Update go version

vendor/honnef.co/go/tools/internal/xtools-internal/astutil/clone.go

@@ -0,0 +1,71 @@
+// Copyright 2023 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 astutil
+
+import (
+	"go/ast"
+	"reflect"
+)
+
+// CloneNode returns a deep copy of a Node.
+// It omits pointers to ast.{Scope,Object} variables.
+func CloneNode[T ast.Node](n T) T {
+	return cloneNode(n).(T)
+}
+
+func cloneNode(n ast.Node) ast.Node {
+	var clone func(x reflect.Value) reflect.Value
+	set := func(dst, src reflect.Value) {
+		src = clone(src)
+		if src.IsValid() {
+			dst.Set(src)
+		}
+	}
+	clone = func(x reflect.Value) reflect.Value {
+		switch x.Kind() {
+		case reflect.Pointer:
+			if x.IsNil() {
+				return x
+			}
+			// Skip fields of types potentially involved in cycles.
+			switch x.Interface().(type) {
+			case *ast.Object, *ast.Scope:
+				return reflect.Zero(x.Type())
+			}
+			y := reflect.New(x.Type().Elem())
+			set(y.Elem(), x.Elem())
+			return y
+
+		case reflect.Struct:
+			y := reflect.New(x.Type()).Elem()
+			for i := 0; i < x.Type().NumField(); i++ {
+				set(y.Field(i), x.Field(i))
+			}
+			return y
+
+		case reflect.Slice:
+			if x.IsNil() {
+				return x
+			}
+			y := reflect.MakeSlice(x.Type(), x.Len(), x.Cap())
+			for i := 0; i < x.Len(); i++ {
+				set(y.Index(i), x.Index(i))
+			}
+			return y
+
+		case reflect.Interface:
+			y := reflect.New(x.Type()).Elem()
+			set(y, x.Elem())
+			return y
+
+		case reflect.Array, reflect.Chan, reflect.Func, reflect.Map, reflect.UnsafePointer:
+			panic(x) // unreachable in AST
+
+		default:
+			return x // bool, string, number
+		}
+	}
+	return clone(reflect.ValueOf(n)).Interface().(ast.Node)
+}

