all: update vendored golang.org/x/tools

Pull in CL 358034 (and some more changes with passing tests) with:

	go get -d golang.org/x/tools@f916b54
	go mod tidy
	go mod vendor

This teaches x/tools/cmd/bundle and the package loader it uses about
the new export data version.

Fixes #49159.

Change-Id: Icc36e77e602b1cd2da03708f20d05a66fcf693cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/358620
Trust: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

src/cmd/go.mod

@@ -8,7 +8,7 @@ require (
 	golang.org/x/mod v0.5.1-0.20210913215816-37dd6891021a
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
 	golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b
-	golang.org/x/tools v0.1.8-0.20211011152358-18fa84021695
+	golang.org/x/tools v0.1.8-0.20211025211149-f916b54a1784
 )
 
 require (

src/cmd/go.sum

@@ -18,7 +18,7 @@ golang.org/x/sys v0.0.0-20210831042530-f4d43177bf5e h1:XMgFehsDnnLGtjvjOfqWSUzt0
 golang.org/x/sys v0.0.0-20210831042530-f4d43177bf5e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b h1:9zKuko04nR4gjZ4+DNjHqRlAJqbJETHwiNKDqTfOjfE=
 golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
-golang.org/x/tools v0.1.8-0.20211011152358-18fa84021695 h1:H+g8CC6T05IOoW6fXaWvb5N3XBYQElWwgDS/7Yxg8dU=
-golang.org/x/tools v0.1.8-0.20211011152358-18fa84021695/go.mod h1:LGqMHiF4EqQNHR1JncWGqT5BVaXmza+X+BDGol+dOxo=
+golang.org/x/tools v0.1.8-0.20211025211149-f916b54a1784 h1:+xP+QoP2SEPgbn+07I/yJTzP+gavj0XKGS6+JU5tlck=
+golang.org/x/tools v0.1.8-0.20211025211149-f916b54a1784/go.mod h1:LGqMHiF4EqQNHR1JncWGqT5BVaXmza+X+BDGol+dOxo=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

src/cmd/vendor/golang.org/x/tools/go/analysis/passes/composite/composite.go

@@ -14,6 +14,7 @@ import (
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/analysis/passes/inspect"
 	"golang.org/x/tools/go/ast/inspector"
+	"golang.org/x/tools/internal/typeparams"
 )
 
 const Doc = `check for unkeyed composite literals
@@ -67,41 +68,52 @@ func run(pass *analysis.Pass) (interface{}, error) {
 			// skip whitelisted types
 			return
 		}
-		under := typ.Underlying()
-		for {
-			ptr, ok := under.(*types.Pointer)
-			if !ok {
-				break
+		terms, err := typeparams.StructuralTerms(typ)
+		if err != nil {
+			return // invalid type
+		}
+		for _, term := range terms {
+			under := deref(term.Type().Underlying())
+			if _, ok := under.(*types.Struct); !ok {
+				// skip non-struct composite literals
+				continue
 			}
-			under = ptr.Elem().Underlying()
-		}
-		if _, ok := under.(*types.Struct); !ok {
-			// skip non-struct composite literals
-			return
-		}
-		if isLocalType(pass, typ) {
-			// allow unkeyed locally defined composite literal
-			return
-		}
-
-		// check if the CompositeLit contains an unkeyed field
-		allKeyValue := true
-		for _, e := range cl.Elts {
-			if _, ok := e.(*ast.KeyValueExpr); !ok {
-				allKeyValue = false
-				break
+			if isLocalType(pass, term.Type()) {
+				// allow unkeyed locally defined composite literal
+				continue
 			}
-		}
-		if allKeyValue {
-			// all the composite literal fields are keyed
+
+			// check if the CompositeLit contains an unkeyed field
+			allKeyValue := true
+			for _, e := range cl.Elts {
+				if _, ok := e.(*ast.KeyValueExpr); !ok {
+					allKeyValue = false
+					break
+				}
+			}
+			if allKeyValue {
+				// all the composite literal fields are keyed
+				continue
+			}
+
+			pass.ReportRangef(cl, "%s composite literal uses unkeyed fields", typeName)
 			return
 		}
-
-		pass.ReportRangef(cl, "%s composite literal uses unkeyed fields", typeName)
 	})
 	return nil, nil
 }
 
