}
+
+func IntValue(v Value, z vrp.Z) bool {
+	r, ok := v.Range.(vrp.IntInterval)
+	if !ok || !r.IsKnown() {
+		return false
+	}
+	if r.Lower != r.Upper {
+		return false
+	}
+	if r.Lower.Cmp(z) == 0 {
+		return true
+	}
+	return false
+}
+
+func InvalidUTF8(v Value) bool {
+	for _, c := range extractConsts(v.Value) {
+		if c.Value == nil {
+			continue
+		}
+		if c.Value.Kind() != constant.String {
+			continue
+		}
+		s := constant.StringVal(c.Value)
+		if !utf8.ValidString(s) {
+			return true
+		}
+	}
+	return false
+}
+
+func UnbufferedChannel(v Value) bool {
+	r, ok := v.Range.(vrp.ChannelInterval)
+	if !ok || !r.IsKnown() {
+		return false
+	}
+	if r.Size.Lower.Cmp(vrp.NewZ(0)) == 0 &&
+		r.Size.Upper.Cmp(vrp.NewZ(0)) == 0 {
+		return true
+	}
+	return false
+}
+
+func Pointer(v Value) bool {
+	switch v.Value.Type().Underlying().(type) {
+	case *types.Pointer, *types.Interface:
+		return true
+	}
+	return false
+}
+
+func ConvertedFromInt(v Value) bool {
+	conv, ok := v.Value.(*ssa.Convert)
+	if !ok {
+		return false
+	}
+	b, ok := conv.X.Type().Underlying().(*types.Basic)
+	if !ok {
+		return false
+	}
+	if (b.Info() & types.IsInteger) == 0 {
+		return false
+	}
+	return true
+}
+
+func validEncodingBinaryType(j *lint.Job, typ types.Type) bool {
+	typ = typ.Underlying()
+	switch typ := typ.(type) {
+	case *types.Basic:
+		switch typ.Kind() {
+		case types.Uint8, types.Uint16, types.Uint32, types.Uint64,
+			types.Int8, types.Int16, types.Int32, types.Int64,
+			types.Float32, types.Float64, types.Complex64, types.Complex128, types.Invalid:
+			return true
+		case types.Bool:
+			return IsGoVersion(j, 8)
+		}
+		return false
+	case *types.Struct:
+		n := typ.NumFields()
+		for i := 0; i < n; i++ {
+			if !validEncodingBinaryType(j, typ.Field(i).Type()) {
+				return false
+			}
+		}
+		return true
+	case *types.Array:
+		return validEncodingBinaryType(j, typ.Elem())
+	case *types.Interface:
+		// we can't determine if it's a valid type or not
+		return true
+	}
+	return false
+}
+
+func CanBinaryMarshal(j *lint.Job, v Value) bool {
+	typ := v.Value.Type().Underlying()
+	if ttyp, ok := typ.(*types.Pointer); ok {
+		typ = ttyp.Elem().Underlying()
+	}
+	if ttyp, ok := typ.(interface {
+		Elem() types.Type
+	}); ok {
+		if _, ok := ttyp.(*types.Pointer); !ok {
+			typ = ttyp.Elem()
+		}
+	}
+
+	return validEncodingBinaryType(j, typ)
+}
+
+func RepeatZeroTimes(name string, arg int) CallCheck {
+	return func(call *Call) {
+		arg := call.Args[arg]
+		if IntValue(arg.Value, vrp.NewZ(0)) {
+			arg.Invalid(fmt.Sprintf("calling %s with n == 0 will return no results, did you mean -1?", name))
+		}
+	}
+}
+
+func validateServiceName(s string) bool {
+	if len(s) < 1 || len(s) > 15 {
+		return false
+	}
+	if s[0] == '-' || s[len(s)-1] == '-' {
+		return false
+	}
+	if strings.Contains(s, "--") {
+		return false
+	}
+	hasLetter := false
+	for _, r := range s {
+		if (r >= 'A' && r <= 'Z') || (r >= 'a' && r <= 'z') {
+			hasLetter = true
+			continue
+		}
+		if r >= '0' && r <= '9' {
+			continue
+		}
+		return false
+	}
+	return hasLetter
+}
+
+func validatePort(s string) bool {
+	n, err := strconv.ParseInt(s, 10, 64)
+	if err != nil {
+		return validateServiceName(s)
+	}
+	return n >= 0 && n <= 65535
+}
+
+func ValidHostPort(v Value) bool {
+	for _, k := range extractConsts(v.Value) {
+		if k.Value == nil {
+			continue
+		}
+		if k.Value.Kind() != constant.String {
+			continue
+		}
+		s := constant.StringVal(k.Value)
+		_, port, err := net.SplitHostPort(s)
+		if err != nil {
+			return false
+		}
+		// TODO(dh): check hostname
+		if !validatePort(port) {
+			return false
+		}
+	}
+	return true
+}
+
+// ConvertedFrom reports whether value v was converted from type typ.