vendor/honnef.co/go/tools/internal/xtools-internal/astutil/comment.go

@@ -0,0 +1,143 @@
+// Copyright 2025 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 astutil
+
+import (
+	"go/ast"
+	"go/token"
+	"iter"
+	"sort"
+	"strings"
+)
+
+// Deprecation returns the paragraph of the doc comment that starts with the
+// conventional "Deprecation: " marker, as defined by
+// https://go.dev/wiki/Deprecated, or "" if the documented symbol is not
+// deprecated.
+func Deprecation(doc *ast.CommentGroup) string {
+	for p := range strings.SplitSeq(doc.Text(), "\n\n") {
+		// There is still some ambiguity for deprecation message. This function
+		// only returns the paragraph introduced by "Deprecated: ". More
+		// information related to the deprecation may follow in additional
+		// paragraphs, but the deprecation message should be able to stand on
+		// its own. See golang/go#38743.
+		if strings.HasPrefix(p, "Deprecated: ") {
+			return p
+		}
+	}
+	return ""
+}
+
+// -- plundered from the future (CL 605517, issue #68021) --
+
+// TODO(adonovan): replace with ast.Directive in go1.26 (#68021).
+// Beware of our local mods to handle analysistest
+// "want" comments on the same line.
+
+// A directive is a comment line with special meaning to the Go
+// toolchain or another tool. It has the form:
+//
+//	//tool:name args
+//
+// The "tool:" portion is missing for the three directives named
+// line, extern, and export.
+//
+// See https://go.dev/doc/comment#Syntax for details of Go comment
+// syntax and https://pkg.go.dev/cmd/compile#hdr-Compiler_Directives
+// for details of directives used by the Go compiler.
+type Directive struct {
+	Pos  token.Pos // of preceding "//"
+	Tool string
+	Name string
+	Args string // may contain internal spaces
+}
+
+// isDirective reports whether c is a comment directive.
+// This code is also in go/printer.
+func isDirective(c string) bool {
+	// "//line " is a line directive.
+	// "//extern " is for gccgo.
+	// "//export " is for cgo.
+	// (The // has been removed.)
+	if strings.HasPrefix(c, "line ") || strings.HasPrefix(c, "extern ") || strings.HasPrefix(c, "export ") {
+		return true
+	}
+
+	// "//[a-z0-9]+:[a-z0-9]"
+	// (The // has been removed.)
+	colon := strings.Index(c, ":")
+	if colon <= 0 || colon+1 >= len(c) {
+		return false
+	}
+	for i := 0; i <= colon+1; i++ {
+		if i == colon {
+			continue
+		}
+		b := c[i]
+		if !('a' <= b && b <= 'z' || '0' <= b && b <= '9') {
+			return false
+		}
+	}
+	return true
+}
+
+// Directives returns the directives within the comment.
+func Directives(g *ast.CommentGroup) (res []*Directive) {
+	if g != nil {
+		// Avoid (*ast.CommentGroup).Text() as it swallows directives.
+		for _, c := range g.List {
+			if len(c.Text) > 2 &&
+				c.Text[1] == '/' &&
+				c.Text[2] != ' ' &&
+				isDirective(c.Text[2:]) {
+
+				tool, nameargs, ok := strings.Cut(c.Text[2:], ":")
+				if !ok {
+					// Must be one of {line,extern,export}.
+					tool, nameargs = "", tool
+				}
+				name, args, _ := strings.Cut(nameargs, " ") // tab??
+				// Permit an additional line comment after the args, chiefly to support
+				// [golang.org/x/tools/go/analysis/analysistest].
+				args, _, _ = strings.Cut(args, "//")
+				res = append(res, &Directive{
+					Pos:  c.Slash,
+					Tool: tool,
+					Name: name,
+					Args: strings.TrimSpace(args),
+				})
+			}
+		}
+	}
+	return
+}
+
+// Comments returns an iterator over the comments overlapping the specified interval.
+// Comments are sorted by position in the file, so we can use binary search.
+func Comments(file *ast.File, start, end token.Pos) iter.Seq[*ast.Comment] {
+	return func(yield func(*ast.Comment) bool) {
+		// Find the first comment group that overlaps the range.
+		i := sort.Search(len(file.Comments), func(i int) bool {
+			return file.Comments[i].End() >= start
+		})
+		for _, cg := range file.Comments[i:] {
+			if cg.Pos() > end {
+				return
+			}
+			// Find the first comment in the group that overlaps the range.
+			j := sort.Search(len(cg.List), func(j int) bool {
+				return cg.List[j].End() >= start
+			})
+			for _, co := range cg.List[j:] {
+				if co.Pos() > end {
+					return
+				}
+				if !yield(co) {
+					return
+				}
+			}
+		}
+	}
+}

vendor/honnef.co/go/tools/internal/xtools-internal/astutil/cursor.go

@@ -0,0 +1,38 @@
+// Copyright 2026 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 astutil
+
+import (
+	"go/ast"
+
+	"golang.org/x/tools/go/ast/edge"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+// UnparenCursor returns the cursor for an expression with any
+// enclosing parentheses removed, similar to [ast.Unparen].
+// It is often prudent to call this before switching on the
+// type of cur.Node().
+//
+// See also [UnparenEnclosingCursor].
+func UnparenCursor(cur inspector.Cursor) inspector.Cursor {
+	for is[*ast.ParenExpr](cur) {
+		cur, _ = cur.FirstChild()
+	}
+	return cur
+}
+
+// UnparenEnclosingCursor returns the first element of
+// the [Cursor.Enclosing] sequence that is not itself enclosed
+// in parens. It is often prudent to call this before switching on
+// cur.ParentEdge().
+//
+// See also [UnparenCursor].
+func UnparenEnclosingCursor(cur inspector.Cursor) inspector.Cursor {
+	for cur.ParentEdgeKind() == edge.ParenExpr_X {
+		cur = cur.Parent()
+	}
+	return cur
+}