+func deref(typ types.Type) types.Type {
+	for {
+		ptr, ok := typ.(*types.Pointer)
+		if !ok {
+			break
+		}
+		typ = ptr.Elem().Underlying()
+	}
+	return typ
+}
+
 func isLocalType(pass *analysis.Pass, typ types.Type) bool {
 	switch x := typ.(type) {
 	case *types.Struct:
@@ -112,6 +124,8 @@ func isLocalType(pass *analysis.Pass, typ types.Type) bool {
 	case *types.Named:
 		// names in package foo are local to foo_test too
 		return strings.TrimSuffix(x.Obj().Pkg().Path(), "_test") == strings.TrimSuffix(pass.Pkg.Path(), "_test")
+	case *typeparams.TypeParam:
+		return strings.TrimSuffix(x.Obj().Pkg().Path(), "_test") == strings.TrimSuffix(pass.Pkg.Path(), "_test")
 	}
 	return false
 }

src/cmd/vendor/golang.org/x/tools/go/analysis/passes/printf/printf.go

@@ -834,8 +834,9 @@ func okPrintfArg(pass *analysis.Pass, call *ast.CallExpr, state *formatState) (o
 	}
 
 	// Could current arg implement fmt.Formatter?
+	// Skip check for the %w verb, which requires an error.
 	formatter := false
-	if state.argNum < len(call.Args) {
+	if v.typ != argError && state.argNum < len(call.Args) {
 		if tv, ok := pass.TypesInfo.Types[call.Args[state.argNum]]; ok {
 			formatter = isFormatter(tv.Type)
 		}

src/cmd/vendor/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go

@@ -51,6 +51,7 @@ import (
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/analysis/internal/analysisflags"
 	"golang.org/x/tools/go/analysis/internal/facts"
+	"golang.org/x/tools/internal/typeparams"
 )
 
 // A Config describes a compilation unit to be analyzed.
@@ -233,6 +234,8 @@ func run(fset *token.FileSet, cfg *Config, analyzers []*analysis.Analyzer) ([]re
 		Scopes:     make(map[ast.Node]*types.Scope),
 		Selections: make(map[*ast.SelectorExpr]*types.Selection),
 	}
+	typeparams.InitInstanceInfo(info)
+
 	pkg, err := tc.Check(cfg.ImportPath, fset, files, info)
 	if err != nil {
 		if cfg.SucceedOnTypecheckFailure {