+func ConvertedFrom(v Value, typ string) bool {
+	change, ok := v.Value.(*ssa.ChangeType)
+	return ok && IsType(change.X.Type(), typ)
+}
+
+func UniqueStringCutset(v Value) bool {
+	for _, c := range extractConsts(v.Value) {
+		if c.Value == nil {
+			continue
+		}
+		if c.Value.Kind() != constant.String {
+			continue
+		}
+		s := constant.StringVal(c.Value)
+		rs := runeSlice(s)
+		if len(rs) < 2 {
+			continue
+		}
+		sort.Sort(rs)
+		for i, r := range rs[1:] {
+			if rs[i] == r {
+				return false
+			}
+		}
+	}
+	return true
+}

vendor/honnef.co/go/tools/staticcheck/vrp/channel.go

@@ -0,0 +1,73 @@
+package vrp
+
+import (
+	"fmt"
+
+	"honnef.co/go/tools/ssa"
+)
+
+type ChannelInterval struct {
+	Size IntInterval
+}
+
+func (c ChannelInterval) Union(other Range) Range {
+	i, ok := other.(ChannelInterval)
+	if !ok {
+		i = ChannelInterval{EmptyIntInterval}
+	}
+	if c.Size.Empty() || !c.Size.IsKnown() {
+		return i
+	}
+	if i.Size.Empty() || !i.Size.IsKnown() {
+		return c
+	}
+	return ChannelInterval{
+		Size: c.Size.Union(i.Size).(IntInterval),
+	}
+}
+
+func (c ChannelInterval) String() string {
+	return c.Size.String()
+}
+
+func (c ChannelInterval) IsKnown() bool {
+	return c.Size.IsKnown()
+}
+
+type MakeChannelConstraint struct {
+	aConstraint
+	Buffer ssa.Value
+}
+type ChannelChangeTypeConstraint struct {
+	aConstraint
+	X ssa.Value
+}
+
+func NewMakeChannelConstraint(buffer, y ssa.Value) Constraint {
+	return &MakeChannelConstraint{NewConstraint(y), buffer}
+}
+func NewChannelChangeTypeConstraint(x, y ssa.Value) Constraint {
+	return &ChannelChangeTypeConstraint{NewConstraint(y), x}
+}
+
+func (c *MakeChannelConstraint) Operands() []ssa.Value       { return []ssa.Value{c.Buffer} }
+func (c *ChannelChangeTypeConstraint) Operands() []ssa.Value { return []ssa.Value{c.X} }
+
+func (c *MakeChannelConstraint) String() string {
+	return fmt.Sprintf("%s = make(chan, %s)", c.Y().Name(), c.Buffer.Name())
+}
+func (c *ChannelChangeTypeConstraint) String() string {
+	return fmt.Sprintf("%s = changetype(%s)", c.Y().Name(), c.X.Name())
+}
+
+func (c *MakeChannelConstraint) Eval(g *Graph) Range {
+	i, ok := g.Range(c.Buffer).(IntInterval)
+	if !ok {
+		return ChannelInterval{NewIntInterval(NewZ(0), PInfinity)}
+	}
+	if i.Lower.Sign() == -1 {
+		i.Lower = NewZ(0)
+	}
+	return ChannelInterval{i}
+}
+func (c *ChannelChangeTypeConstraint) Eval(g *Graph) Range { return g.Range(c.X) }

vendor/honnef.co/go/tools/staticcheck/vrp/int.go

@@ -0,0 +1,476 @@
+package vrp
+
+import (
+	"fmt"
+	"go/token"
+	"go/types"
+	"math/big"
+
+	"honnef.co/go/tools/ssa"
+)
+
+type Zs []Z
+
+func (zs Zs) Len() int {
+	return len(zs)
+}
+
+func (zs Zs) Less(i int, j int) bool {
+	return zs[i].Cmp(zs[j]) == -1
+}
+
+func (zs Zs) Swap(i int, j int) {
+	zs[i], zs[j] = zs[j], zs[i]
+}
+
+type Z struct {
+	infinity int8
+	integer  *big.Int
+}
+
+func NewZ(n int64) Z {
+	return NewBigZ(big.NewInt(n))
+}
+
+func NewBigZ(n *big.Int) Z {
+	return Z{integer: n}
+}
+
+func (z1 Z) Infinite() bool {
+	return z1.infinity != 0
+}
+
+func (z1 Z) Add(z2 Z) Z {
+	if z2.Sign() == -1 {
+		return z1.Sub(z2.Negate())
+	}
+	if z1 == NInfinity {
+		return NInfinity
+	}
+	if z1 == PInfinity {
+		return PInfinity
+	}
+	if z2 == PInfinity {
+		return PInfinity
+	}
+
+	if !z1.Infinite() && !z2.Infinite() {
+		n := &big.Int{}
+		n.Add(z1.integer, z2.integer)
+		return NewBigZ(n)
+	}
+
+	panic(fmt.Sprintf("%s + %s is not defined", z1, z2))
+}
+
+func (z1 Z) Sub(z2 Z) Z {
+	if z2.Sign() == -1 {
+		return z1.Add(z2.Negate())
+	}
+	if !z1.Infinite() && !z2.Infinite() {
+		n := &big.Int{}
+		n.Sub(z1.integer, z2.integer)
+		return NewBigZ(n)
+	}
+
+	if z1 != PInfinity && z2 == PInfinity {
+		return NInfinity