vendor/honnef.co/go/tools/internal/xtools-internal/astutil/equal.go

@@ -0,0 +1,107 @@
+// Copyright 2023 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 astutil
+
+import (
+	"go/ast"
+	"go/token"
+	"reflect"
+)
+
+// Equal reports whether two nodes are structurally equal,
+// ignoring fields of type [token.Pos], [ast.Object],
+// and [ast.Scope], and comments.
+//
+// The operands x and y may be nil.
+// A nil slice is not equal to an empty slice.
+//
+// The provided function determines whether two identifiers
+// should be considered identical.
+func Equal(x, y ast.Node, identical func(x, y *ast.Ident) bool) bool {
+	if x == nil || y == nil {
+		return x == y
+	}
+	return equal(reflect.ValueOf(x), reflect.ValueOf(y), identical)
+}
+
+// EqualSyntax reports whether x and y are equal.
+// Identifiers are considered equal if they are spelled the same.
+// Comments are ignored.
+func EqualSyntax(x, y ast.Expr) bool {
+	sameName := func(x, y *ast.Ident) bool { return x.Name == y.Name }
+	return Equal(x, y, sameName)
+}
+
+func equal(x, y reflect.Value, identical func(x, y *ast.Ident) bool) bool {
+	// Ensure types are the same
+	if x.Type() != y.Type() {
+		return false
+	}
+	switch x.Kind() {
+	case reflect.Pointer:
+		if x.IsNil() || y.IsNil() {
+			return x.IsNil() == y.IsNil()
+		}
+		switch t := x.Interface().(type) {
+		// Skip fields of types potentially involved in cycles.
+		case *ast.Object, *ast.Scope, *ast.CommentGroup:
+			return true
+		case *ast.Ident:
+			return identical(t, y.Interface().(*ast.Ident))
+		default:
+			return equal(x.Elem(), y.Elem(), identical)
+		}
+
+	case reflect.Interface:
+		if x.IsNil() || y.IsNil() {
+			return x.IsNil() == y.IsNil()
+		}
+		return equal(x.Elem(), y.Elem(), identical)
+
+	case reflect.Struct:
+		for i := range x.NumField() {
+			xf := x.Field(i)
+			yf := y.Field(i)
+			// Skip position fields.
+			if xpos, ok := xf.Interface().(token.Pos); ok {
+				ypos := yf.Interface().(token.Pos)
+				// Numeric value of a Pos is not significant but its "zeroness" is,
+				// because it is often significant, e.g. CallExpr.Variadic(Ellipsis), ChanType.Arrow.
+				if xpos.IsValid() != ypos.IsValid() {
+					return false
+				}
+			} else if !equal(xf, yf, identical) {
+				return false
+			}
+		}
+		return true
+
+	case reflect.Slice:
+		if x.IsNil() || y.IsNil() {
+			return x.IsNil() == y.IsNil()
+		}
+		if x.Len() != y.Len() {
+			return false
+		}
+		for i := range x.Len() {
+			if !equal(x.Index(i), y.Index(i), identical) {
+				return false
+			}
+		}
+		return true
+
+	case reflect.String:
+		return x.String() == y.String()
+
+	case reflect.Bool:
+		return x.Bool() == y.Bool()
+
+	case reflect.Int:
+		return x.Int() == y.Int()
+
+	default:
+		panic(x)
+	}
+}

vendor/honnef.co/go/tools/internal/xtools-internal/astutil/fields.go

@@ -0,0 +1,35 @@
+// Copyright 2024 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 astutil
+
+import (
+	"go/ast"
+	"iter"
+)
+
+// FlatFields 'flattens' an ast.FieldList, returning an iterator over each
+// (name, field) combination in the list. For unnamed fields, the identifier is
+// nil.
+func FlatFields(list *ast.FieldList) iter.Seq2[*ast.Ident, *ast.Field] {
+	return func(yield func(*ast.Ident, *ast.Field) bool) {
+		if list == nil {
+			return
+		}
+
+		for _, field := range list.List {
+			if len(field.Names) == 0 {
+				if !yield(nil, field) {
+					return
+				}
+			} else {
+				for _, name := range field.Names {
+					if !yield(name, field) {
+						return
+					}
+				}
+			}
+		}
+	}
+}