src/cmd/vendor/golang.org/x/tools/internal/typeparams/normalize.go

@@ -0,0 +1,212 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package typeparams
+
+import (
+	"errors"
+	"fmt"
+	"go/types"
+	"os"
+	"strings"
+)
+
+//go:generate go run copytermlist.go
+
+const debug = false
+
+// NormalizeInterface returns the normal form of the interface iface, or nil if iface
+// has an empty type set (i.e. there are no types that satisfy iface). If the
+// resulting interface is non-nil, it will be identical to iface.
+//
+// An error is returned if the interface type is invalid, or too complicated to
+// reasonably normalize (for example, contains unions with more than a hundred
+// terms).
+//
+// An interface is in normal form if and only if:
+//   - it has 0 or 1 embedded types.
+//   - its embedded type is either a types.Union or has a concrete
+//     (non-interface) underlying type
+//   - if the embedded type is a union, each term of the union has a concrete
+//     underlying type, and no terms may be removed without changing the type set
+//     of the interface
+func NormalizeInterface(iface *types.Interface) (*types.Interface, error) {
+	var methods []*types.Func
+	for i := 0; i < iface.NumMethods(); i++ {
+		methods = append(methods, iface.Method(i))
+	}
+	var embeddeds []types.Type
+	tset, err := computeTermSet(iface, make(map[types.Type]*termSet), 0)
+	if err != nil {
+		return nil, err
+	}
+	switch {
+	case tset.terms.isEmpty():
+		// Special case: as documented
+		return nil, nil
+
+	case tset.terms.isAll():
+		// No embeddeds.
+
+	case len(tset.terms) == 1:
+		if !tset.terms[0].tilde {
+			embeddeds = append(embeddeds, tset.terms[0].typ)
+			break
+		}
+		fallthrough
+	default:
+		var terms []*Term
+		for _, term := range tset.terms {
+			terms = append(terms, NewTerm(term.tilde, term.typ))
+		}
+		embeddeds = append(embeddeds, NewUnion(terms))
+	}
+
+	return types.NewInterfaceType(methods, embeddeds), nil
+}
+
+var ErrEmptyTypeSet = errors.New("empty type set")
+
+// StructuralTerms returns the normalized structural type restrictions of a
+// type, if any. For types that are not type parameters, it returns term slice
+// containing a single non-tilde term holding the given type. For type
+// parameters, it returns the normalized term list of the type parameter's
+// constraint. See NormalizeInterface for more information on the normal form
+// of a constraint interface.
+//
+// StructuralTerms returns an error if the structural term list cannot be
+// computed. If the type set of typ is empty, it returns ErrEmptyTypeSet.
+func StructuralTerms(typ types.Type) ([]*Term, error) {
+	switch typ := typ.(type) {
+	case *TypeParam:
+		iface, _ := typ.Constraint().(*types.Interface)
+		if iface == nil {
+			return nil, fmt.Errorf("constraint is %T, not *types.Interface", typ)
+		}
+		tset, err := computeTermSet(iface, make(map[types.Type]*termSet), 0)
+		if err != nil {
+			return nil, err
+		}
+		if tset.terms.isEmpty() {
+			return nil, ErrEmptyTypeSet
+		}
+		if tset.terms.isAll() {
+			return nil, nil
+		}
+		var terms []*Term
+		for _, term := range tset.terms {
+			terms = append(terms, NewTerm(term.tilde, term.typ))
