vendor: golang.org/x/text v0.31.0

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2025-11-27 19:12:17 +01:00
parent 3f5c571f69
commit ae3eed7b80
48 changed files with 2658 additions and 313 deletions
@@ -70,6 +70,10 @@
 //	PillAspirin // Aspirin
 //
 // to suppress it in the output.
+//
+// The -trimprefix flag specifies a prefix to remove from the constant names
+// when generating the string representations. For instance, -trimprefix=Pill
+// would be an alternative way to ensure that PillAspirin.String() == "Aspirin".
 package main // import "golang.org/x/tools/cmd/stringer"

 import (
@@ -209,7 +213,7 @@ func main() {
 			// and the separate package of tests (package foo_test).
 			outputName = filepath.Join(dir, baseName(pkg, foundTypes[0]))
 		}
-		err := os.WriteFile(outputName, src, 0644)
+		err := os.WriteFile(outputName, src, 0o644)
 		if err != nil {
 			log.Fatalf("writing output: %s", err)
 		}
@@ -637,44 +641,19 @@ func (g *Generator) buildOneRun(runs [][]Value, typeName string) {
 	values := runs[0]
 	g.Printf("\n")
 	g.declareIndexAndNameVar(values, typeName)
-	// The generated code is simple enough to write as a Printf format.
-	lessThanZero := ""
-	if values[0].signed {
-		lessThanZero = "i < 0 || "
-	}
-	if values[0].value == 0 { // Signed or unsigned, 0 is still 0.
-		g.Printf(stringOneRun, typeName, usize(len(values)), lessThanZero)
-	} else {
-		g.Printf(stringOneRunWithOffset, typeName, values[0].String(), usize(len(values)), lessThanZero)
-	}
+	g.Printf(stringOneRun, typeName, values[0].String())
 }

 // Arguments to format are:
 //
 //	[1]: type name
-//	[2]: size of index element (8 for uint8 etc.)
-//	[3]: less than zero check (for signed types)
+//	[2]: lowest defined value for type, as a string
 const stringOneRun = `func (i %[1]s) String() string {
-	if %[3]si >= %[1]s(len(_%[1]s_index)-1) {
+	idx := int(i) - %[2]s
+	if i < %[2]s || idx >= len(_%[1]s_index)-1 {
 		return "%[1]s(" + strconv.FormatInt(int64(i), 10) + ")"
 	}
-	return _%[1]s_name[_%[1]s_index[i]:_%[1]s_index[i+1]]
-}
-`
-
-// Arguments to format are:
-//	[1]: type name
-//	[2]: lowest defined value for type, as a string
-//	[3]: size of index element (8 for uint8 etc.)
-//	[4]: less than zero check (for signed types)
-/*
- */
-const stringOneRunWithOffset = `func (i %[1]s) String() string {
-	i -= %[2]s
-	if %[4]si >= %[1]s(len(_%[1]s_index)-1) {
-		return "%[1]s(" + strconv.FormatInt(int64(i + %[2]s), 10) + ")"
-	}
-	return _%[1]s_name[_%[1]s_index[i] : _%[1]s_index[i+1]]
+	return _%[1]s_name[_%[1]s_index[idx] : _%[1]s_index[idx+1]]
 }
 `

@@ -0,0 +1,295 @@
+// 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 edge defines identifiers for each field of an ast.Node
+// struct type that refers to another Node.
+package edge
+
+import (
+	"fmt"
+	"go/ast"
+	"reflect"
+)
+
+// A Kind describes a field of an ast.Node struct.
+type Kind uint8
+
+// String returns a description of the edge kind.
+func (k Kind) String() string {
+	if k == Invalid {
+		return "<invalid>"
+	}
+	info := fieldInfos[k]
+	return fmt.Sprintf("%v.%s", info.nodeType.Elem().Name(), info.name)
+}
+
+// NodeType returns the pointer-to-struct type of the ast.Node implementation.
+func (k Kind) NodeType() reflect.Type { return fieldInfos[k].nodeType }
+
+// FieldName returns the name of the field.
+func (k Kind) FieldName() string { return fieldInfos[k].name }
+
+// FieldType returns the declared type of the field.
+func (k Kind) FieldType() reflect.Type { return fieldInfos[k].fieldType }
+
+// Get returns the direct child of n identified by (k, idx).
+// n's type must match k.NodeType().
+// idx must be a valid slice index, or -1 for a non-slice.
+func (k Kind) Get(n ast.Node, idx int) ast.Node {
+	if k.NodeType() != reflect.TypeOf(n) {
+		panic(fmt.Sprintf("%v.Get(%T): invalid node type", k, n))
+	}
+	v := reflect.ValueOf(n).Elem().Field(fieldInfos[k].index)
+	if idx != -1 {
+		v = v.Index(idx) // asserts valid index
+	} else {
+		// (The type assertion below asserts that v is not a slice.)
+	}
+	return v.Interface().(ast.Node) // may be nil
+}
+
+const (
+	Invalid Kind = iota // for nodes at the root of the traversal
+
+	// Kinds are sorted alphabetically.
+	// Numbering is not stable.
+	// Each is named Type_Field, where Type is the
+	// ast.Node struct type and Field is the name of the field
+
+	ArrayType_Elt
+	ArrayType_Len
+	AssignStmt_Lhs
+	AssignStmt_Rhs
+	BinaryExpr_X
+	BinaryExpr_Y
+	BlockStmt_List
+	BranchStmt_Label
+	CallExpr_Args
+	CallExpr_Fun
+	CaseClause_Body
+	CaseClause_List
+	ChanType_Value
+	CommClause_Body
+	CommClause_Comm
+	CommentGroup_List
+	CompositeLit_Elts
+	CompositeLit_Type
+	DeclStmt_Decl
+	DeferStmt_Call
+	Ellipsis_Elt
+	ExprStmt_X
+	FieldList_List
+	Field_Comment
+	Field_Doc
+	Field_Names
+	Field_Tag
+	Field_Type
+	File_Decls
+	File_Doc
+	File_Name
+	ForStmt_Body
+	ForStmt_Cond
+	ForStmt_Init
+	ForStmt_Post
+	FuncDecl_Body
+	FuncDecl_Doc
+	FuncDecl_Name
+	FuncDecl_Recv
+	FuncDecl_Type
+	FuncLit_Body
+	FuncLit_Type
+	FuncType_Params
+	FuncType_Results
+	FuncType_TypeParams
+	GenDecl_Doc
+	GenDecl_Specs
+	GoStmt_Call
+	IfStmt_Body
+	IfStmt_Cond
+	IfStmt_Else
+	IfStmt_Init
+	ImportSpec_Comment
+	ImportSpec_Doc
+	ImportSpec_Name
+	ImportSpec_Path
+	IncDecStmt_X
+	IndexExpr_Index
+	IndexExpr_X
+	IndexListExpr_Indices
+	IndexListExpr_X
+	InterfaceType_Methods
+	KeyValueExpr_Key
+	KeyValueExpr_Value
+	LabeledStmt_Label
+	LabeledStmt_Stmt
+	MapType_Key
+	MapType_Value
+	ParenExpr_X
+	RangeStmt_Body
+	RangeStmt_Key
+	RangeStmt_Value
+	RangeStmt_X
+	ReturnStmt_Results
+	SelectStmt_Body
+	SelectorExpr_Sel
+	SelectorExpr_X
+	SendStmt_Chan
+	SendStmt_Value
+	SliceExpr_High
+	SliceExpr_Low
+	SliceExpr_Max
+	SliceExpr_X
+	StarExpr_X
+	StructType_Fields
+	SwitchStmt_Body
+	SwitchStmt_Init
+	SwitchStmt_Tag
+	TypeAssertExpr_Type
+	TypeAssertExpr_X
+	TypeSpec_Comment
+	TypeSpec_Doc
+	TypeSpec_Name
+	TypeSpec_Type
+	TypeSpec_TypeParams
+	TypeSwitchStmt_Assign
+	TypeSwitchStmt_Body
+	TypeSwitchStmt_Init
+	UnaryExpr_X
+	ValueSpec_Comment
+	ValueSpec_Doc
+	ValueSpec_Names
+	ValueSpec_Type
+	ValueSpec_Values
+
+	maxKind
+)
+
+// Assert that the encoding fits in 7 bits,
+// as the inspector relies on this.
+// (We are currently at 104.)