+	}
+	if z1.Infinite() && !z2.Infinite() {
+		return Z{infinity: z1.infinity}
+	}
+	if z1 == PInfinity && z2 == PInfinity {
+		return PInfinity
+	}
+	panic(fmt.Sprintf("%s - %s is not defined", z1, z2))
+}
+
+func (z1 Z) Mul(z2 Z) Z {
+	if (z1.integer != nil && z1.integer.Sign() == 0) ||
+		(z2.integer != nil && z2.integer.Sign() == 0) {
+		return NewBigZ(&big.Int{})
+	}
+
+	if z1.infinity != 0 || z2.infinity != 0 {
+		return Z{infinity: int8(z1.Sign() * z2.Sign())}
+	}
+
+	n := &big.Int{}
+	n.Mul(z1.integer, z2.integer)
+	return NewBigZ(n)
+}
+
+func (z1 Z) Negate() Z {
+	if z1.infinity == 1 {
+		return NInfinity
+	}
+	if z1.infinity == -1 {
+		return PInfinity
+	}
+	n := &big.Int{}
+	n.Neg(z1.integer)
+	return NewBigZ(n)
+}
+
+func (z1 Z) Sign() int {
+	if z1.infinity != 0 {
+		return int(z1.infinity)
+	}
+	return z1.integer.Sign()
+}
+
+func (z1 Z) String() string {
+	if z1 == NInfinity {
+		return "-∞"
+	}
+	if z1 == PInfinity {
+		return "∞"
+	}
+	return fmt.Sprintf("%d", z1.integer)
+}
+
+func (z1 Z) Cmp(z2 Z) int {
+	if z1.infinity == z2.infinity && z1.infinity != 0 {
+		return 0
+	}
+	if z1 == PInfinity {
+		return 1
+	}
+	if z1 == NInfinity {
+		return -1
+	}
+	if z2 == NInfinity {
+		return 1
+	}
+	if z2 == PInfinity {
+		return -1
+	}
+	return z1.integer.Cmp(z2.integer)
+}
+
+func MaxZ(zs ...Z) Z {
+	if len(zs) == 0 {
+		panic("Max called with no arguments")
+	}
+	if len(zs) == 1 {
+		return zs[0]
+	}
+	ret := zs[0]
+	for _, z := range zs[1:] {
+		if z.Cmp(ret) == 1 {
+			ret = z
+		}
+	}
+	return ret
+}
+
+func MinZ(zs ...Z) Z {
+	if len(zs) == 0 {
+		panic("Min called with no arguments")
+	}
+	if len(zs) == 1 {
+		return zs[0]
+	}
+	ret := zs[0]
+	for _, z := range zs[1:] {
+		if z.Cmp(ret) == -1 {
+			ret = z
+		}
+	}
+	return ret
+}
+
+var NInfinity = Z{infinity: -1}
+var PInfinity = Z{infinity: 1}
+var EmptyIntInterval = IntInterval{true, PInfinity, NInfinity}
+
+func InfinityFor(v ssa.Value) IntInterval {
+	if b, ok := v.Type().Underlying().(*types.Basic); ok {
+		if (b.Info() & types.IsUnsigned) != 0 {
+			return NewIntInterval(NewZ(0), PInfinity)
+		}
+	}
+	return NewIntInterval(NInfinity, PInfinity)
+}
+
+type IntInterval struct {
+	known bool
+	Lower Z
+	Upper Z
+}
+
+func NewIntInterval(l, u Z) IntInterval {
+	if u.Cmp(l) == -1 {
+		return EmptyIntInterval
+	}
+	return IntInterval{known: true, Lower: l, Upper: u}
+}
+
+func (i IntInterval) IsKnown() bool {
+	return i.known
+}
+
+func (i IntInterval) Empty() bool {
+	return i.Lower == PInfinity && i.Upper == NInfinity
+}
+
+func (i IntInterval) IsMaxRange() bool {
+	return i.Lower == NInfinity && i.Upper == PInfinity
+}
+
+func (i1 IntInterval) Intersection(i2 IntInterval) IntInterval {
+	if !i1.IsKnown() {
+		return i2
+	}
+	if !i2.IsKnown() {
+		return i1
+	}
+	if i1.Empty() || i2.Empty() {
+		return EmptyIntInterval
+	}
+	i3 := NewIntInterval(MaxZ(i1.Lower, i2.Lower), MinZ(i1.Upper, i2.Upper))
+	if i3.Lower.Cmp(i3.Upper) == 1 {
+		return EmptyIntInterval
+	}
+	return i3
+}
+
+func (i1 IntInterval) Union(other Range) Range {
+	i2, ok := other.(IntInterval)
+	if !ok {
+		i2 = EmptyIntInterval
+	}
+	if i1.Empty() || !i1.IsKnown() {
+		return i2
+	}
+	if i2.Empty() || !i2.IsKnown() {
+		return i1
+	}
+	return NewIntInterval(MinZ(i1.Lower, i2.Lower), MaxZ(i1.Upper, i2.Upper))
+}
+
+func (i1 IntInterval) Add(i2 IntInterval) IntInterval {
+	if i1.Empty() || i2.Empty() {
+		return EmptyIntInterval
+	}
+	l1, u1, l2, u2 := i1.Lower, i1.Upper, i2.Lower, i2.Upper
+	return NewIntInterval(l1.Add(l2), u1.Add(u2))
+}
+
+func (i1 IntInterval) Sub(i2 IntInterval) IntInterval {
+	if i1.Empty() || i2.Empty() {
+		return EmptyIntInterval
+	}
+	l1, u1, l2, u2 := i1.Lower, i1.Upper, i2.Lower, i2.Upper