vendor/honnef.co/go/tools/internal/xtools-internal/astutil/purge.go

@@ -0,0 +1,93 @@
+// Copyright 2023 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 astutil provides various AST utility functions for gopls.
+package astutil
+
+import (
+	"bytes"
+	"go/scanner"
+	"go/token"
+)
+
+// PurgeFuncBodies returns a copy of src in which the contents of each
+// outermost {...} region have been deleted, except for struct and
+// interface type bodies and the bodies of length-elided array
+// literals ([...]T), whose element count is part of the type. It
+// includes function bodies, function-literal bodies, and the bodies
+// of slice, map, and explicitly-sized array composite literals (whose
+// contents don't affect the type of the enclosing declaration). This
+// reduces the amount of work required to parse the top-level
+// declarations.
+//
+// PurgeFuncBodies does not preserve newlines or position information.
+// Also, if the input is invalid, parsing the output of
+// PurgeFuncBodies may result in a different tree due to its effects
+// on parser error recovery.
+func PurgeFuncBodies(src []byte) []byte {
+	// Destroy the content of any {...}-bracketed regions that are
+	// not immediately preceded by a "struct" or "interface" token,
+	// and that are not the body of a length-elided array literal.
+	// That includes function bodies, switch/select bodies, and most
+	// composite literals; this will lead to non-void functions that
+	// don't have return statements, which of course is a type error,
+	// but that's ok.
+
+	var out bytes.Buffer
+	file := token.NewFileSet().AddFile("", -1, len(src))
+	var sc scanner.Scanner
+	sc.Init(file, src, nil, 0)
+	var prev token.Token
+	var cursor int         // last consumed src offset
+	var braces []token.Pos // stack of unclosed braces, or -1 for a region we preserve
+	var ellipsis bool      // saw "[...]" not yet consumed by a literal-body "{"
+	for {
+		pos, tok, _ := sc.Scan()
+		if tok == token.EOF {
+			break
+		}
+		switch tok {
+		case token.COMMENT:
+			// TODO(adonovan): opt: skip, to save an estimated 20% of time.
+
+		case token.SEMICOLON:
+			ellipsis = false
+
+		case token.RBRACK:
+			// "...]" occurs only in the array-type prefix of a
+			// composite literal; variadic "..." is followed by
+			// a type or ")", never "]".
+			if prev == token.ELLIPSIS {
+				ellipsis = true
+			}
+
+		case token.LBRACE:
+			if prev == token.STRUCT || prev == token.INTERFACE {
+				pos = -1 // type body: preserve (don't consume ellipsis)
+			} else if ellipsis {
+				pos = -1 // [...]T literal body: preserve
+				ellipsis = false
+			}
+			braces = append(braces, pos)
+
+		case token.RBRACE:
+			if last := len(braces) - 1; last >= 0 {
+				top := braces[last]
+				braces = braces[:last]
+				if top < 0 {
+					// preserve
+				} else if len(braces) == 0 { // toplevel only
+					// Delete {...} body.
+					start := file.Offset(top)
+					end := file.Offset(pos)
+					out.Write(src[cursor : start+len("{")])
+					cursor = end
+				}
+			}
+		}
+		prev = tok
+	}
+	out.Write(src[cursor:])
+	return out.Bytes()
+}