+var _ = [1 << 7]struct{}{}[maxKind]
+
+type fieldInfo struct {
+	nodeType  reflect.Type // pointer-to-struct type of ast.Node implementation
+	name      string
+	index     int
+	fieldType reflect.Type
+}
+
+func info[N ast.Node](fieldName string) fieldInfo {
+	nodePtrType := reflect.TypeFor[N]()
+	f, ok := nodePtrType.Elem().FieldByName(fieldName)
+	if !ok {
+		panic(fieldName)
+	}
+	return fieldInfo{nodePtrType, fieldName, f.Index[0], f.Type}
+}
+
+var fieldInfos = [...]fieldInfo{
+	Invalid:               {},
+	ArrayType_Elt:         info[*ast.ArrayType]("Elt"),
+	ArrayType_Len:         info[*ast.ArrayType]("Len"),
+	AssignStmt_Lhs:        info[*ast.AssignStmt]("Lhs"),
+	AssignStmt_Rhs:        info[*ast.AssignStmt]("Rhs"),
+	BinaryExpr_X:          info[*ast.BinaryExpr]("X"),
+	BinaryExpr_Y:          info[*ast.BinaryExpr]("Y"),
+	BlockStmt_List:        info[*ast.BlockStmt]("List"),
+	BranchStmt_Label:      info[*ast.BranchStmt]("Label"),
+	CallExpr_Args:         info[*ast.CallExpr]("Args"),
+	CallExpr_Fun:          info[*ast.CallExpr]("Fun"),
+	CaseClause_Body:       info[*ast.CaseClause]("Body"),
+	CaseClause_List:       info[*ast.CaseClause]("List"),
+	ChanType_Value:        info[*ast.ChanType]("Value"),
+	CommClause_Body:       info[*ast.CommClause]("Body"),
+	CommClause_Comm:       info[*ast.CommClause]("Comm"),
+	CommentGroup_List:     info[*ast.CommentGroup]("List"),
+	CompositeLit_Elts:     info[*ast.CompositeLit]("Elts"),
+	CompositeLit_Type:     info[*ast.CompositeLit]("Type"),
+	DeclStmt_Decl:         info[*ast.DeclStmt]("Decl"),
+	DeferStmt_Call:        info[*ast.DeferStmt]("Call"),
+	Ellipsis_Elt:          info[*ast.Ellipsis]("Elt"),
+	ExprStmt_X:            info[*ast.ExprStmt]("X"),
+	FieldList_List:        info[*ast.FieldList]("List"),
+	Field_Comment:         info[*ast.Field]("Comment"),
+	Field_Doc:             info[*ast.Field]("Doc"),
+	Field_Names:           info[*ast.Field]("Names"),
+	Field_Tag:             info[*ast.Field]("Tag"),
+	Field_Type:            info[*ast.Field]("Type"),
+	File_Decls:            info[*ast.File]("Decls"),
+	File_Doc:              info[*ast.File]("Doc"),
+	File_Name:             info[*ast.File]("Name"),
+	ForStmt_Body:          info[*ast.ForStmt]("Body"),
+	ForStmt_Cond:          info[*ast.ForStmt]("Cond"),
+	ForStmt_Init:          info[*ast.ForStmt]("Init"),
+	ForStmt_Post:          info[*ast.ForStmt]("Post"),
+	FuncDecl_Body:         info[*ast.FuncDecl]("Body"),
+	FuncDecl_Doc:          info[*ast.FuncDecl]("Doc"),
+	FuncDecl_Name:         info[*ast.FuncDecl]("Name"),
+	FuncDecl_Recv:         info[*ast.FuncDecl]("Recv"),
+	FuncDecl_Type:         info[*ast.FuncDecl]("Type"),
+	FuncLit_Body:          info[*ast.FuncLit]("Body"),
+	FuncLit_Type:          info[*ast.FuncLit]("Type"),
+	FuncType_Params:       info[*ast.FuncType]("Params"),
+	FuncType_Results:      info[*ast.FuncType]("Results"),
+	FuncType_TypeParams:   info[*ast.FuncType]("TypeParams"),
+	GenDecl_Doc:           info[*ast.GenDecl]("Doc"),
+	GenDecl_Specs:         info[*ast.GenDecl]("Specs"),
+	GoStmt_Call:           info[*ast.GoStmt]("Call"),
+	IfStmt_Body:           info[*ast.IfStmt]("Body"),
+	IfStmt_Cond:           info[*ast.IfStmt]("Cond"),
+	IfStmt_Else:           info[*ast.IfStmt]("Else"),
+	IfStmt_Init:           info[*ast.IfStmt]("Init"),
+	ImportSpec_Comment:    info[*ast.ImportSpec]("Comment"),
+	ImportSpec_Doc:        info[*ast.ImportSpec]("Doc"),
+	ImportSpec_Name:       info[*ast.ImportSpec]("Name"),
+	ImportSpec_Path:       info[*ast.ImportSpec]("Path"),
+	IncDecStmt_X:          info[*ast.IncDecStmt]("X"),
+	IndexExpr_Index:       info[*ast.IndexExpr]("Index"),
+	IndexExpr_X:           info[*ast.IndexExpr]("X"),
+	IndexListExpr_Indices: info[*ast.IndexListExpr]("Indices"),
+	IndexListExpr_X:       info[*ast.IndexListExpr]("X"),
+	InterfaceType_Methods: info[*ast.InterfaceType]("Methods"),
+	KeyValueExpr_Key:      info[*ast.KeyValueExpr]("Key"),
+	KeyValueExpr_Value:    info[*ast.KeyValueExpr]("Value"),
+	LabeledStmt_Label:     info[*ast.LabeledStmt]("Label"),
+	LabeledStmt_Stmt:      info[*ast.LabeledStmt]("Stmt"),
+	MapType_Key:           info[*ast.MapType]("Key"),
+	MapType_Value:         info[*ast.MapType]("Value"),
+	ParenExpr_X:           info[*ast.ParenExpr]("X"),
+	RangeStmt_Body:        info[*ast.RangeStmt]("Body"),
+	RangeStmt_Key:         info[*ast.RangeStmt]("Key"),
+	RangeStmt_Value:       info[*ast.RangeStmt]("Value"),
+	RangeStmt_X:           info[*ast.RangeStmt]("X"),
+	ReturnStmt_Results:    info[*ast.ReturnStmt]("Results"),
+	SelectStmt_Body:       info[*ast.SelectStmt]("Body"),
+	SelectorExpr_Sel:      info[*ast.SelectorExpr]("Sel"),
+	SelectorExpr_X:        info[*ast.SelectorExpr]("X"),
+	SendStmt_Chan:         info[*ast.SendStmt]("Chan"),
+	SendStmt_Value:        info[*ast.SendStmt]("Value"),
+	SliceExpr_High:        info[*ast.SliceExpr]("High"),
+	SliceExpr_Low:         info[*ast.SliceExpr]("Low"),
+	SliceExpr_Max:         info[*ast.SliceExpr]("Max"),
+	SliceExpr_X:           info[*ast.SliceExpr]("X"),
+	StarExpr_X:            info[*ast.StarExpr]("X"),
+	StructType_Fields:     info[*ast.StructType]("Fields"),
+	SwitchStmt_Body:       info[*ast.SwitchStmt]("Body"),
+	SwitchStmt_Init:       info[*ast.SwitchStmt]("Init"),
+	SwitchStmt_Tag:        info[*ast.SwitchStmt]("Tag"),
+	TypeAssertExpr_Type:   info[*ast.TypeAssertExpr]("Type"),
+	TypeAssertExpr_X:      info[*ast.TypeAssertExpr]("X"),
+	TypeSpec_Comment:      info[*ast.TypeSpec]("Comment"),
+	TypeSpec_Doc:          info[*ast.TypeSpec]("Doc"),
+	TypeSpec_Name:         info[*ast.TypeSpec]("Name"),
+	TypeSpec_Type:         info[*ast.TypeSpec]("Type"),
+	TypeSpec_TypeParams:   info[*ast.TypeSpec]("TypeParams"),
+	TypeSwitchStmt_Assign: info[*ast.TypeSwitchStmt]("Assign"),
+	TypeSwitchStmt_Body:   info[*ast.TypeSwitchStmt]("Body"),
+	TypeSwitchStmt_Init:   info[*ast.TypeSwitchStmt]("Init"),
+	UnaryExpr_X:           info[*ast.UnaryExpr]("X"),
+	ValueSpec_Comment:     info[*ast.ValueSpec]("Comment"),
+	ValueSpec_Doc:         info[*ast.ValueSpec]("Doc"),
+	ValueSpec_Names:       info[*ast.ValueSpec]("Names"),
+	ValueSpec_Type:        info[*ast.ValueSpec]("Type"),
+	ValueSpec_Values:      info[*ast.ValueSpec]("Values"),
+}
@@ -0,0 +1,502 @@
+// 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 inspector
+
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+	"iter"
+	"reflect"
+
+	"golang.org/x/tools/go/ast/edge"
+)
+
+// A Cursor represents an [ast.Node]. It is immutable.
+//
+// Two Cursors compare equal if they represent the same node.
+//
+// Call [Inspector.Root] to obtain a valid cursor for the virtual root
+// node of the traversal.
+//
+// Use the following methods to navigate efficiently around the tree:
+//   - for ancestors, use [Cursor.Parent] and [Cursor.Enclosing];
+//   - for children, use [Cursor.Child], [Cursor.Children],
+//     [Cursor.FirstChild], and [Cursor.LastChild];
+//   - for siblings, use [Cursor.PrevSibling] and [Cursor.NextSibling];
+//   - for descendants, use [Cursor.FindByPos], [Cursor.FindNode],
+//     [Cursor.Inspect], and [Cursor.Preorder].
+//
+// Use the [Cursor.ChildAt] and [Cursor.ParentEdge] methods for
+// information about the edges in a tree: which field (and slice
+// element) of the parent node holds the child.
+type Cursor struct {
+	in    *Inspector
+	index int32 // index of push node; -1 for virtual root node
+}
+
+// Root returns a cursor for the virtual root node,
+// whose children are the files provided to [New].
+//
+// Its [Cursor.Node] method return nil.
+func (in *Inspector) Root() Cursor {
+	return Cursor{in, -1}
+}
+
+// At returns the cursor at the specified index in the traversal,
+// which must have been obtained from [Cursor.Index] on a Cursor
+// belonging to the same Inspector (see [Cursor.Inspector]).