+	return NewIntInterval(l1.Sub(u2), u1.Sub(l2))
+}
+
+func (i1 IntInterval) Mul(i2 IntInterval) IntInterval {
+	if i1.Empty() || i2.Empty() {
+		return EmptyIntInterval
+	}
+	x1, x2 := i1.Lower, i1.Upper
+	y1, y2 := i2.Lower, i2.Upper
+	return NewIntInterval(
+		MinZ(x1.Mul(y1), x1.Mul(y2), x2.Mul(y1), x2.Mul(y2)),
+		MaxZ(x1.Mul(y1), x1.Mul(y2), x2.Mul(y1), x2.Mul(y2)),
+	)
+}
+
+func (i1 IntInterval) String() string {
+	if !i1.IsKnown() {
+		return "[⊥, ⊥]"
+	}
+	if i1.Empty() {
+		return "{}"
+	}
+	return fmt.Sprintf("[%s, %s]", i1.Lower, i1.Upper)
+}
+
+type IntArithmeticConstraint struct {
+	aConstraint
+	A  ssa.Value
+	B  ssa.Value
+	Op token.Token
+	Fn func(IntInterval, IntInterval) IntInterval
+}
+
+type IntAddConstraint struct{ *IntArithmeticConstraint }
+type IntSubConstraint struct{ *IntArithmeticConstraint }
+type IntMulConstraint struct{ *IntArithmeticConstraint }
+
+type IntConversionConstraint struct {
+	aConstraint
+	X ssa.Value
+}
+
+type IntIntersectionConstraint struct {
+	aConstraint
+	ranges   Ranges
+	A        ssa.Value
+	B        ssa.Value
+	Op       token.Token
+	I        IntInterval
+	resolved bool
+}
+
+type IntIntervalConstraint struct {
+	aConstraint
+	I IntInterval
+}
+
+func NewIntArithmeticConstraint(a, b, y ssa.Value, op token.Token, fn func(IntInterval, IntInterval) IntInterval) *IntArithmeticConstraint {
+	return &IntArithmeticConstraint{NewConstraint(y), a, b, op, fn}
+}
+func NewIntAddConstraint(a, b, y ssa.Value) Constraint {
+	return &IntAddConstraint{NewIntArithmeticConstraint(a, b, y, token.ADD, IntInterval.Add)}
+}
+func NewIntSubConstraint(a, b, y ssa.Value) Constraint {
+	return &IntSubConstraint{NewIntArithmeticConstraint(a, b, y, token.SUB, IntInterval.Sub)}
+}
+func NewIntMulConstraint(a, b, y ssa.Value) Constraint {
+	return &IntMulConstraint{NewIntArithmeticConstraint(a, b, y, token.MUL, IntInterval.Mul)}
+}
+func NewIntConversionConstraint(x, y ssa.Value) Constraint {
+	return &IntConversionConstraint{NewConstraint(y), x}
+}
+func NewIntIntersectionConstraint(a, b ssa.Value, op token.Token, ranges Ranges, y ssa.Value) Constraint {
+	return &IntIntersectionConstraint{
+		aConstraint: NewConstraint(y),
+		ranges:      ranges,
+		A:           a,
+		B:           b,
+		Op:          op,
+	}
+}
+func NewIntIntervalConstraint(i IntInterval, y ssa.Value) Constraint {
+	return &IntIntervalConstraint{NewConstraint(y), i}
+}
+
+func (c *IntArithmeticConstraint) Operands() []ssa.Value   { return []ssa.Value{c.A, c.B} }
+func (c *IntConversionConstraint) Operands() []ssa.Value   { return []ssa.Value{c.X} }
+func (c *IntIntersectionConstraint) Operands() []ssa.Value { return []ssa.Value{c.A} }
+func (s *IntIntervalConstraint) Operands() []ssa.Value     { return nil }
+
+func (c *IntArithmeticConstraint) String() string {
+	return fmt.Sprintf("%s = %s %s %s", c.Y().Name(), c.A.Name(), c.Op, c.B.Name())
+}
+func (c *IntConversionConstraint) String() string {
+	return fmt.Sprintf("%s = %s(%s)", c.Y().Name(), c.Y().Type(), c.X.Name())
+}
+func (c *IntIntersectionConstraint) String() string {
+	return fmt.Sprintf("%s = %s %s %s (%t branch)", c.Y().Name(), c.A.Name(), c.Op, c.B.Name(), c.Y().(*ssa.Sigma).Branch)
+}
+func (c *IntIntervalConstraint) String() string { return fmt.Sprintf("%s = %s", c.Y().Name(), c.I) }
+
+func (c *IntArithmeticConstraint) Eval(g *Graph) Range {
+	i1, i2 := g.Range(c.A).(IntInterval), g.Range(c.B).(IntInterval)
+	if !i1.IsKnown() || !i2.IsKnown() {
+		return IntInterval{}
+	}
+	return c.Fn(i1, i2)
+}
+func (c *IntConversionConstraint) Eval(g *Graph) Range {
+	s := &types.StdSizes{
+		// XXX is it okay to assume the largest word size, or do we
+		// need to be platform specific?
