Release模式下CS8795错误：带访问修饰符的分部方法需实现

Severity Code Description Project File Line Suppression State
Error (active) CS8795 Partial method 'MyContactsService.GetContactsAsync()' must have an implementation part because it has accessibility modifiers. ContactsDemo (net8.0-maccatalyst), ContactsDemo (net8.0-windows10.0.19041.0)

该错误导致无法生成APK文件，我通过一个服务类获取本地通讯录联系人，引发错误的共享代码如下：

namespace ContactsDemo.Service
{
    public partial class MyContactsService
    {
        public partial List<MyContact> GetContactsAsync();
    }
}

我已在Android和iOS平台分别实现了该服务类：

Android平台服务实现 #

namespace ContactsDemo.Service
{
    public partial class MyContactsService 
    {
        const string ThumbnailPrefix = "thumb";
        List<MyContact> contactList;
        public partial List<MyContact> GetContactsAsync()
        {
            FillContacts();
            return contactList;
        }

        void FillContacts()
        {
            var uri = ContactsContract.Contacts.ContentUri;

            string[] projection = {
                ContactsContract.Contacts.InterfaceConsts.Id,
                ContactsContract.Contacts.InterfaceConsts.DisplayName,
                ContactsContract.Contacts.InterfaceConsts.PhotoId,
            };


            var ctx = Android.App.Application.Context;

            var cursor = ctx.ApplicationContext.ContentResolver.Query(uri, new string[]
{
                        ContactsContract.Contacts.InterfaceConsts.Id,
                        ContactsContract.Contacts.InterfaceConsts.DisplayName,
                        ContactsContract.Contacts.InterfaceConsts.PhotoThumbnailUri
}, null, null, $"{ContactsContract.Contacts.InterfaceConsts.DisplayName} ASC");

            contactList = new List<MyContact>();

            if (cursor.MoveToFirst())
            {
                do
                {
                    var contact = CreateContact(cursor, ctx);
                    if (!string.IsNullOrWhiteSpace(contact.Name))
                    {
                        contactList.Add(contact);
                    }
                } while (cursor.MoveToNext());
            }
        }

        MyContact CreateContact(ICursor cursor, Context ctx)
        {
            var contactId = GetString(cursor, ContactsContract.Contacts.InterfaceConsts.Id);

            var numbers = GetNumbers(ctx, contactId);
            var emails = GetEmails(ctx, contactId);

            var uri = GetString(cursor, ContactsContract.Contacts.InterfaceConsts.PhotoThumbnailUri);
            string path = null;
            if (!string.IsNullOrEmpty(uri))
            {
                try
                {
                    using (var stream = Android.App.Application.Context.ContentResolver.OpenInputStream(Android.Net.Uri.Parse(uri)))
                    {
                        path = Path.Combine(Path.GetTempPath(), $"{ThumbnailPrefix}-{Guid.NewGuid()}");
                        using (var fstream = new FileStream(path, FileMode.Create))
                        {
                            stream.CopyTo(fstream);
                            fstream.Close();
                        }

                        stream.Close();
                    }


                }
                catch (Exception ex)
                {
                    System.Diagnostics.Debug.WriteLine(ex);
                }

            }
            var contact = new MyContact
            {
                Name = GetString(cursor, ContactsContract.Contacts.InterfaceConsts.DisplayName),
                Emails = emails,
                Image = path,
                PhoneNumbers = numbers,
            };

            return contact;
        }

        string[] GetNumbers(Context ctx, string contactId)
        {
            var key = ContactsContract.CommonDataKinds.Phone.Number;

            var cursor = ctx.ApplicationContext.ContentResolver.Query(
                ContactsContract.CommonDataKinds.Phone.ContentUri,
                null,
                ContactsContract.CommonDataKinds.Phone.InterfaceConsts.ContactId + " = ?",
                new[] { contactId },
                null
            );

            return ReadCursorItems(cursor, key)?.ToArray();
        }

        string[] GetEmails(Context ctx, string contactId)
        {
            var key = ContactsContract.CommonDataKinds.Email.InterfaceConsts.Data;

            var cursor = ctx.ApplicationContext.ContentResolver.Query(
                ContactsContract.CommonDataKinds.Email.ContentUri,
                null,
                ContactsContract.CommonDataKinds.Email.InterfaceConsts.ContactId + " = ?",
                new[] { contactId },
                null);

            return ReadCursorItems(cursor, key)?.ToArray();
        }

        IEnumerable<string> ReadCursorItems(ICursor cursor, string key)
        {
            while (cursor.MoveToNext())
            {
                var value = GetString(cursor, key);
                yield return value;
            }

            cursor.Close();
        }

        string GetString(ICursor cursor, string key)
        {
            return cursor.GetString(cursor.GetColumnIndex(key));
        }

    }
}

iOS平台服务实现 #

namespace ContactsDemo.Service
{
    public partial class MyContactsService
    {
        const string ThumbnailPrefix = "thumb";

        List<MyContact> contacts = new List<MyContact>();

        public partial List<MyContact> GetContactsAsync()
        {
            NSError error = null;
            var keysToFetch = new[] { CNContactKey.PhoneNumbers, CNContactKey.GivenName, CNContactKey.FamilyName, CNContactKey.EmailAddresses, CNContactKey.ImageDataAvailable, CNContactKey.ThumbnailImageData };

            var request = new CNContactFetchRequest(keysToFetch: keysToFetch);
            request.SortOrder = CNContactSortOrder.GivenName;

            using (var store = new CNContactStore())
            {
                var result = store.EnumerateContacts(request, out error, new CNContactStoreListContactsHandler((CNContact c, ref bool stop) =>
                {

                    string path = null;
                    if (c.ImageDataAvailable)
                    {
                        path = path = Path.Combine(Path.GetTempPath(), $"{ThumbnailPrefix}-{Guid.NewGuid()}");

                        if (!File.Exists(path))
                        {
                            var imageData = c.ThumbnailImageData;
                            imageData?.Save(path, true);


                        }
                    }

                    var contact = new MyContact()
                    {
                        Name = string.IsNullOrEmpty(c.FamilyName) ? c.GivenName : $"{c.GivenName} {c.FamilyName}",
                        Image = path,
                        PhoneNumbers = c.PhoneNumbers?.Select(p => p?.Value?.StringValue).ToArray(),
                        Emails = c.EmailAddresses?.Select(p => p?.Value?.ToString()).ToArray(),

                    };

                    if (!string.IsNullOrWhiteSpace(contact.Name))
                    {
                        contacts.Add(contact);
                    }
                }));
            }

            return contacts;
        }
    }
}

Debug模式下应用可以正常运行，但Release模式无法重建项目、生成APK。我已创建演示项目用于复现问题。

更新 #

已将Visual Studio正式版和预览版更新至最新版本，但问题依旧。我的VS版本：

• Microsoft Visual Studio Community 2022 (64-bit) - Preview Version 17.11.0 Preview 2.0
• Microsoft Visual Studio Community 2022 (64-bit) - Current Version 17.10.2

内容的提问来源于stack exchange，提问作者Matthew Pans