+		}
+		return terms, nil
+	default:
+		return []*Term{NewTerm(false, typ)}, nil
+	}
+}
+
+// A termSet holds the normalized set of terms for a given type.
+//
+// The name termSet is intentionally distinct from 'type set': a type set is
+// all types that implement a type (and includes method restrictions), whereas
+// a term set just represents the structural restrictions on a type.
+type termSet struct {
+	complete bool
+	terms    termlist
+}
+
+func indentf(depth int, format string, args ...interface{}) {
+	fmt.Fprintf(os.Stderr, strings.Repeat(".", depth)+format+"\n", args...)
+}
+
+func computeTermSet(t types.Type, seen map[types.Type]*termSet, depth int) (res *termSet, err error) {
+	if t == nil {
+		panic("nil type")
+	}
+
+	if debug {
+		indentf(depth, "%s", t.String())
+		defer func() {
+			if err != nil {
+				indentf(depth, "=> %s", err)
+			} else {
+				indentf(depth, "=> %s", res.terms.String())
+			}
+		}()
+	}
+
+	const maxTermCount = 100
+	if tset, ok := seen[t]; ok {
+		if !tset.complete {
+			return nil, fmt.Errorf("cycle detected in the declaration of %s", t)
+		}
+		return tset, nil
+	}
+
+	// Mark the current type as seen to avoid infinite recursion.
+	tset := new(termSet)
+	defer func() {
+		tset.complete = true
+	}()
+	seen[t] = tset
+
+	switch u := t.Underlying().(type) {
+	case *types.Interface:
+		// The term set of an interface is the intersection of the term sets of its
+		// embedded types.
+		tset.terms = allTermlist
+		for i := 0; i < u.NumEmbeddeds(); i++ {
+			embedded := u.EmbeddedType(i)
+			if _, ok := embedded.Underlying().(*TypeParam); ok {
+				return nil, fmt.Errorf("invalid embedded type %T", embedded)
+			}
+			tset2, err := computeTermSet(embedded, seen, depth+1)
+			if err != nil {
+				return nil, err
+			}
+			tset.terms = tset.terms.intersect(tset2.terms)
+		}
+	case *Union:
+		// The term set of a union is the union of term sets of its terms.
+		tset.terms = nil
+		for i := 0; i < u.Len(); i++ {
+			t := u.Term(i)
+			var terms termlist
+			switch t.Type().Underlying().(type) {
+			case *types.Interface:
+				tset2, err := computeTermSet(t.Type(), seen, depth+1)
+				if err != nil {
+					return nil, err
+				}
+				terms = tset2.terms
+			case *TypeParam, *Union:
+				// A stand-alone type parameter or union is not permitted as union
+				// term.
+				return nil, fmt.Errorf("invalid union term %T", t)
+			default:
+				if t.Type() == types.Typ[types.Invalid] {
+					continue
+				}
+				terms = termlist{{t.Tilde(), t.Type()}}
+			}
+			tset.terms = tset.terms.union(terms)
+			if len(tset.terms) > maxTermCount {
+				return nil, fmt.Errorf("exceeded max term count %d", maxTermCount)
+			}
+		}
+	case *TypeParam:
+		panic("unreachable")
+	default:
+		// For all other types, the term set is just a single non-tilde term
+		// holding the type itself.
+		if u != types.Typ[types.Invalid] {
+			tset.terms = termlist{{false, t}}
+		}
+	}
+	return tset, nil
+}
+
+// under is a facade for the go/types internal function of the same name. It is
+// used by typeterm.go.
+func under(t types.Type) types.Type {
+	return t.Underlying()
+}