+		WordSize: 8,
+		MaxAlign: 1,
+	}
+	fromI := g.Range(c.X).(IntInterval)
+	toI := g.Range(c.Y()).(IntInterval)
+	fromT := c.X.Type().Underlying().(*types.Basic)
+	toT := c.Y().Type().Underlying().(*types.Basic)
+	fromB := s.Sizeof(c.X.Type())
+	toB := s.Sizeof(c.Y().Type())
+
+	if !fromI.IsKnown() {
+		return toI
+	}
+	if !toI.IsKnown() {
+		return fromI
+	}
+
+	// uint<N> -> sint/uint<M>, M > N: [max(0, l1), min(2**N-1, u2)]
+	if (fromT.Info()&types.IsUnsigned != 0) &&
+		toB > fromB {
+
+		n := big.NewInt(1)
+		n.Lsh(n, uint(fromB*8))
+		n.Sub(n, big.NewInt(1))
+		return NewIntInterval(
+			MaxZ(NewZ(0), fromI.Lower),
+			MinZ(NewBigZ(n), toI.Upper),
+		)
+	}
+
+	// sint<N> -> sint<M>, M > N; [max(-∞, l1), min(2**N-1, u2)]
+	if (fromT.Info()&types.IsUnsigned == 0) &&
+		(toT.Info()&types.IsUnsigned == 0) &&
+		toB > fromB {
+
+		n := big.NewInt(1)
+		n.Lsh(n, uint(fromB*8))
+		n.Sub(n, big.NewInt(1))
+		return NewIntInterval(
+			MaxZ(NInfinity, fromI.Lower),
+			MinZ(NewBigZ(n), toI.Upper),
+		)
+	}
+
+	return fromI
+}
+func (c *IntIntersectionConstraint) Eval(g *Graph) Range {
+	xi := g.Range(c.A).(IntInterval)
+	if !xi.IsKnown() {
+		return c.I
+	}
+	return xi.Intersection(c.I)
+}
+func (c *IntIntervalConstraint) Eval(*Graph) Range { return c.I }
+
+func (c *IntIntersectionConstraint) Futures() []ssa.Value {
+	return []ssa.Value{c.B}
+}
+
+func (c *IntIntersectionConstraint) Resolve() {
+	r, ok := c.ranges[c.B].(IntInterval)
+	if !ok {
+		c.I = InfinityFor(c.Y())
+		return
+	}
+
+	switch c.Op {
+	case token.EQL:
+		c.I = r
+	case token.GTR:
+		c.I = NewIntInterval(r.Lower.Add(NewZ(1)), PInfinity)
+	case token.GEQ:
+		c.I = NewIntInterval(r.Lower, PInfinity)
+	case token.LSS:
+		// TODO(dh): do we need 0 instead of NInfinity for uints?
+		c.I = NewIntInterval(NInfinity, r.Upper.Sub(NewZ(1)))
+	case token.LEQ:
+		c.I = NewIntInterval(NInfinity, r.Upper)
+	case token.NEQ:
+		c.I = InfinityFor(c.Y())
+	default:
+		panic("unsupported op " + c.Op.String())
+	}
+}
+
+func (c *IntIntersectionConstraint) IsKnown() bool {
+	return c.I.IsKnown()
+}
+
+func (c *IntIntersectionConstraint) MarkUnresolved() {
+	c.resolved = false
+}
+
+func (c *IntIntersectionConstraint) MarkResolved() {
+	c.resolved = true
+}
+
+func (c *IntIntersectionConstraint) IsResolved() bool {
+	return c.resolved
+}

vendor/honnef.co/go/tools/staticcheck/vrp/slice.go

@@ -0,0 +1,273 @@
+package vrp
+
+// TODO(dh): most of the constraints have implementations identical to
+// that of strings. Consider reusing them.
+
+import (
+	"fmt"
+	"go/types"
+
+	"honnef.co/go/tools/ssa"
+)
+
+type SliceInterval struct {
+	Length IntInterval
+}
+
+func (s SliceInterval) Union(other Range) Range {
+	i, ok := other.(SliceInterval)
+	if !ok {
+		i = SliceInterval{EmptyIntInterval}
+	}
+	if s.Length.Empty() || !s.Length.IsKnown() {
+		return i
+	}
+	if i.Length.Empty() || !i.Length.IsKnown() {
+		return s
+	}
+	return SliceInterval{
+		Length: s.Length.Union(i.Length).(IntInterval),
+	}
+}
+func (s SliceInterval) String() string { return s.Length.String() }
+func (s SliceInterval) IsKnown() bool  { return s.Length.IsKnown() }
+
+type SliceAppendConstraint struct {
+	aConstraint
+	A ssa.Value
+	B ssa.Value
+}
+
+type SliceSliceConstraint struct {
+	aConstraint
+	X     ssa.Value
+	Lower ssa.Value
+	Upper ssa.Value
+}
+
+type ArraySliceConstraint struct {
+	aConstraint
+	X     ssa.Value
+	Lower ssa.Value
+	Upper ssa.Value
+}
+
+type SliceIntersectionConstraint struct {
+	aConstraint
+	X ssa.Value
+	I IntInterval
+}
+
+type SliceLengthConstraint struct {
+	aConstraint
+	X ssa.Value
+}
+
+type MakeSliceConstraint struct {
+	aConstraint
+	Size ssa.Value
+}
+
+type SliceIntervalConstraint struct {
+	aConstraint
+	I IntInterval
+}
+
+func NewSliceAppendConstraint(a, b, y ssa.Value) Constraint {
+	return &SliceAppendConstraint{NewConstraint(y), a, b}
+}
+func NewSliceSliceConstraint(x, lower, upper, y ssa.Value) Constraint {
+	return &SliceSliceConstraint{NewConstraint(y), x, lower, upper}
+}
+func NewArraySliceConstraint(x, lower, upper, y ssa.Value) Constraint {
+	return &ArraySliceConstraint{NewConstraint(y), x, lower, upper}
+}
+func NewSliceIntersectionConstraint(x ssa.Value, i IntInterval, y ssa.Value) Constraint {
+	return &SliceIntersectionConstraint{NewConstraint(y), x, i}
+}