+func (in *Inspector) At(index int32) Cursor {
+	if index < 0 {
+		panic("negative index")
+	}
+	if int(index) >= len(in.events) {
+		panic("index out of range for this inspector")
+	}
+	if in.events[index].index < index {
+		panic("invalid index") // (a push, not a pop)
+	}
+	return Cursor{in, index}
+}
+
+// Inspector returns the cursor's Inspector.
+func (c Cursor) Inspector() *Inspector { return c.in }
+
+// Index returns the index of this cursor position within the package.
+//
+// Clients should not assume anything about the numeric Index value
+// except that it increases monotonically throughout the traversal.
+// It is provided for use with [At].
+//
+// Index must not be called on the Root node.
+func (c Cursor) Index() int32 {
+	if c.index < 0 {
+		panic("Index called on Root node")
+	}
+	return c.index
+}
+
+// Node returns the node at the current cursor position,
+// or nil for the cursor returned by [Inspector.Root].
+func (c Cursor) Node() ast.Node {
+	if c.index < 0 {
+		return nil
+	}
+	return c.in.events[c.index].node
+}
+
+// String returns information about the cursor's node, if any.
+func (c Cursor) String() string {
+	if c.in == nil {
+		return "(invalid)"
+	}
+	if c.index < 0 {
+		return "(root)"
+	}
+	return reflect.TypeOf(c.Node()).String()
+}
+
+// indices return the [start, end) half-open interval of event indices.
+func (c Cursor) indices() (int32, int32) {
+	if c.index < 0 {
+		return 0, int32(len(c.in.events)) // root: all events
+	} else {
+		return c.index, c.in.events[c.index].index + 1 // just one subtree
+	}
+}
+
+// Preorder returns an iterator over the nodes of the subtree
+// represented by c in depth-first order. Each node in the sequence is
+// represented by a Cursor that allows access to the Node, but may
+// also be used to start a new traversal, or to obtain the stack of
+// nodes enclosing the cursor.
+//
+// The traversal sequence is determined by [ast.Inspect]. The types
+// argument, if non-empty, enables type-based filtering of events. The
+// function f if is called only for nodes whose type matches an
+// element of the types slice.
+//
+// If you need control over descent into subtrees,
+// or need both pre- and post-order notifications, use [Cursor.Inspect]
+func (c Cursor) Preorder(types ...ast.Node) iter.Seq[Cursor] {
+	mask := maskOf(types)
+
+	return func(yield func(Cursor) bool) {
+		events := c.in.events
+
+		for i, limit := c.indices(); i < limit; {
+			ev := events[i]
+			if ev.index > i { // push?
+				if ev.typ&mask != 0 && !yield(Cursor{c.in, i}) {
+					break
+				}
+				pop := ev.index
+				if events[pop].typ&mask == 0 {
+					// Subtree does not contain types: skip.
+					i = pop + 1
+					continue
+				}
+			}
+			i++
+		}
+	}
+}
+
+// Inspect visits the nodes of the subtree represented by c in
+// depth-first order. It calls f(n) for each node n before it
+// visits n's children. If f returns true, Inspect invokes f
+// recursively for each of the non-nil children of the node.
+//
+// Each node is represented by a Cursor that allows access to the
+// Node, but may also be used to start a new traversal, or to obtain
+// the stack of nodes enclosing the cursor.
+//
+// The complete traversal sequence is determined by [ast.Inspect].
+// The types argument, if non-empty, enables type-based filtering of
+// events. The function f if is called only for nodes whose type
+// matches an element of the types slice.
+func (c Cursor) Inspect(types []ast.Node, f func(c Cursor) (descend bool)) {
+	mask := maskOf(types)
+	events := c.in.events
+	for i, limit := c.indices(); i < limit; {
+		ev := events[i]
+		if ev.index > i {
+			// push
+			pop := ev.index
+			if ev.typ&mask != 0 && !f(Cursor{c.in, i}) ||
+				events[pop].typ&mask == 0 {
+				// The user opted not to descend, or the
+				// subtree does not contain types:
+				// skip past the pop.
+				i = pop + 1
+				continue
+			}
+		}
+		i++
+	}
+}
+
+// Enclosing returns an iterator over the nodes enclosing the current
+// current node, starting with the Cursor itself.
+//
+// Enclosing must not be called on the Root node (whose [Cursor.Node] returns nil).
+//
+// The types argument, if non-empty, enables type-based filtering of
+// events: the sequence includes only enclosing nodes whose type
+// matches an element of the types slice.
+func (c Cursor) Enclosing(types ...ast.Node) iter.Seq[Cursor] {
+	if c.index < 0 {
+		panic("Cursor.Enclosing called on Root node")
+	}
+
+	mask := maskOf(types)
+
+	return func(yield func(Cursor) bool) {
+		events := c.in.events
+		for i := c.index; i >= 0; i = events[i].parent {
+			if events[i].typ&mask != 0 && !yield(Cursor{c.in, i}) {
+				break
+			}
+		}
+	}
+}
+
+// Parent returns the parent of the current node.
+//
+// Parent must not be called on the Root node (whose [Cursor.Node] returns nil).
+func (c Cursor) Parent() Cursor {
+	if c.index < 0 {
+		panic("Cursor.Parent called on Root node")
+	}
+
+	return Cursor{c.in, c.in.events[c.index].parent}
+}
+
+// ParentEdge returns the identity of the field in the parent node
+// that holds this cursor's node, and if it is a list, the index within it.
+//
+// For example, f(x, y) is a CallExpr whose three children are Idents.
+// f has edge kind [edge.CallExpr_Fun] and index -1.
+// x and y have kind [edge.CallExpr_Args] and indices 0 and 1, respectively.
+//
+// If called on a child of the Root node, it returns ([edge.Invalid], -1).
+//
+// ParentEdge must not be called on the Root node (whose [Cursor.Node] returns nil).
+func (c Cursor) ParentEdge() (edge.Kind, int) {
+	if c.index < 0 {
+		panic("Cursor.ParentEdge called on Root node")
+	}
+	events := c.in.events
+	pop := events[c.index].index
+	return unpackEdgeKindAndIndex(events[pop].parent)
+}
+
+// ChildAt returns the cursor for the child of the
+// current node identified by its edge and index.
+// The index must be -1 if the edge.Kind is not a slice.
+// The indicated child node must exist.
+//
+// ChildAt must not be called on the Root node (whose [Cursor.Node] returns nil).
+//
+// Invariant: c.Parent().ChildAt(c.ParentEdge()) == c.
+func (c Cursor) ChildAt(k edge.Kind, idx int) Cursor {
+	target := packEdgeKindAndIndex(k, idx)
+
+	// Unfortunately there's no shortcut to looping.
+	events := c.in.events
+	i := c.index + 1
+	for {
+		pop := events[i].index
+		if pop < i {
+			break
+		}
+		if events[pop].parent == target {
+			return Cursor{c.in, i}
+		}
+		i = pop + 1
+	}
+	panic(fmt.Sprintf("ChildAt(%v, %d): no such child of %v", k, idx, c))
+}
+
+// Child returns the cursor for n, which must be a direct child of c's Node.
+//
+// Child must not be called on the Root node (whose [Cursor.Node] returns nil).
+func (c Cursor) Child(n ast.Node) Cursor {
+	if c.index < 0 {
+		panic("Cursor.Child called on Root node")
+	}
+
+	if false {
+		// reference implementation
+		for child := range c.Children() {
+			if child.Node() == n {
+				return child
+			}
+		}
+
+	} else {
+		// optimized implementation
+		events := c.in.events
+		for i := c.index + 1; events[i].index > i; i = events[i].index + 1 {
+			if events[i].node == n {
+				return Cursor{c.in, i}
+			}
+		}
+	}
+	panic(fmt.Sprintf("Child(%T): not a child of %v", n, c))
+}
+
+// NextSibling returns the cursor for the next sibling node in the same list
+// (for example, of files, decls, specs, statements, fields, or expressions) as
+// the current node. It returns (zero, false) if the node is the last node in
+// the list, or is not part of a list.
+//
+// NextSibling must not be called on the Root node.
+//
+// See note at [Cursor.Children].
+func (c Cursor) NextSibling() (Cursor, bool) {
+	if c.index < 0 {
+		panic("Cursor.NextSibling called on Root node")
+	}
+
+	events := c.in.events
+	i := events[c.index].index + 1 // after corresponding pop
+	if i < int32(len(events)) {
+		if events[i].index > i { // push?
+			return Cursor{c.in, i}, true
+		}
+	}
+	return Cursor{}, false
+}
+
+// PrevSibling returns the cursor for the previous sibling node in the
+// same list (for example, of files, decls, specs, statements, fields,
+// or expressions) as the current node. It returns zero if the node is
+// the first node in the list, or is not part of a list.
+//
+// It must not be called on the Root node.
+//
+// See note at [Cursor.Children].
+func (c Cursor) PrevSibling() (Cursor, bool) {
+	if c.index < 0 {
+		panic("Cursor.PrevSibling called on Root node")
+	}
+
+	events := c.in.events
+	i := c.index - 1
+	if i >= 0 {
+		if j := events[i].index; j < i { // pop?
+			return Cursor{c.in, j}, true
+		}
+	}
+	return Cursor{}, false
+}
+
+// FirstChild returns the first direct child of the current node,
+// or zero if it has no children.
+func (c Cursor) FirstChild() (Cursor, bool) {
+	events := c.in.events
+	i := c.index + 1                                   // i=0 if c is root
+	if i < int32(len(events)) && events[i].index > i { // push?
+		return Cursor{c.in, i}, true
+	}
+	return Cursor{}, false
+}
+
+// LastChild returns the last direct child of the current node,
+// or zero if it has no children.
