f.walk(&n.Type, ctxType, visit)
		}
	case *ast.FieldList:
		for _, field := range n.List {
			f.walk(field, context, visit)
		}
	case *ast.BadExpr:
	case *ast.Ident:
	case *ast.Ellipsis:
		f.walk(&n.Elt, ctxType, visit)
	case *ast.BasicLit:
	case *ast.FuncLit:
		f.walk(n.Type, ctxType, visit)
		f.walk(n.Body, ctxStmt, visit)
	case *ast.CompositeLit:
		f.walk(&n.Type, ctxType, visit)

	if skip(c) {
		return nil
	}
	name := c.Name.Copy(fn, skip)
	var base AST
	if c.Base != nil {
		base = c.Base.Copy(fn, skip)
	}
	if name == nil && base == nil {
		return fn(c)
	}
	if name == nil {
		name = c.Name
	}
	if base == nil {
		base = c.Base
	}
	c = &Constructor{Name: name, Base: base}
	if r := fn(c); r != nil {
		return r
	}
	return c
}