+func NewSliceLengthConstraint(x, y ssa.Value) Constraint {
+	return &SliceLengthConstraint{NewConstraint(y), x}
+}
+func NewMakeSliceConstraint(size, y ssa.Value) Constraint {
+	return &MakeSliceConstraint{NewConstraint(y), size}
+}
+func NewSliceIntervalConstraint(i IntInterval, y ssa.Value) Constraint {
+	return &SliceIntervalConstraint{NewConstraint(y), i}
+}
+
+func (c *SliceAppendConstraint) Operands() []ssa.Value { return []ssa.Value{c.A, c.B} }
+func (c *SliceSliceConstraint) Operands() []ssa.Value {
+	ops := []ssa.Value{c.X}
+	if c.Lower != nil {
+		ops = append(ops, c.Lower)
+	}
+	if c.Upper != nil {
+		ops = append(ops, c.Upper)
+	}
+	return ops
+}
+func (c *ArraySliceConstraint) Operands() []ssa.Value {
+	ops := []ssa.Value{c.X}
+	if c.Lower != nil {
+		ops = append(ops, c.Lower)
+	}
+	if c.Upper != nil {
+		ops = append(ops, c.Upper)
+	}
+	return ops
+}
+func (c *SliceIntersectionConstraint) Operands() []ssa.Value { return []ssa.Value{c.X} }
+func (c *SliceLengthConstraint) Operands() []ssa.Value       { return []ssa.Value{c.X} }
+func (c *MakeSliceConstraint) Operands() []ssa.Value         { return []ssa.Value{c.Size} }
+func (s *SliceIntervalConstraint) Operands() []ssa.Value     { return nil }
+
+func (c *SliceAppendConstraint) String() string {
+	return fmt.Sprintf("%s = append(%s, %s)", c.Y().Name(), c.A.Name(), c.B.Name())
+}
+func (c *SliceSliceConstraint) String() string {
+	var lname, uname string
+	if c.Lower != nil {
+		lname = c.Lower.Name()
+	}
+	if c.Upper != nil {
+		uname = c.Upper.Name()
+	}
+	return fmt.Sprintf("%s[%s:%s]", c.X.Name(), lname, uname)
+}
+func (c *ArraySliceConstraint) String() string {
+	var lname, uname string
+	if c.Lower != nil {
+		lname = c.Lower.Name()
+	}
+	if c.Upper != nil {
+		uname = c.Upper.Name()
+	}
+	return fmt.Sprintf("%s[%s:%s]", c.X.Name(), lname, uname)
+}
+func (c *SliceIntersectionConstraint) String() string {
+	return fmt.Sprintf("%s = %s.%t ⊓ %s", c.Y().Name(), c.X.Name(), c.Y().(*ssa.Sigma).Branch, c.I)
+}
+func (c *SliceLengthConstraint) String() string {
+	return fmt.Sprintf("%s = len(%s)", c.Y().Name(), c.X.Name())
+}
+func (c *MakeSliceConstraint) String() string {
+	return fmt.Sprintf("%s = make(slice, %s)", c.Y().Name(), c.Size.Name())
+}
+func (c *SliceIntervalConstraint) String() string { return fmt.Sprintf("%s = %s", c.Y().Name(), c.I) }
+
+func (c *SliceAppendConstraint) Eval(g *Graph) Range {
+	l1 := g.Range(c.A).(SliceInterval).Length
+	var l2 IntInterval
+	switch r := g.Range(c.B).(type) {
+	case SliceInterval:
+		l2 = r.Length
+	case StringInterval:
+		l2 = r.Length
+	default:
+		return SliceInterval{}
+	}
+	if !l1.IsKnown() || !l2.IsKnown() {
+		return SliceInterval{}
+	}
+	return SliceInterval{
+		Length: l1.Add(l2),
+	}
+}
+func (c *SliceSliceConstraint) Eval(g *Graph) Range {
+	lr := NewIntInterval(NewZ(0), NewZ(0))
+	if c.Lower != nil {
+		lr = g.Range(c.Lower).(IntInterval)
+	}
+	ur := g.Range(c.X).(SliceInterval).Length
+	if c.Upper != nil {
+		ur = g.Range(c.Upper).(IntInterval)
+	}
+	if !lr.IsKnown() || !ur.IsKnown() {
+		return SliceInterval{}
+	}
+
+	ls := []Z{
+		ur.Lower.Sub(lr.Lower),
+		ur.Upper.Sub(lr.Lower),
+		ur.Lower.Sub(lr.Upper),
+		ur.Upper.Sub(lr.Upper),
+	}
+	// TODO(dh): if we don't truncate lengths to 0 we might be able to
+	// easily detect slices with high < low. we'd need to treat -∞
+	// specially, though.
+	for i, l := range ls {
+		if l.Sign() == -1 {
+			ls[i] = NewZ(0)
+		}
+	}
+
+	return SliceInterval{
+		Length: NewIntInterval(MinZ(ls...), MaxZ(ls...)),
+	}
+}
+func (c *ArraySliceConstraint) Eval(g *Graph) Range {
+	lr := NewIntInterval(NewZ(0), NewZ(0))
+	if c.Lower != nil {
+		lr = g.Range(c.Lower).(IntInterval)
+	}
+	var l int64
+	switch typ := c.X.Type().(type) {
+	case *types.Array:
+		l = typ.Len()
+	case *types.Pointer:
+		l = typ.Elem().(*types.Array).Len()
+	}
+	ur := NewIntInterval(NewZ(l), NewZ(l))
+	if c.Upper != nil {
+		ur = g.Range(c.Upper).(IntInterval)
+	}
+	if !lr.IsKnown() || !ur.IsKnown() {
+		return SliceInterval{}
+	}
+
+	ls := []Z{
+		ur.Lower.Sub(lr.Lower),
+		ur.Upper.Sub(lr.Lower),
+		ur.Lower.Sub(lr.Upper),
+		ur.Upper.Sub(lr.Upper),
+	}
+	// TODO(dh): if we don't truncate lengths to 0 we might be able to
+	// easily detect slices with high < low. we'd need to treat -∞
+	// specially, though.