src/cmd/vendor/golang.org/x/tools/internal/typeparams/termlist.go

@@ -0,0 +1,172 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by copytermlist.go DO NOT EDIT.
+
+package typeparams
+
+import (
+	"bytes"
+	"go/types"
+)
+
+// A termlist represents the type set represented by the union
+// t1 ∪ y2 ∪ ... tn of the type sets of the terms t1 to tn.
+// A termlist is in normal form if all terms are disjoint.
+// termlist operations don't require the operands to be in
+// normal form.
+type termlist []*term
+
+// allTermlist represents the set of all types.
+// It is in normal form.
+var allTermlist = termlist{new(term)}
+
+// String prints the termlist exactly (without normalization).
+func (xl termlist) String() string {
+	if len(xl) == 0 {
+		return "∅"
+	}
+	var buf bytes.Buffer
+	for i, x := range xl {
+		if i > 0 {
+			buf.WriteString(" ∪ ")
+		}
+		buf.WriteString(x.String())
+	}
+	return buf.String()
+}
+
+// isEmpty reports whether the termlist xl represents the empty set of types.
+func (xl termlist) isEmpty() bool {
+	// If there's a non-nil term, the entire list is not empty.
+	// If the termlist is in normal form, this requires at most
+	// one iteration.
+	for _, x := range xl {
+		if x != nil {
+			return false
+		}
+	}
+	return true
+}
+
+// isAll reports whether the termlist xl represents the set of all types.
+func (xl termlist) isAll() bool {
+	// If there's a 𝓤 term, the entire list is 𝓤.
+	// If the termlist is in normal form, this requires at most
+	// one iteration.
+	for _, x := range xl {
+		if x != nil && x.typ == nil {
+			return true
+		}
+	}
+	return false
+}
+
+// norm returns the normal form of xl.
+func (xl termlist) norm() termlist {
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	used := make([]bool, len(xl))
+	var rl termlist
+	for i, xi := range xl {
+		if xi == nil || used[i] {
+			continue
+		}
+		for j := i + 1; j < len(xl); j++ {
+			xj := xl[j]
+			if xj == nil || used[j] {
+				continue
+			}
+			if u1, u2 := xi.union(xj); u2 == nil {
+				// If we encounter a 𝓤 term, the entire list is 𝓤.
+				// Exit early.
+				// (Note that this is not just an optimization;
+				// if we continue, we may end up with a 𝓤 term
+				// and other terms and the result would not be
+				// in normal form.)
+				if u1.typ == nil {
+					return allTermlist
+				}
+				xi = u1
+				used[j] = true // xj is now unioned into xi - ignore it in future iterations
+			}
+		}
+		rl = append(rl, xi)
+	}
+	return rl
+}
+
+// If the type set represented by xl is specified by a single (non-𝓤) term,
+// structuralType returns that type. Otherwise it returns nil.
+func (xl termlist) structuralType() types.Type {
+	if nl := xl.norm(); len(nl) == 1 {
+		return nl[0].typ // if nl.isAll() then typ is nil, which is ok
+	}
+	return nil
+}
+
+// union returns the union xl ∪ yl.
+func (xl termlist) union(yl termlist) termlist {
+	return append(xl, yl...).norm()
+}
+
+// intersect returns the intersection xl ∩ yl.
+func (xl termlist) intersect(yl termlist) termlist {
+	if xl.isEmpty() || yl.isEmpty() {
+		return nil
+	}
+
+	// Quadratic algorithm, but good enough for now.
+	// TODO(gri) fix asymptotic performance
+	var rl termlist
+	for _, x := range xl {
+		for _, y := range yl {
+			if r := x.intersect(y); r != nil {
+				rl = append(rl, r)
+			}
+		}
+	}
+	return rl.norm()
+}
+
+// equal reports whether xl and yl represent the same type set.
+func (xl termlist) equal(yl termlist) bool {
+	// TODO(gri) this should be more efficient
+	return xl.subsetOf(yl) && yl.subsetOf(xl)
+}
+
+// includes reports whether t ∈ xl.
+func (xl termlist) includes(t types.Type) bool {
+	for _, x := range xl {
+		if x.includes(t) {
+			return true
+		}
+	}
+	return false
+}
+
+// supersetOf reports whether y ⊆ xl.
+func (xl termlist) supersetOf(y *term) bool {
+	for _, x := range xl {
+		if y.subsetOf(x) {
+			return true
+		}
+	}
+	return false
+}
+
+// subsetOf reports whether xl ⊆ yl.
+func (xl termlist) subsetOf(yl termlist) bool {
+	if yl.isEmpty() {
+		return xl.isEmpty()
+	}
+
+	// each term x of xl must be a subset of yl
+	for _, x := range xl {
+		if !yl.supersetOf(x) {
+			return false // x is not a subset yl
+		}
+	}
+	return true
+}

src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams_go117.go

@@ -132,6 +132,15 @@ func IsMethodSet(*types.Interface) bool {
 	return true
 }
 
+// IsImplicit returns false, as no interfaces are implicit at this Go version.
+func IsImplicit(*types.Interface) bool {
+	return false
+}
+
+// MarkImplicit does nothing, because this Go version does not have implicit
+// interfaces.
+func MarkImplicit(*types.Interface) {}
+
 // ForNamed returns an empty type parameter list, as type parameters are not
 // supported at this Go version.
 func ForNamed(*types.Named) *TypeParamList {
@@ -155,19 +164,25 @@ func NamedTypeOrigin(named *types.Named) types.Type {
 	return named
 }
 
-// Term is a placeholder type, as type parameters are not supported at this Go
-// version. Its methods panic on use.
-type Term struct{}
+// Term holds information about a structural type restriction.
+type Term struct {
+	tilde bool
+	typ   types.Type
+}
 
-func (*Term) Tilde() bool            { unsupported(); return false }
-func (*Term) Type() types.Type       { unsupported(); return nil }
-func (*Term) String() string         { unsupported(); return "" }
-func (*Term) Underlying() types.Type { unsupported(); return nil }
+func (m *Term) Tilde() bool      { return m.tilde }
+func (m *Term) Type() types.Type { return m.typ }
+func (m *Term) String() string {
+	pre := ""
+	if m.tilde {
+		pre = "~"
+	}
+	return pre + m.typ.String()
+}
 