+func (c Cursor) LastChild() (Cursor, bool) {
+	events := c.in.events
+	if c.index < 0 { // root?
+		if len(events) > 0 {
+			// return push of final event (a pop)
+			return Cursor{c.in, events[len(events)-1].index}, true
+		}
+	} else {
+		j := events[c.index].index - 1 // before corresponding pop
+		// Inv: j == c.index if c has no children
+		//  or  j is last child's pop.
+		if j > c.index { // c has children
+			return Cursor{c.in, events[j].index}, true
+		}
+	}
+	return Cursor{}, false
+}
+
+// Children returns an iterator over the direct children of the
+// current node, if any.
+//
+// When using Children, NextChild, and PrevChild, bear in mind that a
+// Node's children may come from different fields, some of which may
+// be lists of nodes without a distinguished intervening container
+// such as [ast.BlockStmt].
+//
+// For example, [ast.CaseClause] has a field List of expressions and a
+// field Body of statements, so the children of a CaseClause are a mix
+// of expressions and statements. Other nodes that have "uncontained"
+// list fields include:
+//
+//   - [ast.ValueSpec] (Names, Values)
+//   - [ast.CompositeLit] (Type, Elts)
+//   - [ast.IndexListExpr] (X, Indices)
+//   - [ast.CallExpr] (Fun, Args)
+//   - [ast.AssignStmt] (Lhs, Rhs)
+//
+// So, do not assume that the previous sibling of an ast.Stmt is also
+// an ast.Stmt, or if it is, that they are executed sequentially,
+// unless you have established that, say, its parent is a BlockStmt
+// or its [Cursor.ParentEdge] is [edge.BlockStmt_List].
+// For example, given "for S1; ; S2 {}", the predecessor of S2 is S1,
+// even though they are not executed in sequence.
+func (c Cursor) Children() iter.Seq[Cursor] {
+	return func(yield func(Cursor) bool) {
+		c, ok := c.FirstChild()
+		for ok && yield(c) {
+			c, ok = c.NextSibling()
+		}
+	}
+}
+
+// Contains reports whether c contains or is equal to c2.
+//
+// Both Cursors must belong to the same [Inspector];
+// neither may be its Root node.
+func (c Cursor) Contains(c2 Cursor) bool {
+	if c.in != c2.in {
+		panic("different inspectors")
+	}
+	events := c.in.events
+	return c.index <= c2.index && events[c2.index].index <= events[c.index].index
+}
+
+// FindNode returns the cursor for node n if it belongs to the subtree
+// rooted at c. It returns zero if n is not found.
+func (c Cursor) FindNode(n ast.Node) (Cursor, bool) {
+
+	// FindNode is equivalent to this code,
+	// but more convenient and 15-20% faster:
+	if false {
+		for candidate := range c.Preorder(n) {
+			if candidate.Node() == n {
+				return candidate, true
+			}
+		}
+		return Cursor{}, false
+	}
+
+	// TODO(adonovan): opt: should we assume Node.Pos is accurate
+	// and combine type-based filtering with position filtering
+	// like FindByPos?
+
+	mask := maskOf([]ast.Node{n})
+	events := c.in.events
+
+	for i, limit := c.indices(); i < limit; i++ {
+		ev := events[i]
+		if ev.index > i { // push?
+			if ev.typ&mask != 0 && ev.node == n {
+				return Cursor{c.in, i}, true
+			}
+			pop := ev.index
+			if events[pop].typ&mask == 0 {
+				// Subtree does not contain type of n: skip.
+				i = pop
+			}
+		}
+	}
+	return Cursor{}, false
+}
+
+// FindByPos returns the cursor for the innermost node n in the tree
+// rooted at c such that n.Pos() <= start && end <= n.End().
+// (For an *ast.File, it uses the bounds n.FileStart-n.FileEnd.)
+//
+// It returns zero if none is found.
+// Precondition: start <= end.
+//
+// See also [astutil.PathEnclosingInterval], which
+// tolerates adjoining whitespace.
+func (c Cursor) FindByPos(start, end token.Pos) (Cursor, bool) {
+	if end < start {
+		panic("end < start")
+	}
+	events := c.in.events
+
+	// This algorithm could be implemented using c.Inspect,
+	// but it is about 2.5x slower.
+
+	best := int32(-1) // push index of latest (=innermost) node containing range
+	for i, limit := c.indices(); i < limit; i++ {
+		ev := events[i]
+		if ev.index > i { // push?
+			n := ev.node
+			var nodeEnd token.Pos
+			if file, ok := n.(*ast.File); ok {
+				nodeEnd = file.FileEnd
+				// Note: files may be out of Pos order.
+				if file.FileStart > start {
+					i = ev.index // disjoint, after; skip to next file
+					continue
+				}
+			} else {
+				nodeEnd = n.End()
+				if n.Pos() > start {
+					break // disjoint, after; stop
+				}
+			}
+			// Inv: node.{Pos,FileStart} <= start
+			if end <= nodeEnd {
+				// node fully contains target range
+				best = i
+			} else if nodeEnd < start {
+				i = ev.index // disjoint, before; skip forward
+			}
+		}
+	}
+	if best >= 0 {
+		return Cursor{c.in, best}, true
+	}
+	return Cursor{}, false
+}
@@ -0,0 +1,311 @@
+// Copyright 2018 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 inspector provides helper functions for traversal over the
+// syntax trees of a package, including node filtering by type, and
+// materialization of the traversal stack.
+//
+// During construction, the inspector does a complete traversal and
+// builds a list of push/pop events and their node type. Subsequent
+// method calls that request a traversal scan this list, rather than walk
+// the AST, and perform type filtering using efficient bit sets.
+// This representation is sometimes called a "balanced parenthesis tree."
+//
+// Experiments suggest the inspector's traversals are about 2.5x faster
+// than [ast.Inspect], but it may take around 5 traversals for this
+// benefit to amortize the inspector's construction cost.
+// If efficiency is the primary concern, do not use Inspector for
+// one-off traversals.
+//
+// The [Cursor] type provides a more flexible API for efficient
+// navigation of syntax trees in all four "cardinal directions". For
+// example, traversals may be nested, so you can find each node of
+// type A and then search within it for nodes of type B. Or you can
+// traverse from a node to its immediate neighbors: its parent, its
+// previous and next sibling, or its first and last child. We
+// recommend using methods of Cursor in preference to Inspector where
+// possible.
+package inspector
+
+// There are four orthogonal features in a traversal:
+//  1 type filtering
+//  2 pruning
+//  3 postorder calls to f
+//  4 stack
+// Rather than offer all of them in the API,
+// only a few combinations are exposed:
+// - Preorder is the fastest and has fewest features,
+//   but is the most commonly needed traversal.
+// - Nodes and WithStack both provide pruning and postorder calls,
+//   even though few clients need it, because supporting two versions
+//   is not justified.
+// More combinations could be supported by expressing them as
+// wrappers around a more generic traversal, but this was measured
+// and found to degrade performance significantly (30%).
+
+import (
+	"go/ast"
+
+	"golang.org/x/tools/go/ast/edge"
+)
+
+// An Inspector provides methods for inspecting
+// (traversing) the syntax trees of a package.
+type Inspector struct {
+	events []event
+}
+
+func packEdgeKindAndIndex(ek edge.Kind, index int) int32 {
+	return int32(uint32(index+1)<<7 | uint32(ek))
+}
+
+// unpackEdgeKindAndIndex unpacks the edge kind and edge index (within
+// an []ast.Node slice) from the parent field of a pop event.
+func unpackEdgeKindAndIndex(x int32) (edge.Kind, int) {
+	// The "parent" field of a pop node holds the
+	// edge Kind in the lower 7 bits and the index+1
+	// in the upper 25.
+	return edge.Kind(x & 0x7f), int(x>>7) - 1
+}
+
+// New returns an Inspector for the specified syntax trees.
+func New(files []*ast.File) *Inspector {
+	return &Inspector{traverse(files)}
+}
+
+// An event represents a push or a pop
+// of an ast.Node during a traversal.
+type event struct {
+	node   ast.Node
+	typ    uint64 // typeOf(node) on push event, or union of typ strictly between push and pop events on pop events
+	index  int32  // index of corresponding push or pop event
+	parent int32  // index of parent's push node (push nodes only), or packed edge kind/index (pop nodes only)
+}
+
+// TODO: Experiment with storing only the second word of event.node (unsafe.Pointer).
+// Type can be recovered from the sole bit in typ.
+// [Tried this, wasn't faster. --adonovan]
+
+// Preorder visits all the nodes of the files supplied to New in
+// depth-first order. It calls f(n) for each node n before it visits
+// n's children.
+//
+// The complete traversal sequence is determined by [ast.Inspect].
+// The types argument, if non-empty, enables type-based filtering of
+// events. The function f is called only for nodes whose type
+// matches an element of the types slice.
+//
+// The [Cursor.Preorder] method provides a richer alternative interface.
+// Example:
+//
+//	for c := range in.Root().Preorder(types) { ... }
+func (in *Inspector) Preorder(types []ast.Node, f func(ast.Node)) {
+	// Because it avoids postorder calls to f, and the pruning
+	// check, Preorder is almost twice as fast as Nodes. The two
+	// features seem to contribute similar slowdowns (~1.4x each).
+
+	// This function is equivalent to the PreorderSeq call below,
+	// but to avoid the additional dynamic call (which adds 13-35%
+	// to the benchmarks), we expand it out.