+	for i, l := range ls {
+		if l.Sign() == -1 {
+			ls[i] = NewZ(0)
+		}
+	}
+
+	return SliceInterval{
+		Length: NewIntInterval(MinZ(ls...), MaxZ(ls...)),
+	}
+}
+func (c *SliceIntersectionConstraint) Eval(g *Graph) Range {
+	xi := g.Range(c.X).(SliceInterval)
+	if !xi.IsKnown() {
+		return c.I
+	}
+	return SliceInterval{
+		Length: xi.Length.Intersection(c.I),
+	}
+}
+func (c *SliceLengthConstraint) Eval(g *Graph) Range {
+	i := g.Range(c.X).(SliceInterval).Length
+	if !i.IsKnown() {
+		return NewIntInterval(NewZ(0), PInfinity)
+	}
+	return i
+}
+func (c *MakeSliceConstraint) Eval(g *Graph) Range {
+	i, ok := g.Range(c.Size).(IntInterval)
+	if !ok {
+		return SliceInterval{NewIntInterval(NewZ(0), PInfinity)}
+	}
+	if i.Lower.Sign() == -1 {
+		i.Lower = NewZ(0)
+	}
+	return SliceInterval{i}
+}
+func (c *SliceIntervalConstraint) Eval(*Graph) Range { return SliceInterval{c.I} }

vendor/honnef.co/go/tools/staticcheck/vrp/string.go

@@ -0,0 +1,258 @@
+package vrp
+
+import (
+	"fmt"
+	"go/token"
+	"go/types"
+
+	"honnef.co/go/tools/ssa"
+)
+
+type StringInterval struct {
+	Length IntInterval
+}
+
+func (s StringInterval) Union(other Range) Range {
+	i, ok := other.(StringInterval)
+	if !ok {
+		i = StringInterval{EmptyIntInterval}
+	}
+	if s.Length.Empty() || !s.Length.IsKnown() {
+		return i
+	}
+	if i.Length.Empty() || !i.Length.IsKnown() {
+		return s
+	}
+	return StringInterval{
+		Length: s.Length.Union(i.Length).(IntInterval),
+	}
+}
+
+func (s StringInterval) String() string {
+	return s.Length.String()
+}
+
+func (s StringInterval) IsKnown() bool {
+	return s.Length.IsKnown()
+}
+
+type StringSliceConstraint struct {
+	aConstraint
+	X     ssa.Value
+	Lower ssa.Value
+	Upper ssa.Value
+}
+
+type StringIntersectionConstraint struct {
+	aConstraint
+	ranges   Ranges
+	A        ssa.Value
+	B        ssa.Value
+	Op       token.Token
+	I        IntInterval
+	resolved bool
+}
+
+type StringConcatConstraint struct {
+	aConstraint
+	A ssa.Value
+	B ssa.Value
+}
+
+type StringLengthConstraint struct {
+	aConstraint
+	X ssa.Value
+}
+
+type StringIntervalConstraint struct {
+	aConstraint
+	I IntInterval
+}
+
+func NewStringSliceConstraint(x, lower, upper, y ssa.Value) Constraint {
+	return &StringSliceConstraint{NewConstraint(y), x, lower, upper}
+}
+func NewStringIntersectionConstraint(a, b ssa.Value, op token.Token, ranges Ranges, y ssa.Value) Constraint {
+	return &StringIntersectionConstraint{
+		aConstraint: NewConstraint(y),
+		ranges:      ranges,
+		A:           a,
+		B:           b,
+		Op:          op,
+	}
+}
+func NewStringConcatConstraint(a, b, y ssa.Value) Constraint {
+	return &StringConcatConstraint{NewConstraint(y), a, b}
+}
+func NewStringLengthConstraint(x ssa.Value, y ssa.Value) Constraint {
+	return &StringLengthConstraint{NewConstraint(y), x}
+}
+func NewStringIntervalConstraint(i IntInterval, y ssa.Value) Constraint {
+	return &StringIntervalConstraint{NewConstraint(y), i}
+}
+
+func (c *StringSliceConstraint) Operands() []ssa.Value {
+	vs := []ssa.Value{c.X}
+	if c.Lower != nil {
+		vs = append(vs, c.Lower)
+	}
+	if c.Upper != nil {
+		vs = append(vs, c.Upper)
+	}
+	return vs
+}
+func (c *StringIntersectionConstraint) Operands() []ssa.Value { return []ssa.Value{c.A} }
+func (c StringConcatConstraint) Operands() []ssa.Value        { return []ssa.Value{c.A, c.B} }
+func (c *StringLengthConstraint) Operands() []ssa.Value       { return []ssa.Value{c.X} }
+func (s *StringIntervalConstraint) Operands() []ssa.Value     { return nil }
+
+func (c *StringSliceConstraint) String() string {
+	var lname, uname string
+	if c.Lower != nil {
+		lname = c.Lower.Name()
+	}
+	if c.Upper != nil {
+		uname = c.Upper.Name()
+	}
+	return fmt.Sprintf("%s[%s:%s]", c.X.Name(), lname, uname)
+}
