TokPos token.Pos   // position of Tok
		Tok    token.Token // keyword token (BREAK, CONTINUE, GOTO, FALLTHROUGH)
		Label  *Ident      // label name; or nil
	}

	// A BlockStmt node represents a braced statement list.
	BlockStmt struct {
		Lbrace token.Pos // position of "{"
		List   []Stmt
		Rbrace token.Pos // position of "}", if any (may be absent due to syntax error)
	}

// A rewriter implements rewriting the range-over-funcs in a given function.
type rewriter struct {
	pkg   *types2.Package
	info  *types2.Info
	sig   *types2.Signature
	outer *syntax.FuncType
	body  *syntax.BlockStmt

	// References to important types and values.
	any   types2.Object
	bool  types2.Object
	int   types2.Object
	true  types2.Object
	false types2.Object

	// Branch numbering, computed as needed.

	{name: "for1", format: "package main; func main() { «for x { «» }» }", scope: true, scopeMultiplier: 2},                          // Scopes: ForStmt, BlockStmt
	{name: "for3", format: "package main; func main() { «for f(); g(); h() { «» }» }", scope: true, scopeMultiplier: 2},              // Scopes: ForStmt, BlockStmt

}

// stripOutputComment finds and removes the "Output:" or "Unordered output:"
// comment from body and comments, and adjusts the body block's end position.
func stripOutputComment(body *ast.BlockStmt, comments []*ast.CommentGroup) (*ast.BlockStmt, []*ast.CommentGroup) {
	// Do nothing if there is no "Output:" or "Unordered output:" comment.
	i, last := lastComment(body, comments)
	if last == nil || !outputPrefix.MatchString(last.Text()) {

// z-assignment statement, because it spans three of its children (:=,
// x, +).  So too is the 1-char interval D, because it contains only
// interior whitespace of the assignment.  E is considered interior
// whitespace of the BlockStmt containing the assignment.
//
// The resulting path is never empty; it always contains at least the
// 'root' *ast.File.  Ideally PathEnclosingInterval would reject

		// we inserted above.
		pos := f.fset.File(n.Body.End()).Pos(elseOffset + 4)
		switch stmt := n.Else.(type) {
		case *ast.IfStmt:
			block := &ast.BlockStmt{
				Lbrace: pos,
				List:   []ast.Stmt{stmt},
				Rbrace: stmt.End(),
			}
			n.Else = block
		case *ast.BlockStmt:
			stmt.Lbrace = pos
		default:
			panic("unexpected node type in if")
		}
		ast.Walk(f, n.Else)
		return nil
	case *ast.SelectStmt:

var fixes []fix

func register(f fix) {
	fixes = append(fixes, f)
}

// walk traverses the AST x, calling visit(y) for each node y in the tree but
// also with a pointer to each ast.Expr, ast.Stmt, and *ast.BlockStmt,
// in a bottom-up traversal.
func walk(x any, visit func(any)) {
	walkBeforeAfter(x, nop, visit)
}

func nop(any) {}

// walkBeforeAfter is like walk but calls before(x) before traversing

//   - bad labeled breaks and continues
//   - invalid, unused, duplicate, and missing labels
//   - gotos jumping over variable declarations and into blocks
func checkBranches(body *BlockStmt, errh ErrorHandler) {
	if body == nil {
		return
	}

	// scope of all labels in this body
	ls := &labelScope{errh: errh}
	fwdGotos := ls.blockBranches(nil, targets{}, nil, body.Pos(), body.List)

		addVar := func(expr ast.Expr) {
			if id, _ := expr.(*ast.Ident); id != nil {
				if obj := pass.TypesInfo.ObjectOf(id); obj != nil {
					vars = append(vars, obj)
				}
			}
		}
		var body *ast.BlockStmt
		switch n := n.(type) {
		case *ast.File:
			// Only traverse the file if its goversion is strictly before go1.22.
			goversion := versions.FileVersion(pass.TypesInfo, n)

	// The Scopes mapping does not contain an entry for the
	// function body ([*ast.BlockStmt]); the function's scope is
	// associated with the [*ast.FuncType].
	//
	// The following node types may appear in Scopes:
	//
	//     *ast.File
	//     *ast.FuncType
	//     *ast.TypeSpec
	//     *ast.BlockStmt
	//     *ast.IfStmt
	//     *ast.SwitchStmt
	//     *ast.TypeSwitchStmt
	//     *ast.CaseClause