 // NewTerm is unsupported at this Go version, and panics.
 func NewTerm(tilde bool, typ types.Type) *Term {
-	unsupported()
-	return nil
+	return &Term{tilde, typ}
 }
 
 // Union is a placeholder type, as type parameters are not supported at this Go
@@ -186,9 +201,16 @@ func NewUnion(terms []*Term) *Union {
 // InitInstanceInfo is a noop at this Go version.
 func InitInstanceInfo(*types.Info) {}
 
-// GetInstance returns nothing, as type parameters are not supported at this Go
-// version.
-func GetInstance(*types.Info, *ast.Ident) (*TypeList, types.Type) { return nil, nil }
+// Instance is a placeholder type, as type parameters are not supported at this
+// Go version.
+type Instance struct {
+	TypeArgs *TypeList
+	Type     types.Type
+}
+
+// GetInstances returns a nil map, as type parameters are not supported at this
+// Go version.
+func GetInstances(info *types.Info) map[*ast.Ident]Instance { return nil }
 
 // Context is a placeholder type, as type parameters are not supported at
 // this Go version.

src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeparams_go118.go

@@ -125,6 +125,16 @@ func IsMethodSet(iface *types.Interface) bool {
 	return iface.IsMethodSet()
 }
 
+// IsImplicit calls iface.IsImplicit().
+func IsImplicit(iface *types.Interface) bool {
+	return iface.IsImplicit()
+}
+
+// MarkImplicit calls iface.MarkImplicit().
+func MarkImplicit(iface *types.Interface) {
+	iface.MarkImplicit()
+}
+
 // ForNamed extracts the (possibly empty) type parameter object list from
 // named.
 func ForNamed(named *types.Named) *TypeParamList {
@@ -169,15 +179,12 @@ func InitInstanceInfo(info *types.Info) {
 	info.Instances = make(map[*ast.Ident]types.Instance)
 }
 
-// GetInstance extracts information about the instantiation occurring at the
-// identifier id. id should be the identifier denoting a parameterized type or
-// function in an instantiation expression or function call.
-func GetInstance(info *types.Info, id *ast.Ident) (*TypeList, types.Type) {
-	if info.Instances != nil {
-		inf := info.Instances[id]
-		return inf.TypeArgs, inf.Type
-	}
-	return nil, nil
+// Instance is an alias for types.Instance.
+type Instance = types.Instance
+
+// GetInstances returns info.Instances.
+func GetInstances(info *types.Info) map[*ast.Ident]Instance {
+	return info.Instances
 }
 
 // Context is an alias for types.Context.