+func (c *StringIntersectionConstraint) String() string {
+	return fmt.Sprintf("%s = %s %s %s (%t branch)", c.Y().Name(), c.A.Name(), c.Op, c.B.Name(), c.Y().(*ssa.Sigma).Branch)
+}
+func (c StringConcatConstraint) String() string {
+	return fmt.Sprintf("%s = %s + %s", c.Y().Name(), c.A.Name(), c.B.Name())
+}
+func (c *StringLengthConstraint) String() string {
+	return fmt.Sprintf("%s = len(%s)", c.Y().Name(), c.X.Name())
+}
+func (c *StringIntervalConstraint) String() string { return fmt.Sprintf("%s = %s", c.Y().Name(), c.I) }
+
+func (c *StringSliceConstraint) Eval(g *Graph) Range {
+	lr := NewIntInterval(NewZ(0), NewZ(0))
+	if c.Lower != nil {
+		lr = g.Range(c.Lower).(IntInterval)
+	}
+	ur := g.Range(c.X).(StringInterval).Length
+	if c.Upper != nil {
+		ur = g.Range(c.Upper).(IntInterval)
+	}
+	if !lr.IsKnown() || !ur.IsKnown() {
+		return StringInterval{}
+	}
+
+	ls := []Z{
+		ur.Lower.Sub(lr.Lower),
+		ur.Upper.Sub(lr.Lower),
+		ur.Lower.Sub(lr.Upper),
+		ur.Upper.Sub(lr.Upper),
+	}
+	// TODO(dh): if we don't truncate lengths to 0 we might be able to
+	// easily detect slices with high < low. we'd need to treat -∞
+	// specially, though.
+	for i, l := range ls {
+		if l.Sign() == -1 {
+			ls[i] = NewZ(0)
+		}
+	}
+
+	return StringInterval{
+		Length: NewIntInterval(MinZ(ls...), MaxZ(ls...)),
+	}
+}
+func (c *StringIntersectionConstraint) Eval(g *Graph) Range {
+	var l IntInterval
+	switch r := g.Range(c.A).(type) {
+	case StringInterval:
+		l = r.Length
+	case IntInterval:
+		l = r
+	}
+
+	if !l.IsKnown() {
+		return StringInterval{c.I}
+	}
+	return StringInterval{
+		Length: l.Intersection(c.I),
+	}
+}
+func (c StringConcatConstraint) Eval(g *Graph) Range {
+	i1, i2 := g.Range(c.A).(StringInterval), g.Range(c.B).(StringInterval)
+	if !i1.Length.IsKnown() || !i2.Length.IsKnown() {
+		return StringInterval{}
+	}
+	return StringInterval{
+		Length: i1.Length.Add(i2.Length),
+	}
+}
+func (c *StringLengthConstraint) Eval(g *Graph) Range {
+	i := g.Range(c.X).(StringInterval).Length
+	if !i.IsKnown() {
+		return NewIntInterval(NewZ(0), PInfinity)
+	}
+	return i
+}
+func (c *StringIntervalConstraint) Eval(*Graph) Range { return StringInterval{c.I} }
+
+func (c *StringIntersectionConstraint) Futures() []ssa.Value {
+	return []ssa.Value{c.B}
+}
+
+func (c *StringIntersectionConstraint) Resolve() {
+	if (c.A.Type().Underlying().(*types.Basic).Info() & types.IsString) != 0 {
+		// comparing two strings
+		r, ok := c.ranges[c.B].(StringInterval)
+		if !ok {
+			c.I = NewIntInterval(NewZ(0), PInfinity)
+			return
+		}
+		switch c.Op {
+		case token.EQL:
+			c.I = r.Length
+		case token.GTR, token.GEQ:
+			c.I = NewIntInterval(r.Length.Lower, PInfinity)
+		case token.LSS, token.LEQ:
+			c.I = NewIntInterval(NewZ(0), r.Length.Upper)
+		case token.NEQ:
+		default:
+			panic("unsupported op " + c.Op.String())
+		}
+	} else {
+		r, ok := c.ranges[c.B].(IntInterval)
+		if !ok {
+			c.I = NewIntInterval(NewZ(0), PInfinity)
+			return
+		}
+		// comparing two lengths
+		switch c.Op {
+		case token.EQL:
+			c.I = r
+		case token.GTR:
+			c.I = NewIntInterval(r.Lower.Add(NewZ(1)), PInfinity)
+		case token.GEQ:
+			c.I = NewIntInterval(r.Lower, PInfinity)
+		case token.LSS:
+			c.I = NewIntInterval(NInfinity, r.Upper.Sub(NewZ(1)))
+		case token.LEQ:
+			c.I = NewIntInterval(NInfinity, r.Upper)
+		case token.NEQ:
+		default:
+			panic("unsupported op " + c.Op.String())
+		}
+	}
+}
+
+func (c *StringIntersectionConstraint) IsKnown() bool {
+	return c.I.IsKnown()
+}
+
+func (c *StringIntersectionConstraint) MarkUnresolved() {
+	c.resolved = false
+}
+
+func (c *StringIntersectionConstraint) MarkResolved() {
+	c.resolved = true
+}
+
+func (c *StringIntersectionConstraint) IsResolved() bool {
+	return c.resolved
+}