+	//
+	// in.PreorderSeq(types...)(func(n ast.Node) bool {
+	// 	f(n)
+	// 	return true
+	// })
+
+	mask := maskOf(types)
+	for i := int32(0); i < int32(len(in.events)); {
+		ev := in.events[i]
+		if ev.index > i {
+			// push
+			if ev.typ&mask != 0 {
+				f(ev.node)
+			}
+			pop := ev.index
+			if in.events[pop].typ&mask == 0 {
+				// Subtrees do not contain types: skip them and pop.
+				i = pop + 1
+				continue
+			}
+		}
+		i++
+	}
+}
+
+// Nodes visits the nodes of the files supplied to New in depth-first
+// order. It calls f(n, true) for each node n before it visits n's
+// children. If f returns true, Nodes invokes f recursively for each
+// of the non-nil children of the node, followed by a call of
+// f(n, false).
+//
+// The complete traversal sequence is determined by [ast.Inspect].
+// The types argument, if non-empty, enables type-based filtering of
+// events. The function f if is called only for nodes whose type
+// matches an element of the types slice.
+//
+// The [Cursor.Inspect] method provides a richer alternative interface.
+// Example:
+//
+//	in.Root().Inspect(types, func(c Cursor) bool {
+//		...
+//		return true
+//	}
+func (in *Inspector) Nodes(types []ast.Node, f func(n ast.Node, push bool) (proceed bool)) {
+	mask := maskOf(types)
+	for i := int32(0); i < int32(len(in.events)); {
+		ev := in.events[i]
+		if ev.index > i {
+			// push
+			pop := ev.index
+			if ev.typ&mask != 0 {
+				if !f(ev.node, true) {
+					i = pop + 1 // jump to corresponding pop + 1
+					continue
+				}
+			}
+			if in.events[pop].typ&mask == 0 {
+				// Subtrees do not contain types: skip them.
+				i = pop
+				continue
+			}
+		} else {
+			// pop
+			push := ev.index
+			if in.events[push].typ&mask != 0 {
+				f(ev.node, false)
+			}
+		}
+		i++
+	}
+}
+
+// WithStack visits nodes in a similar manner to Nodes, but it
+// supplies each call to f an additional argument, the current
+// traversal stack. The stack's first element is the outermost node,
+// an *ast.File; its last is the innermost, n.
+//
+// The [Cursor.Inspect] method provides a richer alternative interface.
+// Example:
+//
+//	in.Root().Inspect(types, func(c Cursor) bool {
+//		stack := slices.Collect(c.Enclosing())
+//		...
+//		return true
+//	})
+func (in *Inspector) WithStack(types []ast.Node, f func(n ast.Node, push bool, stack []ast.Node) (proceed bool)) {
+	mask := maskOf(types)
+	var stack []ast.Node
+	for i := int32(0); i < int32(len(in.events)); {
+		ev := in.events[i]
+		if ev.index > i {
+			// push
+			pop := ev.index
+			stack = append(stack, ev.node)
+			if ev.typ&mask != 0 {
+				if !f(ev.node, true, stack) {
+					i = pop + 1
+					stack = stack[:len(stack)-1]
+					continue
+				}
+			}
+			if in.events[pop].typ&mask == 0 {
+				// Subtrees does not contain types: skip them.
+				i = pop
+				continue
+			}
+		} else {
+			// pop
+			push := ev.index
+			if in.events[push].typ&mask != 0 {
+				f(ev.node, false, stack)
+			}
+			stack = stack[:len(stack)-1]
+		}
+		i++
+	}
+}
+
+// traverse builds the table of events representing a traversal.
+func traverse(files []*ast.File) []event {
+	// Preallocate approximate number of events
+	// based on source file extent of the declarations.
+	// (We use End-Pos not FileStart-FileEnd to neglect
+	// the effect of long doc comments.)
+	// This makes traverse faster by 4x (!).
+	var extent int
+	for _, f := range files {
+		extent += int(f.End() - f.Pos())
+	}
+	// This estimate is based on the net/http package.
+	capacity := min(extent*33/100, 1e6) // impose some reasonable maximum (1M)
+
+	v := &visitor{
+		events: make([]event, 0, capacity),
+		stack:  []item{{index: -1}}, // include an extra event so file nodes have a parent
+	}
+	for _, file := range files {
+		walk(v, edge.Invalid, -1, file)
+	}
+	return v.events
+}
+
+type visitor struct {
+	events []event
+	stack  []item
+}
+
+type item struct {
+	index            int32  // index of current node's push event
+	parentIndex      int32  // index of parent node's push event
+	typAccum         uint64 // accumulated type bits of current node's descendants
+	edgeKindAndIndex int32  // edge.Kind and index, bit packed
+}
+
+func (v *visitor) push(ek edge.Kind, eindex int, node ast.Node) {
+	var (
+		index       = int32(len(v.events))
+		parentIndex = v.stack[len(v.stack)-1].index
+	)
+	v.events = append(v.events, event{
+		node:   node,
+		parent: parentIndex,
+		typ:    typeOf(node),
+		index:  0, // (pop index is set later by visitor.pop)
+	})
+	v.stack = append(v.stack, item{
+		index:            index,
+		parentIndex:      parentIndex,
+		edgeKindAndIndex: packEdgeKindAndIndex(ek, eindex),
+	})
+
+	// 2B nodes ought to be enough for anyone!
+	if int32(len(v.events)) < 0 {
+		panic("event index exceeded int32")
+	}
+
+	// 32M elements in an []ast.Node ought to be enough for anyone!
+	if ek2, eindex2 := unpackEdgeKindAndIndex(packEdgeKindAndIndex(ek, eindex)); ek2 != ek || eindex2 != eindex {
+		panic("Node slice index exceeded uint25")
+	}
+}
+
+func (v *visitor) pop(node ast.Node) {
+	top := len(v.stack) - 1
+	current := v.stack[top]
+
+	push := &v.events[current.index]
+	parent := &v.stack[top-1]
+
+	push.index = int32(len(v.events))              // make push event refer to pop
+	parent.typAccum |= current.typAccum | push.typ // accumulate type bits into parent
+
+	v.stack = v.stack[:top]
+
+	v.events = append(v.events, event{
+		node:   node,
+		typ:    current.typAccum,
+		index:  current.index,
+		parent: current.edgeKindAndIndex, // see [unpackEdgeKindAndIndex]
+	})
+}
@@ -0,0 +1,85 @@
+// 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.
+
+//go:build go1.23
+
+package inspector
+
+import (
+	"go/ast"
+	"iter"
+)
+
+// PreorderSeq returns an iterator that visits all the
+// nodes of the files supplied to New in depth-first order.
+// It visits each node n before n's children.
+// The complete traversal sequence is determined by ast.Inspect.
+//
+// The types argument, if non-empty, enables type-based
+// filtering of events: only nodes whose type matches an
+// element of the types slice are included in the sequence.
+func (in *Inspector) PreorderSeq(types ...ast.Node) iter.Seq[ast.Node] {
+
+	// This implementation is identical to Preorder,
+	// except that it supports breaking out of the loop.
+
+	return func(yield func(ast.Node) bool) {
+		mask := maskOf(types)
+		for i := int32(0); i < int32(len(in.events)); {
+			ev := in.events[i]
+			if ev.index > i {
+				// push
+				if ev.typ&mask != 0 {
+					if !yield(ev.node) {
+						break
+					}
+				}
+				pop := ev.index
+				if in.events[pop].typ&mask == 0 {
+					// Subtrees do not contain types: skip them and pop.
+					i = pop + 1
+					continue
+				}
+			}
+			i++
+		}
+	}
+}
+
+// All[N] returns an iterator over all the nodes of type N.
+// N must be a pointer-to-struct type that implements ast.Node.
+//
+// Example:
+//
+//	for call := range All[*ast.CallExpr](in) { ... }
+func All[N interface {
+	*S
+	ast.Node
+}, S any](in *Inspector) iter.Seq[N] {
+
+	// To avoid additional dynamic call overheads,
+	// we duplicate rather than call the logic of PreorderSeq.
+
+	mask := typeOf((N)(nil))
+	return func(yield func(N) bool) {
+		for i := int32(0); i < int32(len(in.events)); {
+			ev := in.events[i]
+			if ev.index > i {
+				// push
+				if ev.typ&mask != 0 {
+					if !yield(ev.node.(N)) {
+						break
+					}
+				}
+				pop := ev.index
+				if in.events[pop].typ&mask == 0 {
+					// Subtrees do not contain types: skip them and pop.
+					i = pop + 1
+					continue
+				}
+			}
+			i++
+		}
+	}
+}
@@ -0,0 +1,227 @@
+// Copyright 2018 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 inspector
+
+// This file defines func typeOf(ast.Node) uint64.