vendor/honnef.co/go/tools/internal/xtools-internal/astutil/stringlit.go

@@ -0,0 +1,103 @@
+// Copyright 2025 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 astutil
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"strconv"
+	"unicode/utf8"
+)
+
+// RangeInStringLiteral calculates the positional range within a string literal
+// corresponding to the specified start and end byte offsets within the logical string.
+func RangeInStringLiteral(lit *ast.BasicLit, start, end int) (Range, error) {
+	startPos, err := PosInStringLiteral(lit, start)
+	if err != nil {
+		return Range{}, fmt.Errorf("start: %v", err)
+	}
+	endPos, err := PosInStringLiteral(lit, end)
+	if err != nil {
+		return Range{}, fmt.Errorf("end: %v", err)
+	}
+	return Range{startPos, endPos}, nil
+}
+
+// PosInStringLiteral returns the position within a string literal
+// corresponding to the specified byte offset within the logical
+// string that it denotes.
+func PosInStringLiteral(lit *ast.BasicLit, offset int) (token.Pos, error) {
+	raw := lit.Value
+
+	value, err := strconv.Unquote(raw)
+	if err != nil {
+		return 0, err
+	}
+	if !(0 <= offset && offset <= len(value)) {
+		return 0, fmt.Errorf("invalid offset")
+	}
+
+	pos, _ := walkStringLiteral(lit, lit.End(), offset)
+	return pos, nil
+}
+
+// OffsetInStringLiteral returns the byte offset within the logical (unquoted)
+// string corresponding to the specified source position.
+func OffsetInStringLiteral(lit *ast.BasicLit, pos token.Pos) (int, error) {
+	if !NodeContainsPos(lit, pos) {
+		return 0, fmt.Errorf("invalid position")
+	}
+
+	raw := lit.Value
+
+	value, err := strconv.Unquote(raw)
+	if err != nil {
+		return 0, err
+	}
+
+	_, offset := walkStringLiteral(lit, pos, len(value))
+	return offset, nil
+}
+
+// walkStringLiteral iterates through the raw string literal to map between
+// a file position and a logical byte offset. It stops when it reaches
+// either the targetPos or the targetOffset.
+//
+// TODO(hxjiang): consider making an iterator.
+func walkStringLiteral(lit *ast.BasicLit, targetPos token.Pos, targetOffset int) (token.Pos, int) {
+	raw := lit.Value
+	norm := int(lit.End()-lit.Pos()) > len(lit.Value)
+
+	// remove quotes
+	quote := raw[0] // '"' or '`'
+	raw = raw[1 : len(raw)-1]
+
+	var (
+		i   = 0             // byte index within logical value
+		pos = lit.Pos() + 1 // position within literal
+	)
+
+	for raw != "" {
+		r, _, rest, _ := strconv.UnquoteChar(raw, quote) // can't fail
+		sz := len(raw) - len(rest)                       // length of literal char in raw bytes
+
+		nextPos := pos + token.Pos(sz)
+		if norm && r == '\n' {
+			nextPos++
+		}
+		nextI := i + utf8.RuneLen(r) // length of logical char in "cooked" bytes
+
+		if nextPos > targetPos || nextI > targetOffset {
+			break
+		}
+
+		raw = raw[sz:]
+		i = nextI
+		pos = nextPos
+	}
+
+	return pos, i
+}

vendor/honnef.co/go/tools/internal/xtools-internal/astutil/unpack.go

@@ -0,0 +1,61 @@
+// Copyright 2023 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 astutil
+
+import (
+	"go/ast"
+
+	"honnef.co/go/tools/internal/xtools-internal/typeparams"
+)
+
+// UnpackRecv unpacks a receiver type expression, reporting whether it is a
+// pointer receiver, along with the type name identifier and any receiver type
+// parameter identifiers.
+//
+// Copied (with modifications) from go/types.
+func UnpackRecv(rtyp ast.Expr) (ptr bool, rname *ast.Ident, tparams []*ast.Ident) {
+L: // unpack receiver type
+	// This accepts invalid receivers such as ***T and does not
+	// work for other invalid receivers, but we don't care. The
+	// validity of receiver expressions is checked elsewhere.
+	for {
+		switch t := rtyp.(type) {
+		case *ast.ParenExpr:
+			rtyp = t.X
+		case *ast.StarExpr:
+			ptr = true
+			rtyp = t.X
+		default:
+			break L
+		}
+	}
+
+	// unpack type parameters, if any
+	switch rtyp.(type) {
+	case *ast.IndexExpr, *ast.IndexListExpr:
+		var indices []ast.Expr
+		rtyp, _, indices, _ = typeparams.UnpackIndexExpr(rtyp)
+		for _, arg := range indices {
+			var par *ast.Ident
+			switch arg := arg.(type) {
+			case *ast.Ident:
+				par = arg
+			default:
+				// ignore errors
+			}
+			if par == nil {
+				par = &ast.Ident{NamePos: arg.Pos(), Name: "_"}
+			}
+			tparams = append(tparams, par)
+		}
+	}
+
+	// unpack receiver name
+	if name, _ := rtyp.(*ast.Ident); name != nil {
+		rname = name
+	}
+
+	return
+}

vendor/honnef.co/go/tools/internal/xtools-internal/astutil/util.go

@@ -0,0 +1,261 @@
+// Copyright 2025 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 astutil
+
+import (
+	"fmt"
+	"go/ast"
+	"go/printer"
+	"go/token"
+	"strings"
+
+	"golang.org/x/tools/go/ast/inspector"
+	"honnef.co/go/tools/internal/xtools-internal/moreiters"
+)
+
+// NodeContains reports whether the Pos/End range of node n encloses
+// the given range.
+//
+// It is inclusive of both end points, to allow hovering (etc) when
+// the cursor is immediately after a node.
+//
+// Like [NodeRange], it treats the range of an [ast.File] as the
+// file's complete extent.
+//
+// Precondition: n must not be nil.
+func NodeContains(n ast.Node, rng Range) bool {
+	return NodeRange(n).Contains(rng)
+}
+
+// NodeContainsPos reports whether the Pos/End range of node n encloses
+// the given pos.
+//
+// Like [NodeRange], it treats the range of an [ast.File] as the
+// file's complete extent.
+func NodeContainsPos(n ast.Node, pos token.Pos) bool {
+	return NodeRange(n).ContainsPos(pos)
+}
+
+// EnclosingFile returns the syntax tree for the file enclosing c.
+//
+// TODO(adonovan): promote this to a method of Cursor.
+func EnclosingFile(c inspector.Cursor) *ast.File {
+	c, _ = moreiters.First(c.Enclosing((*ast.File)(nil)))
+	return c.Node().(*ast.File)
+}
+
+// DocComment returns the doc comment for a node, if any.
+func DocComment(n ast.Node) *ast.CommentGroup {
+	switch n := n.(type) {
+	case *ast.FuncDecl:
+		return n.Doc
+	case *ast.GenDecl:
+		return n.Doc
+	case *ast.ValueSpec:
+		return n.Doc
+	case *ast.TypeSpec:
+		return n.Doc
+	case *ast.File:
+		return n.Doc
+	case *ast.ImportSpec:
+		return n.Doc
+	case *ast.Field:
+		return n.Doc
+	}
+	return nil
+}
+
+// Format returns a string representation of the node n.
+func Format(fset *token.FileSet, n ast.Node) string {
+	var buf strings.Builder
+	printer.Fprint(&buf, fset, n) // ignore errors
+	return buf.String()
+}
+
+// -- Range --
+
+// Range is a Pos interval.
+// It implements [analysis.Range] and [ast.Node].
+type Range struct{ Start, EndPos token.Pos }
+
+// RangeOf constructs a Range.
+//
+// RangeOf exists to pacify the "unkeyed literal" (composites) vet
+// check. It would be nice if there were a way for a type to add
+// itself to the allowlist.
+func RangeOf(start, end token.Pos) Range { return Range{start, end} }
+
+// NodeRange returns the extent of node n as a Range.
+//
+// For unfortunate historical reasons, the Pos/End extent of an
+// ast.File runs from the start of its package declaration---excluding
+// copyright comments, build tags, and package documentation---to the
+// end of its last declaration, excluding any trailing comments. So,
+// as a special case, if n is an [ast.File], NodeContains uses
+// n.FileStart <= pos && pos <= n.FileEnd to report whether the
+// position lies anywhere within the file.
+func NodeRange(n ast.Node) Range {
+	if file, ok := n.(*ast.File); ok {
+		return Range{file.FileStart, file.FileEnd} // entire file
+	}
+	return Range{n.Pos(), n.End()}
+}
+
+func (r Range) Pos() token.Pos { return r.Start }
+func (r Range) End() token.Pos { return r.EndPos }
+
+// ContainsPos reports whether the range (inclusive of both end points)
+// includes the specified position.
+func (r Range) ContainsPos(pos token.Pos) bool {
+	return r.Contains(RangeOf(pos, pos))
+}
+
+// Contains reports whether the range (inclusive of both end points)
+// includes the specified range.
+func (r Range) Contains(rng Range) bool {
+	return r.Start <= rng.Start && rng.EndPos <= r.EndPos
+}
+
+// IsValid reports whether the range is valid.
+func (r Range) IsValid() bool { return r.Start.IsValid() && r.Start <= r.EndPos }
+
+// --
+
+// Select returns the syntax nodes identified by a user's text
+// selection. It returns three nodes: the innermost node that wholly
+// encloses the selection; and the first and last nodes that are
+// wholly enclosed by the selection.
+//
+// For example, given this selection:
+//
+//	{ f(); g(); /* comment */ }
+//	  ~~~~~~~~~~~
+//
+// Select returns the enclosing BlockStmt, the f() CallExpr, and the g() CallExpr.
+//
+// If the selection does not wholly enclose any nodes, Select returns an error
+// and invalid start/end nodes, but it may return a valid enclosing node.
+//
+// Callers that require exactly one syntax tree (e.g. just f() or just
+// g()) should check that the returned start and end nodes are
+// identical.
+//
+// This function is intended to be called early in the handling of a
+// user's request, since it is tolerant of sloppy selection including
+// extraneous whitespace and comments. Use it in new code instead of
+// PathEnclosingInterval. When the exact extent of a node is known,
+// use [Cursor.FindByPos] instead.
+//
+// TODO(hxjiang): Consider refactoring the function signature. It is currently
+// confusing that an error is returned even when a valid enclosing node is
+// successfully found. Consider grouping all cursors into one struct.
+func Select(curFile inspector.Cursor, start, end token.Pos) (_enclosing, _start, _end inspector.Cursor, _ error) {
+	curEnclosing, ok := curFile.FindByPos(start, end)
+	if !ok {
+		return noCursor, noCursor, noCursor, fmt.Errorf("invalid selection")
+	}
+
+	// Find the first and last node wholly within the (start, end) range.
+	// We'll narrow the effective selection to them, to exclude whitespace.
+	// (This matches the functionality of PathEnclosingInterval.)
+	var curStart, curEnd inspector.Cursor
+	rng := RangeOf(start, end)
+	for cur := range curEnclosing.Preorder() {
+		if rng.Contains(NodeRange(cur.Node())) {
+			// The start node has the least Pos.
+			if !curStart.Valid() {
+				curStart = cur
+			}
+			// The end node has the greatest End.
+			// End positions do not change monotonically,
+			// so we must compute the max.
+			if !curEnd.Valid() ||
+				cur.Node().End() > curEnd.Node().End() {
+				curEnd = cur
+			}
+		}
+	}
+	if !curStart.Valid() {
+		// The selection is valid (inside curEnclosing) but contains no
+		// complete nodes. This happens for point selections (start == end),
+		// or selections covering only only spaces, comments, and punctuation
+		// tokens.
+		// Return the enclosing node so the caller can still use the context.
+		return curEnclosing, noCursor, noCursor, fmt.Errorf("invalid selection")
+	}
+	return curEnclosing, curStart, curEnd, nil
+}
+
+var noCursor inspector.Cursor
+
+// MaybeParenthesize returns new, possibly wrapped in parens if needed
+// to preserve operator precedence when it replaces old, whose parent
+// is parentNode.
+//
+// (This would be more naturally written in terms of Cursor, but one of
+// the callers--the inliner--does not have cursors handy.)
+func MaybeParenthesize(parentNode ast.Node, old, new ast.Expr) ast.Expr {
+	if needsParens(parentNode, old, new) {
+		new = &ast.ParenExpr{X: new}
+	}
+	return new
+}
+
+func needsParens(parentNode ast.Node, old, new ast.Expr) bool {
+	// An expression beneath a non-expression
+	// has no precedence ambiguity.
+	parent, ok := parentNode.(ast.Expr)
+	if !ok {
+		return false
+	}
+
+	precedence := func(n ast.Node) int {
+		switch n := n.(type) {
+		case *ast.UnaryExpr, *ast.StarExpr:
+			return token.UnaryPrec
+		case *ast.BinaryExpr:
+			return n.Op.Precedence()
+		}
+		return -1
+	}
+
+	// Parens are not required if the new node
+	// is not unary or binary.
+	newprec := precedence(new)
+	if newprec < 0 {
+		return false
+	}
+
+	// Parens are required if parent and child are both
+	// unary or binary and the parent has higher precedence.
+	if precedence(parent) > newprec {
+		return true
+	}
+
+	// Was the old node the operand of a postfix operator?
+	//  f().sel
+	//  f()[i:j]
+	//  f()[i]
+	//  f().(T)
+	//  f()(x)
+	switch parent := parent.(type) {
+	case *ast.SelectorExpr:
+		return parent.X == old
+	case *ast.IndexExpr:
+		return parent.X == old
+	case *ast.SliceExpr:
+		return parent.X == old
+	case *ast.TypeAssertExpr:
+		return parent.X == old
+	case *ast.CallExpr:
+		return parent.Fun == old
+	}
+	return false
+}
+
+func is[T any](n any) bool {
+	_, ok := n.(T)
+	return ok
+}