src/cmd/vendor/golang.org/x/tools/internal/typeparams/typeterm.go

@@ -0,0 +1,170 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Code generated by copytermlist.go DO NOT EDIT.
+
+package typeparams
+
+import "go/types"
+
+// A term describes elementary type sets:
+//
+//   ∅:  (*term)(nil)     == ∅                      // set of no types (empty set)
+//   𝓤:  &term{}          == 𝓤                      // set of all types (𝓤niverse)
+//   T:  &term{false, T}  == {T}                    // set of type T
+//  ~t:  &term{true, t}   == {t' | under(t') == t}  // set of types with underlying type t
+//
+type term struct {
+	tilde bool // valid if typ != nil
+	typ   types.Type
+}
+
+func (x *term) String() string {
+	switch {
+	case x == nil:
+		return "∅"
+	case x.typ == nil:
+		return "𝓤"
+	case x.tilde:
+		return "~" + x.typ.String()
+	default:
+		return x.typ.String()
+	}
+}
+
+// equal reports whether x and y represent the same type set.
+func (x *term) equal(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return x == y
+	case x.typ == nil || y.typ == nil:
+		return x.typ == y.typ
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	return x.tilde == y.tilde && types.Identical(x.typ, y.typ)
+}
+
+// union returns the union x ∪ y: zero, one, or two non-nil terms.
+func (x *term) union(y *term) (_, _ *term) {
+	// easy cases
+	switch {
+	case x == nil && y == nil:
+		return nil, nil // ∅ ∪ ∅ == ∅
+	case x == nil:
+		return y, nil // ∅ ∪ y == y
+	case y == nil:
+		return x, nil // x ∪ ∅ == x
+	case x.typ == nil:
+		return x, nil // 𝓤 ∪ y == 𝓤
+	case y.typ == nil:
+		return y, nil // x ∪ 𝓤 == 𝓤
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∪ ~t == ~t
+	// ~t ∪  T == ~t
+	//  T ∪ ~t == ~t
+	//  T ∪  T ==  T
+	if x.tilde || !y.tilde {
+		return x, nil
+	}
+	return y, nil
+}
+
+// intersect returns the intersection x ∩ y.
+func (x *term) intersect(y *term) *term {
+	// easy cases
+	switch {
+	case x == nil || y == nil:
+		return nil // ∅ ∩ y == ∅ and ∩ ∅ == ∅
+	case x.typ == nil:
+		return y // 𝓤 ∩ y == y
+	case y.typ == nil:
+		return x // x ∩ 𝓤 == x
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return nil // x ∩ y == ∅ if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ∩ ~t == ~t
+	// ~t ∩  T ==  T
+	//  T ∩ ~t ==  T
+	//  T ∩  T ==  T
+	if !x.tilde || y.tilde {
+		return x
+	}
+	return y
+}
+
+// includes reports whether t ∈ x.
+func (x *term) includes(t types.Type) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return false // t ∈ ∅ == false
+	case x.typ == nil:
+		return true // t ∈ 𝓤 == true
+	}
+	// ∅ ⊂ x ⊂ 𝓤
+
+	u := t
+	if x.tilde {
+		u = under(u)
+	}
+	return types.Identical(x.typ, u)
+}
+
+// subsetOf reports whether x ⊆ y.
+func (x *term) subsetOf(y *term) bool {
+	// easy cases
+	switch {
+	case x == nil:
+		return true // ∅ ⊆ y == true
+	case y == nil:
+		return false // x ⊆ ∅ == false since x != ∅
+	case y.typ == nil:
+		return true // x ⊆ 𝓤 == true
+	case x.typ == nil:
+		return false // 𝓤 ⊆ y == false since y != 𝓤
+	}
+	// ∅ ⊂ x, y ⊂ 𝓤
+
+	if x.disjoint(y) {
+		return false // x ⊆ y == false if x ∩ y == ∅
+	}
+	// x.typ == y.typ
+
+	// ~t ⊆ ~t == true
+	// ~t ⊆ T == false
+	//  T ⊆ ~t == true
+	//  T ⊆  T == true
+	return !x.tilde || y.tilde
+}
+
+// disjoint reports whether x ∩ y == ∅.
+// x.typ and y.typ must not be nil.
+func (x *term) disjoint(y *term) bool {
+	if debug && (x.typ == nil || y.typ == nil) {
+		panic("invalid argument(s)")
+	}
+	ux := x.typ
+	if y.tilde {
+		ux = under(ux)
+	}
+	uy := y.typ
+	if x.tilde {
+		uy = under(uy)
+	}
+	return !types.Identical(ux, uy)
+}

src/cmd/vendor/modules.txt

@@ -51,7 +51,7 @@ golang.org/x/sys/windows
 # golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b
 ## explicit; go 1.17
 golang.org/x/term
-# golang.org/x/tools v0.1.8-0.20211011152358-18fa84021695
+# golang.org/x/tools v0.1.8-0.20211025211149-f916b54a1784
 ## explicit; go 1.17
 golang.org/x/tools/cover
 golang.org/x/tools/go/analysis