+//
+// The initial map-based implementation was too slow;
+// see https://go-review.googlesource.com/c/tools/+/135655/1/go/ast/inspector/inspector.go#196
+
+import (
+	"go/ast"
+	"math"
+)
+
+const (
+	nArrayType = iota
+	nAssignStmt
+	nBadDecl
+	nBadExpr
+	nBadStmt
+	nBasicLit
+	nBinaryExpr
+	nBlockStmt
+	nBranchStmt
+	nCallExpr
+	nCaseClause
+	nChanType
+	nCommClause
+	nComment
+	nCommentGroup
+	nCompositeLit
+	nDeclStmt
+	nDeferStmt
+	nEllipsis
+	nEmptyStmt
+	nExprStmt
+	nField
+	nFieldList
+	nFile
+	nForStmt
+	nFuncDecl
+	nFuncLit
+	nFuncType
+	nGenDecl
+	nGoStmt
+	nIdent
+	nIfStmt
+	nImportSpec
+	nIncDecStmt
+	nIndexExpr
+	nIndexListExpr
+	nInterfaceType
+	nKeyValueExpr
+	nLabeledStmt
+	nMapType
+	nPackage
+	nParenExpr
+	nRangeStmt
+	nReturnStmt
+	nSelectStmt
+	nSelectorExpr
+	nSendStmt
+	nSliceExpr
+	nStarExpr
+	nStructType
+	nSwitchStmt
+	nTypeAssertExpr
+	nTypeSpec
+	nTypeSwitchStmt
+	nUnaryExpr
+	nValueSpec
+)
+
+// typeOf returns a distinct single-bit value that represents the type of n.
+//
+// Various implementations were benchmarked with BenchmarkNewInspector:
+//
+//	                                                                GOGC=off
+//	- type switch					4.9-5.5ms	2.1ms
+//	- binary search over a sorted list of types	5.5-5.9ms	2.5ms
+//	- linear scan, frequency-ordered list		5.9-6.1ms	2.7ms
+//	- linear scan, unordered list			6.4ms		2.7ms
+//	- hash table					6.5ms		3.1ms
+//
+// A perfect hash seemed like overkill.
+//
+// The compiler's switch statement is the clear winner
+// as it produces a binary tree in code,
+// with constant conditions and good branch prediction.
+// (Sadly it is the most verbose in source code.)
+// Binary search suffered from poor branch prediction.
+func typeOf(n ast.Node) uint64 {
+	// Fast path: nearly half of all nodes are identifiers.
+	if _, ok := n.(*ast.Ident); ok {
+		return 1 << nIdent
+	}
+
+	// These cases include all nodes encountered by ast.Inspect.
+	switch n.(type) {
+	case *ast.ArrayType:
+		return 1 << nArrayType
+	case *ast.AssignStmt:
+		return 1 << nAssignStmt
+	case *ast.BadDecl:
+		return 1 << nBadDecl
+	case *ast.BadExpr:
+		return 1 << nBadExpr
+	case *ast.BadStmt:
+		return 1 << nBadStmt
+	case *ast.BasicLit:
+		return 1 << nBasicLit
+	case *ast.BinaryExpr:
+		return 1 << nBinaryExpr
+	case *ast.BlockStmt:
+		return 1 << nBlockStmt
+	case *ast.BranchStmt:
+		return 1 << nBranchStmt
+	case *ast.CallExpr:
+		return 1 << nCallExpr
+	case *ast.CaseClause:
+		return 1 << nCaseClause
+	case *ast.ChanType:
+		return 1 << nChanType
+	case *ast.CommClause:
+		return 1 << nCommClause
+	case *ast.Comment:
+		return 1 << nComment
+	case *ast.CommentGroup:
+		return 1 << nCommentGroup
+	case *ast.CompositeLit:
+		return 1 << nCompositeLit
+	case *ast.DeclStmt:
+		return 1 << nDeclStmt
+	case *ast.DeferStmt:
+		return 1 << nDeferStmt
+	case *ast.Ellipsis:
+		return 1 << nEllipsis
+	case *ast.EmptyStmt:
+		return 1 << nEmptyStmt
+	case *ast.ExprStmt:
+		return 1 << nExprStmt
+	case *ast.Field:
+		return 1 << nField
+	case *ast.FieldList:
+		return 1 << nFieldList
+	case *ast.File:
+		return 1 << nFile
+	case *ast.ForStmt:
+		return 1 << nForStmt
+	case *ast.FuncDecl:
+		return 1 << nFuncDecl
+	case *ast.FuncLit:
+		return 1 << nFuncLit
+	case *ast.FuncType:
+		return 1 << nFuncType
+	case *ast.GenDecl:
+		return 1 << nGenDecl
+	case *ast.GoStmt:
+		return 1 << nGoStmt
+	case *ast.Ident:
+		return 1 << nIdent
+	case *ast.IfStmt:
+		return 1 << nIfStmt
+	case *ast.ImportSpec:
+		return 1 << nImportSpec
+	case *ast.IncDecStmt:
+		return 1 << nIncDecStmt
+	case *ast.IndexExpr:
+		return 1 << nIndexExpr
+	case *ast.IndexListExpr:
+		return 1 << nIndexListExpr
+	case *ast.InterfaceType:
+		return 1 << nInterfaceType
+	case *ast.KeyValueExpr:
+		return 1 << nKeyValueExpr
+	case *ast.LabeledStmt:
+		return 1 << nLabeledStmt
+	case *ast.MapType:
+		return 1 << nMapType
+	case *ast.Package:
+		return 1 << nPackage
+	case *ast.ParenExpr:
+		return 1 << nParenExpr
+	case *ast.RangeStmt:
+		return 1 << nRangeStmt
+	case *ast.ReturnStmt:
+		return 1 << nReturnStmt
+	case *ast.SelectStmt:
+		return 1 << nSelectStmt
+	case *ast.SelectorExpr:
+		return 1 << nSelectorExpr
+	case *ast.SendStmt:
+		return 1 << nSendStmt
+	case *ast.SliceExpr:
+		return 1 << nSliceExpr
+	case *ast.StarExpr:
+		return 1 << nStarExpr
+	case *ast.StructType:
+		return 1 << nStructType
+	case *ast.SwitchStmt:
+		return 1 << nSwitchStmt
+	case *ast.TypeAssertExpr:
+		return 1 << nTypeAssertExpr
+	case *ast.TypeSpec:
+		return 1 << nTypeSpec
+	case *ast.TypeSwitchStmt:
+		return 1 << nTypeSwitchStmt
+	case *ast.UnaryExpr:
+		return 1 << nUnaryExpr
+	case *ast.ValueSpec:
+		return 1 << nValueSpec
+	}
+	return 0
+}
+
+func maskOf(nodes []ast.Node) uint64 {
+	if len(nodes) == 0 {
+		return math.MaxUint64 // match all node types
+	}
+	var mask uint64
+	for _, n := range nodes {
+		mask |= typeOf(n)
+	}
+	return mask
+}
@@ -0,0 +1,341 @@
+// 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 inspector
+
+// This file is a fork of ast.Inspect to reduce unnecessary dynamic
+// calls and to gather edge information.
+//
+// Consistency with the original is ensured by TestInspectAllNodes.
+
+import (
+	"fmt"
+	"go/ast"
+
+	"golang.org/x/tools/go/ast/edge"
+)
+
+func walkList[N ast.Node](v *visitor, ek edge.Kind, list []N) {
+	for i, node := range list {
+		walk(v, ek, i, node)
+	}
+}
+
+func walk(v *visitor, ek edge.Kind, index int, node ast.Node) {
+	v.push(ek, index, node)
+
+	// walk children
+	// (the order of the cases matches the order
+	// of the corresponding node types in ast.go)
+	switch n := node.(type) {
+	// Comments and fields
+	case *ast.Comment:
+		// nothing to do
+
+	case *ast.CommentGroup:
+		walkList(v, edge.CommentGroup_List, n.List)
+
+	case *ast.Field:
+		if n.Doc != nil {
+			walk(v, edge.Field_Doc, -1, n.Doc)
+		}
+		walkList(v, edge.Field_Names, n.Names)
+		if n.Type != nil {
+			walk(v, edge.Field_Type, -1, n.Type)
+		}
+		if n.Tag != nil {
+			walk(v, edge.Field_Tag, -1, n.Tag)
+		}
+		if n.Comment != nil {
+			walk(v, edge.Field_Comment, -1, n.Comment)
+		}
+
+	case *ast.FieldList:
+		walkList(v, edge.FieldList_List, n.List)
+
+	// Expressions
+	case *ast.BadExpr, *ast.Ident, *ast.BasicLit:
+		// nothing to do
+
+	case *ast.Ellipsis:
+		if n.Elt != nil {
+			walk(v, edge.Ellipsis_Elt, -1, n.Elt)
+		}
+
+	case *ast.FuncLit:
+		walk(v, edge.FuncLit_Type, -1, n.Type)
+		walk(v, edge.FuncLit_Body, -1, n.Body)
+
+	case *ast.CompositeLit:
+		if n.Type != nil {
+			walk(v, edge.CompositeLit_Type, -1, n.Type)
+		}
+		walkList(v, edge.CompositeLit_Elts, n.Elts)
+
+	case *ast.ParenExpr:
+		walk(v, edge.ParenExpr_X, -1, n.X)
+
+	case *ast.SelectorExpr:
+		walk(v, edge.SelectorExpr_X, -1, n.X)
+		walk(v, edge.SelectorExpr_Sel, -1, n.Sel)
+
+	case *ast.IndexExpr:
+		walk(v, edge.IndexExpr_X, -1, n.X)
+		walk(v, edge.IndexExpr_Index, -1, n.Index)
+
+	case *ast.IndexListExpr:
+		walk(v, edge.IndexListExpr_X, -1, n.X)
+		walkList(v, edge.IndexListExpr_Indices, n.Indices)
+
+	case *ast.SliceExpr:
+		walk(v, edge.SliceExpr_X, -1, n.X)
+		if n.Low != nil {
+			walk(v, edge.SliceExpr_Low, -1, n.Low)
+		}
+		if n.High != nil {
+			walk(v, edge.SliceExpr_High, -1, n.High)
+		}
+		if n.Max != nil {
+			walk(v, edge.SliceExpr_Max, -1, n.Max)
+		}
+
+	case *ast.TypeAssertExpr:
+		walk(v, edge.TypeAssertExpr_X, -1, n.X)
+		if n.Type != nil {
+			walk(v, edge.TypeAssertExpr_Type, -1, n.Type)
+		}
+
+	case *ast.CallExpr:
+		walk(v, edge.CallExpr_Fun, -1, n.Fun)
+		walkList(v, edge.CallExpr_Args, n.Args)
+
+	case *ast.StarExpr:
+		walk(v, edge.StarExpr_X, -1, n.X)
+
+	case *ast.UnaryExpr:
+		walk(v, edge.UnaryExpr_X, -1, n.X)
+
+	case *ast.BinaryExpr:
+		walk(v, edge.BinaryExpr_X, -1, n.X)
+		walk(v, edge.BinaryExpr_Y, -1, n.Y)
+
+	case *ast.KeyValueExpr:
+		walk(v, edge.KeyValueExpr_Key, -1, n.Key)
+		walk(v, edge.KeyValueExpr_Value, -1, n.Value)
+
+	// Types
+	case *ast.ArrayType:
+		if n.Len != nil {
+			walk(v, edge.ArrayType_Len, -1, n.Len)
+		}
+		walk(v, edge.ArrayType_Elt, -1, n.Elt)
+
+	case *ast.StructType:
+		walk(v, edge.StructType_Fields, -1, n.Fields)
+
+	case *ast.FuncType:
+		if n.TypeParams != nil {
+			walk(v, edge.FuncType_TypeParams, -1, n.TypeParams)
+		}
+		if n.Params != nil {
+			walk(v, edge.FuncType_Params, -1, n.Params)
+		}
+		if n.Results != nil {
+			walk(v, edge.FuncType_Results, -1, n.Results)
+		}
+
+	case *ast.InterfaceType:
+		walk(v, edge.InterfaceType_Methods, -1, n.Methods)
+
+	case *ast.MapType:
+		walk(v, edge.MapType_Key, -1, n.Key)
+		walk(v, edge.MapType_Value, -1, n.Value)
+
+	case *ast.ChanType:
+		walk(v, edge.ChanType_Value, -1, n.Value)
+
+	// Statements
+	case *ast.BadStmt:
+		// nothing to do
+
+	case *ast.DeclStmt:
+		walk(v, edge.DeclStmt_Decl, -1, n.Decl)
+
+	case *ast.EmptyStmt:
+		// nothing to do
+
+	case *ast.LabeledStmt:
+		walk(v, edge.LabeledStmt_Label, -1, n.Label)
+		walk(v, edge.LabeledStmt_Stmt, -1, n.Stmt)
+
+	case *ast.ExprStmt:
+		walk(v, edge.ExprStmt_X, -1, n.X)
+
+	case *ast.SendStmt:
+		walk(v, edge.SendStmt_Chan, -1, n.Chan)
+		walk(v, edge.SendStmt_Value, -1, n.Value)
+
+	case *ast.IncDecStmt:
+		walk(v, edge.IncDecStmt_X, -1, n.X)
+
+	case *ast.AssignStmt:
+		walkList(v, edge.AssignStmt_Lhs, n.Lhs)
+		walkList(v, edge.AssignStmt_Rhs, n.Rhs)
+
+	case *ast.GoStmt:
+		walk(v, edge.GoStmt_Call, -1, n.Call)
+
+	case *ast.DeferStmt:
+		walk(v, edge.DeferStmt_Call, -1, n.Call)
+
+	case *ast.ReturnStmt:
+		walkList(v, edge.ReturnStmt_Results, n.Results)
+
+	case *ast.BranchStmt:
+		if n.Label != nil {
+			walk(v, edge.BranchStmt_Label, -1, n.Label)
+		}
+
+	case *ast.BlockStmt:
+		walkList(v, edge.BlockStmt_List, n.List)
+
+	case *ast.IfStmt:
+		if n.Init != nil {
+			walk(v, edge.IfStmt_Init, -1, n.Init)
+		}
+		walk(v, edge.IfStmt_Cond, -1, n.Cond)
+		walk(v, edge.IfStmt_Body, -1, n.Body)
+		if n.Else != nil {
+			walk(v, edge.IfStmt_Else, -1, n.Else)
+		}
+
+	case *ast.CaseClause:
+		walkList(v, edge.CaseClause_List, n.List)
+		walkList(v, edge.CaseClause_Body, n.Body)
+
+	case *ast.SwitchStmt:
+		if n.Init != nil {
+			walk(v, edge.SwitchStmt_Init, -1, n.Init)
+		}
+		if n.Tag != nil {
+			walk(v, edge.SwitchStmt_Tag, -1, n.Tag)
+		}
+		walk(v, edge.SwitchStmt_Body, -1, n.Body)
+
+	case *ast.TypeSwitchStmt:
+		if n.Init != nil {
+			walk(v, edge.TypeSwitchStmt_Init, -1, n.Init)
+		}
+		walk(v, edge.TypeSwitchStmt_Assign, -1, n.Assign)
+		walk(v, edge.TypeSwitchStmt_Body, -1, n.Body)
+
+	case *ast.CommClause:
+		if n.Comm != nil {
+			walk(v, edge.CommClause_Comm, -1, n.Comm)
+		}
+		walkList(v, edge.CommClause_Body, n.Body)
+
+	case *ast.SelectStmt:
+		walk(v, edge.SelectStmt_Body, -1, n.Body)
+
+	case *ast.ForStmt:
+		if n.Init != nil {
+			walk(v, edge.ForStmt_Init, -1, n.Init)
+		}
+		if n.Cond != nil {
+			walk(v, edge.ForStmt_Cond, -1, n.Cond)
+		}
+		if n.Post != nil {
+			walk(v, edge.ForStmt_Post, -1, n.Post)
+		}
+		walk(v, edge.ForStmt_Body, -1, n.Body)
+
+	case *ast.RangeStmt:
+		if n.Key != nil {
+			walk(v, edge.RangeStmt_Key, -1, n.Key)
+		}
+		if n.Value != nil {
+			walk(v, edge.RangeStmt_Value, -1, n.Value)
+		}
+		walk(v, edge.RangeStmt_X, -1, n.X)
+		walk(v, edge.RangeStmt_Body, -1, n.Body)
+
+	// Declarations
+	case *ast.ImportSpec:
+		if n.Doc != nil {
+			walk(v, edge.ImportSpec_Doc, -1, n.Doc)
+		}
+		if n.Name != nil {
+			walk(v, edge.ImportSpec_Name, -1, n.Name)
+		}
+		walk(v, edge.ImportSpec_Path, -1, n.Path)
+		if n.Comment != nil {
+			walk(v, edge.ImportSpec_Comment, -1, n.Comment)
+		}
+
+	case *ast.ValueSpec:
+		if n.Doc != nil {
+			walk(v, edge.ValueSpec_Doc, -1, n.Doc)
+		}
+		walkList(v, edge.ValueSpec_Names, n.Names)
+		if n.Type != nil {
+			walk(v, edge.ValueSpec_Type, -1, n.Type)
+		}
+		walkList(v, edge.ValueSpec_Values, n.Values)
+		if n.Comment != nil {
+			walk(v, edge.ValueSpec_Comment, -1, n.Comment)
+		}
+
+	case *ast.TypeSpec:
+		if n.Doc != nil {
+			walk(v, edge.TypeSpec_Doc, -1, n.Doc)
+		}
+		walk(v, edge.TypeSpec_Name, -1, n.Name)
+		if n.TypeParams != nil {
+			walk(v, edge.TypeSpec_TypeParams, -1, n.TypeParams)
+		}
+		walk(v, edge.TypeSpec_Type, -1, n.Type)
+		if n.Comment != nil {
+			walk(v, edge.TypeSpec_Comment, -1, n.Comment)
+		}
+
+	case *ast.BadDecl:
+		// nothing to do
+
+	case *ast.GenDecl:
+		if n.Doc != nil {
+			walk(v, edge.GenDecl_Doc, -1, n.Doc)
+		}
+		walkList(v, edge.GenDecl_Specs, n.Specs)
+
+	case *ast.FuncDecl:
+		if n.Doc != nil {
+			walk(v, edge.FuncDecl_Doc, -1, n.Doc)
+		}
+		if n.Recv != nil {
+			walk(v, edge.FuncDecl_Recv, -1, n.Recv)
+		}
+		walk(v, edge.FuncDecl_Name, -1, n.Name)
+		walk(v, edge.FuncDecl_Type, -1, n.Type)
+		if n.Body != nil {
+			walk(v, edge.FuncDecl_Body, -1, n.Body)
+		}
+
+	case *ast.File:
+		if n.Doc != nil {
+			walk(v, edge.File_Doc, -1, n.Doc)
+		}
+		walk(v, edge.File_Name, -1, n.Name)
+		walkList(v, edge.File_Decls, n.Decls)
+		// don't walk n.Comments - they have been
+		// visited already through the individual
+		// nodes
+
+	default:
+		// (includes *ast.Package)
+		panic(fmt.Sprintf("Walk: unexpected node type %T", n))
+	}
+
+	v.pop(node)
+}
@@ -364,12 +364,6 @@ type jsonPackage struct {
 	DepsErrors []*packagesinternal.PackageError
 }

-type jsonPackageError struct {
-	ImportStack []string
-	Pos         string
-	Err         string
-}
-
 func otherFiles(p *jsonPackage) [][]string {
 	return [][]string{p.CFiles, p.CXXFiles, p.MFiles, p.HFiles, p.FFiles, p.SFiles, p.SwigFiles, p.SwigCXXFiles, p.SysoFiles}
 }
@@ -28,11 +28,6 @@ type Event struct {
 	dynamic []label.Label  // dynamically sized storage for remaining labels
 }

-// eventLabelMap implements label.Map for a the labels of an Event.
-type eventLabelMap struct {
-	event Event
-}
-
 func (ev Event) At() time.Time { return ev.at }

 func (ev Event) Format(f fmt.State, r rune) {
@@ -569,7 +569,6 @@ func (p *iexporter) exportName(obj types.Object) (res string) {

 type iexporter struct {
 	fset    *token.FileSet
-	out     *bytes.Buffer
 	version int

 	shallow    bool                // don't put types from other packages in the index
@@ -0,0 +1,49 @@
+// 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 typesinternal
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+)
+
+// NoEffects reports whether the expression has no side effects, i.e., it
+// does not modify the memory state. This function is conservative: it may
+// return false even when the expression has no effect.
+func NoEffects(info *types.Info, expr ast.Expr) bool {
+	noEffects := true
+	ast.Inspect(expr, func(n ast.Node) bool {
+		switch v := n.(type) {
+		case nil, *ast.Ident, *ast.BasicLit, *ast.BinaryExpr, *ast.ParenExpr,
+			*ast.SelectorExpr, *ast.IndexExpr, *ast.SliceExpr, *ast.TypeAssertExpr,
+			*ast.StarExpr, *ast.CompositeLit, *ast.ArrayType, *ast.StructType,
+			*ast.MapType, *ast.InterfaceType, *ast.KeyValueExpr:
+			// No effect
+		case *ast.UnaryExpr:
+			// Channel send <-ch has effects
+			if v.Op == token.ARROW {
+				noEffects = false
+			}
+		case *ast.CallExpr:
+			// Type conversion has no effects
+			if !info.Types[v.Fun].IsType() {
+				// TODO(adonovan): Add a case for built-in functions without side
+				// effects (by using callsPureBuiltin from tools/internal/refactor/inline)
+
+				noEffects = false
+			}
+		case *ast.FuncLit:
+			// A FuncLit has no effects, but do not descend into it.
+			return false
+		default:
+			// All other expressions have effects
+			noEffects = false
+		}
+
+		return noEffects
+	})
+	return noEffects
+}
@@ -0,0 +1,71 @@
+// 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 typesinternal
+
+import (
+	"go/types"
+	"slices"
+)
+
+// IsTypeNamed reports whether t is (or is an alias for) a
+// package-level defined type with the given package path and one of
+// the given names. It returns false if t is nil.
+//
+// This function avoids allocating the concatenation of "pkg.Name",
+// which is important for the performance of syntax matching.
+func IsTypeNamed(t types.Type, pkgPath string, names ...string) bool {
+	if named, ok := types.Unalias(t).(*types.Named); ok {
+		tname := named.Obj()
+		return tname != nil &&
+			IsPackageLevel(tname) &&
+			tname.Pkg().Path() == pkgPath &&
+			slices.Contains(names, tname.Name())
+	}
+	return false
+}
+
+// IsPointerToNamed reports whether t is (or is an alias for) a pointer to a
+// package-level defined type with the given package path and one of the given
+// names. It returns false if t is not a pointer type.
+func IsPointerToNamed(t types.Type, pkgPath string, names ...string) bool {
+	r := Unpointer(t)
+	if r == t {
+		return false
+	}
+	return IsTypeNamed(r, pkgPath, names...)
+}
+
+// IsFunctionNamed reports whether obj is a package-level function
+// defined in the given package and has one of the given names.
+// It returns false if obj is nil.
+//
+// This function avoids allocating the concatenation of "pkg.Name",
+// which is important for the performance of syntax matching.
+func IsFunctionNamed(obj types.Object, pkgPath string, names ...string) bool {
+	f, ok := obj.(*types.Func)
+	return ok &&
+		IsPackageLevel(obj) &&
+		f.Pkg().Path() == pkgPath &&
+		f.Type().(*types.Signature).Recv() == nil &&
+		slices.Contains(names, f.Name())
+}
+
+// IsMethodNamed reports whether obj is a method defined on a
+// package-level type with the given package and type name, and has
+// one of the given names. It returns false if obj is nil.
+//
+// This function avoids allocating the concatenation of "pkg.TypeName.Name",
+// which is important for the performance of syntax matching.
+func IsMethodNamed(obj types.Object, pkgPath string, typeName string, names ...string) bool {
+	if fn, ok := obj.(*types.Func); ok {
+		if recv := fn.Type().(*types.Signature).Recv(); recv != nil {
+			_, T := ReceiverNamed(recv)
+			return T != nil &&
+				IsTypeNamed(T, pkgPath, typeName) &&
+				slices.Contains(names, fn.Name())
+		}
+	}
+	return false
+}
@@ -15,6 +15,14 @@ import (
 // file.
 // If the same package is imported multiple times, the last appearance is
 // recorded.
+//
+// TODO(adonovan): this function ignores the effect of shadowing. It
+// should accept a [token.Pos] and a [types.Info] and compute only the
+// set of imports that are not shadowed at that point, analogous to
+// [analysisinternal.AddImport]. It could also compute (as a side
+// effect) the set of additional imports required to ensure that there
+// is an accessible import for each necessary package, making it
+// converge even more closely with AddImport.
 func FileQualifier(f *ast.File, pkg *types.Package) types.Qualifier {
 	// Construct mapping of import paths to their defined names.
 	// It is only necessary to look at renaming imports.
@@ -2,8 +2,20 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

-// Package typesinternal provides access to internal go/types APIs that are not
-// yet exported.
+// Package typesinternal provides helpful operators for dealing with
+// go/types:
+//
+//   - operators for querying typed syntax trees (e.g. [Imports], [IsFunctionNamed]);
+//   - functions for converting types to strings or syntax (e.g. [TypeExpr], FileQualifier]);
+//   - helpers for working with the [go/types] API (e.g. [NewTypesInfo]);
+//   - access to internal go/types APIs that are not yet
+//     exported (e.g. [SetUsesCgo], [ErrorCodeStartEnd], [VarKind]); and
+//   - common algorithms related to types (e.g. [TooNewStdSymbols]).
+//
+// See also:
+//   - [golang.org/x/tools/internal/astutil], for operations on untyped syntax;
+//   - [golang.org/x/tools/internal/analysisinernal], for helpers for analyzers;
+//   - [golang.org/x/tools/internal/refactor], for operators to compute text edits.
 package typesinternal

 import (
@@ -13,6 +25,7 @@ import (
 	"reflect"
 	"unsafe"

+	"golang.org/x/tools/go/ast/inspector"
 	"golang.org/x/tools/internal/aliases"
 )

@@ -60,6 +73,9 @@ func ErrorCodeStartEnd(err types.Error) (code ErrorCode, start, end token.Pos, o
 // which is often excessive.)
 //
 // If pkg is nil, it is equivalent to [*types.Package.Name].
+//
+// TODO(adonovan): all uses of this with TypeString should be
+// eliminated when https://go.dev/issues/75604 is resolved.
 func NameRelativeTo(pkg *types.Package) types.Qualifier {
 	return func(other *types.Package) string {
 		if pkg != nil && pkg == other {
@@ -153,3 +169,31 @@ func NewTypesInfo() *types.Info {
 		FileVersions: map[*ast.File]string{},
 	}
 }
+
+// EnclosingScope returns the innermost block logically enclosing the cursor.
+func EnclosingScope(info *types.Info, cur inspector.Cursor) *types.Scope {
+	for cur := range cur.Enclosing() {
+		n := cur.Node()
+		// A function's Scope is associated with its FuncType.
+		switch f := n.(type) {
+		case *ast.FuncDecl:
+			n = f.Type
+		case *ast.FuncLit:
+			n = f.Type
+		}
+		if b := info.Scopes[n]; b != nil {
+			return b
+		}
+	}
+	panic("no Scope for *ast.File")
+}
+
+// Imports reports whether path is imported by pkg.
+func Imports(pkg *types.Package, path string) bool {
+	for _, imp := range pkg.Imports() {
+		if imp.Path() == path {
+			return true
+		}
+	}
+	return false
+}
@@ -204,23 +204,12 @@ func ZeroExpr(t types.Type, qual types.Qualifier) (_ ast.Expr, isValid bool) {
 	}
 }

-// IsZeroExpr uses simple syntactic heuristics to report whether expr
-// is a obvious zero value, such as 0, "", nil, or false.
-// It cannot do better without type information.
-func IsZeroExpr(expr ast.Expr) bool {
-	switch e := expr.(type) {
-	case *ast.BasicLit:
-		return e.Value == "0" || e.Value == `""`
-	case *ast.Ident:
-		return e.Name == "nil" || e.Name == "false"
-	default:
-		return false
-	}
-}
-
 // TypeExpr returns syntax for the specified type. References to named types
 // are qualified by an appropriate (optional) qualifier function.
 // It may panic for types such as Tuple or Union.
+//
+// See also https://go.dev/issues/75604, which will provide a robust
+// Type-to-valid-Go-syntax formatter.
 func TypeExpr(t types.Type, qual types.Qualifier) ast.Expr {
 	switch t := t.(type) {
 	case *types.Basic: