[core] Fix all the new nullability warnings

This cropped up as netcoreapp3.0 and net5.0 targets were added
to all the libs which compiled profile specific optimisations.

Fun. I don't have regrets about this.

src/BigEndianBigInteger.cs

@@ -128,7 +128,7 @@ public BigEndianBigInteger (int value)
         public int CompareTo (BigEndianBigInteger other)
             => Value.CompareTo (other.Value);
 
-        public override bool Equals (object obj)
+        public override bool Equals (object? obj)
             => obj is BigEndianBigInteger val && Equals (val);
 
         public bool Equals (BigEndianBigInteger other)

src/Directory.Build.props

@@ -5,7 +5,7 @@
     <CI Condition="'$(CI)' == '' and '$(TF_BUILD)' == 'true'">true</CI>
     <CI Condition="'$(CI)' == '' ">false</CI>
 
-    <NoWarn>1701;1702;1591;0419</NoWarn>
+    <NoWarn>1701;1702;1591;0419;netsdk1138</NoWarn>
 
     <LangVersion>8.0</LangVersion>
     <DebugType>portable</DebugType>

src/Directory.Build.targets

@@ -23,6 +23,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)MemoryExtensions.cs" Condition="'$(UseMemoryExtensions)' == 'true'" Link="Linked\%(FileName)%(Extension)" />
     <Compile Include="$(MSBuildThisFileDirectory)BigEndianBigInteger.cs" Link="Linked\%(FileName)%(Extension)" Condition="$(ProjectName) == 'MonoTorrent.Dht' or $(ProjectName) == 'MonoTorrent.Client'" />
     <Compile Include="$(MSBuildThisFileDirectory)ValueStopwatch.cs" Link="Linked\%(FileName)%(Extension)" />
+    <Compile Include="$(MSBuildThisFileDirectory)NullabilityAttributes.cs" Link="Linked\%(FileName)%(Extension)" Condition="'$(TargetFramework)' == 'netstandard2.0'" />
   </ItemGroup>
 
 

src/MonoTorrent.BEncoding/MonoTorrent.BEncoding/BEncodedDictionary.cs

@@ -29,6 +29,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 
 namespace MonoTorrent.BEncoding
@@ -110,7 +111,7 @@ public override bool Equals (object? obj)
                 return false;
 
             foreach (KeyValuePair<BEncodedString, BEncodedValue> keypair in dictionary) {
-                if (!other.TryGetValue (keypair.Key, out BEncodedValue val))
+                if (!other.TryGetValue (keypair.Key, out BEncodedValue? val))
                     return false;
 
                 if (!keypair.Value.Equals (val))
@@ -176,7 +177,7 @@ public void CopyTo (KeyValuePair<BEncodedString, BEncodedValue>[] array, int arr
 
         public BEncodedValue? GetValueOrDefault (BEncodedString key, BEncodedValue? defaultValue)
         {
-            return dictionary.TryGetValue (key, out BEncodedValue value) ? value : defaultValue;
+            return dictionary.TryGetValue (key, out BEncodedValue? value) ? value : defaultValue;
         }
 
         public bool IsReadOnly => false;
@@ -191,7 +192,9 @@ public bool Remove (KeyValuePair<BEncodedString, BEncodedValue> item)
             return dictionary.Remove (item.Key);
         }
 
-        public bool TryGetValue (BEncodedString key, out BEncodedValue value)
+#pragma warning disable 8767
+        public bool TryGetValue (BEncodedString key, [MaybeNullWhen (false)] out BEncodedValue value)
+#pragma warning restore 8767
         {
             return dictionary.TryGetValue (key, out value);
         }

src/MonoTorrent.BEncoding/MonoTorrent.BEncoding/BEncodedList.cs

@@ -99,7 +99,7 @@ public override int LengthInBytes ()
             return length;
         }
 
-        public override bool Equals (object obj)
+        public override bool Equals (object? obj)
         {
             if (!(obj is BEncodedList other))
                 return false;

src/MonoTorrent.BEncoding/MonoTorrent.BEncoding/BEncodedNumber.cs

@@ -108,22 +108,16 @@ public override int LengthInBytes ()
             // Add 2 for the 'i' and 'e'. Special case '0' as we can't Log10 it. Add 1 if the number is negative. Then calculate digits!
             => 2 + (Number == 0 ? 1 : (Number > 0 ? 1 : 2) + (int) Math.Log10 (Math.Abs ((double)Number)));
 
-        public int CompareTo (object other)
+        public int CompareTo (object? other)
         {
             if (other is BEncodedNumber || other is long || other is int)
                 return CompareTo ((BEncodedNumber) other);
 
-            return -1;
-        }
-
-        public int CompareTo (BEncodedNumber other)
-        {
-            if (other == null)
-                throw new ArgumentNullException (nameof (other));
-
-            return Number.CompareTo (other.Number);
+            return 1;
         }
 
+        public int CompareTo (BEncodedNumber? other)
+            => other == null ? 1 : Number.CompareTo (other.Number);
 
         public int CompareTo (long other)
             => Number.CompareTo (other);
@@ -133,7 +127,7 @@ public int CompareTo (long other)
         /// </summary>
         /// <param name="obj"></param>
         /// <returns></returns>
-        public override bool Equals (object obj)
+        public override bool Equals (object? obj)
             => obj is BEncodedNumber obj2 ? Number == obj2.Number : false;
 
         /// <summary>

src/MonoTorrent.BEncoding/MonoTorrent.BEncoding/BEncodedString.cs

@@ -42,11 +42,7 @@ public class BEncodedString : BEncodedValue, IComparable<BEncodedString>, IEquat
     {
         public static readonly BEncodedString Empty = new BEncodedString (ReadOnlyMemory<byte>.Empty);
 
-        public static bool IsNullOrEmpty (
-#if !NETSTANDARD2_0
-            [NotNullWhen (false)]
-#endif
-        BEncodedString? value)
+        public static bool IsNullOrEmpty ([NotNullWhen (false)] BEncodedString? value)
             => value is null || value.Span.IsEmpty;
 
         public static BEncodedString FromMemory (ReadOnlyMemory<byte> buffer)
@@ -61,21 +57,15 @@ public static BEncodedString UrlDecode (string urlEncodedValue)
             return new BEncodedString (new ReadOnlyMemory<byte> (HttpUtility.UrlDecodeToBytes (urlEncodedValue, Encoding.UTF8)));
         }
 
-#if !NETSTANDARD2_0
         [return: NotNullIfNotNull ("value")]
-#endif
         public static implicit operator BEncodedString? (string? value)
             => value is null ? null : (value.Length == 0 ? Empty : new BEncodedString (value));
 
-#if !NETSTANDARD2_0
         [return: NotNullIfNotNull ("value")]
-#endif
         public static implicit operator BEncodedString? (char[]? value)
             => value is null ? null : (value.Length == 0 ? Empty : new BEncodedString (value));
 
-#if !NETSTANDARD2_0
         [return: NotNullIfNotNull ("value")]
-#endif
         public static implicit operator BEncodedString? (byte[]? value)
             => value is null ? null : (value.Length == 0 ? Empty : new BEncodedString (value));
 

src/MonoTorrent.BEncoding/MonoTorrent.BEncoding/HashingReader.cs

@@ -78,7 +78,7 @@ public override int Read (byte[] buffer, int offset, int count)
         public byte[] TransformFinalBlock ()
         {
             algorithm.TransformFinalBlock (read_one_buffer, 0, 0);
-            return algorithm.Hash;
+            return algorithm.Hash!;
         }
 
         public override void Flush ()

src/MonoTorrent.Client/MonoTorrent.Client.Modes/MetadataMode.cs

@@ -181,8 +181,8 @@ protected override void HandleLtMetadataMessage (PeerId id, LTMetadata message)
 
                                 try {
                                     if (this.Settings.AutoSaveLoadMagnetLinkMetadata) {
-                                        if (!Directory.Exists (Path.GetDirectoryName (savePath)))
-                                            Directory.CreateDirectory (Path.GetDirectoryName (savePath));
+                                        if (Path.GetDirectoryName (savePath) is string parentDir && !Directory.Exists (parentDir))
+                                            Directory.CreateDirectory (parentDir);
                                         File.Delete (savePath);
                                         File.WriteAllBytes (savePath, dict.Encode ());
                                     }

src/MonoTorrent.Client/MonoTorrent.Client.RateLimiters/RateLimiterGroup.cs

@@ -42,7 +42,7 @@ public int? PreferredChunkSize {
                 int? preferredChunkSize = null;
                 for (int i = 0; i < limiters.Count; i++)
                     if (limiters[i].PreferredChunkSize.HasValue)
-                        preferredChunkSize = preferredChunkSize.HasValue ? Math.Min (limiters[i].PreferredChunkSize.Value, preferredChunkSize.Value) : limiters[i].PreferredChunkSize.Value;
+                        preferredChunkSize = preferredChunkSize.HasValue ? Math.Min (limiters[i].PreferredChunkSize!.Value, preferredChunkSize.Value) : limiters[i].PreferredChunkSize!.Value;
                 return preferredChunkSize;
             }
         }

src/MonoTorrent.Client/MonoTorrent.Client.Tracker/TrackerTier.cs

@@ -122,7 +122,7 @@ internal TrackerTier (Factories factories, IEnumerable<string> trackerUrls)
         {
             var trackerList = new List<ITracker> ();
             foreach (string trackerUrl in trackerUrls) {
-                if (!Uri.TryCreate (trackerUrl, UriKind.Absolute, out Uri result)) {
+                if (!Uri.TryCreate (trackerUrl, UriKind.Absolute, out Uri? result)) {
                     logger.InfoFormatted ("Invalid tracker Url specified: {0}", trackerUrl);
                     continue;
                 }

src/MonoTorrent.Client/MonoTorrent.Client/ClientEngine.cs

@@ -84,11 +84,11 @@ public static async Task<ClientEngine> RestoreStateAsync (ReadOnlyMemory<byte> b
                     foreach (BEncodedDictionary file in (BEncodedList) torrent[nameof (manager.Files)]) {
                         TorrentFileInfo torrentFile;
                         torrentFile = (TorrentFileInfo) manager.Files.Single (t => t.Path == ((BEncodedString) file[nameof (torrentFile.Path)]).Text);
-                        torrentFile.Priority = (Priority) Enum.Parse (typeof (Priority), file[nameof (torrentFile.Priority)].ToString ());
+                        torrentFile.Priority = (Priority) Enum.Parse (typeof (Priority), file[nameof (torrentFile.Priority)].ToString ()!);
                         torrentFile.FullPath = ((BEncodedString) file[nameof (torrentFile.FullPath)]).Text;
                     }
                 } else {
-                    var magnetLink = MagnetLink.Parse (torrent[nameof (manager.MagnetLink)].ToString ());
+                    var magnetLink = MagnetLink.Parse (torrent[nameof (manager.MagnetLink)].ToString ()!);
                     if (streaming)
                         await clientEngine.AddStreamingAsync (magnetLink, saveDirectory, torrentSettings);
                     else
@@ -337,7 +337,7 @@ public async Task<TorrentManager> AddAsync (string metadataPath, string saveDire
 
             var metadataCachePath = Settings.GetMetadataPath (torrent.InfoHashes);
             if (metadataPath != metadataCachePath) {
-                Directory.CreateDirectory (Path.GetDirectoryName (metadataCachePath));
+                Directory.CreateDirectory (Path.GetDirectoryName (metadataCachePath)!);
                 File.Copy (metadataPath, metadataCachePath, true);
             }
             return await AddAsync (null, torrent, saveDirectory, settings);
@@ -369,7 +369,7 @@ public async Task<TorrentManager> AddAsync (Torrent torrent, string saveDirector
             }
 
             var metadataCachePath = Settings.GetMetadataPath (torrent.InfoHashes);
-            Directory.CreateDirectory (Path.GetDirectoryName (metadataCachePath));
+            Directory.CreateDirectory (Path.GetDirectoryName (metadataCachePath)!);
             File.WriteAllBytes (metadataCachePath, editor.ToDictionary ().Encode ());
 
             return await AddAsync (null, torrent, saveDirectory, settings);
@@ -572,12 +572,12 @@ public async Task<ReadOnlyMemory<byte>> DownloadMetadataAsync (MagnetLink magnet
             return data;
         }
 
-        async void HandleLocalPeerFound (object sender, LocalPeerFoundEventArgs args)
+        async void HandleLocalPeerFound (object? sender, LocalPeerFoundEventArgs args)
         {
             try {
                 await MainLoop;
 
-                TorrentManager manager = allTorrents.FirstOrDefault (t => t.InfoHashes.Contains (args.InfoHash));
+                TorrentManager? manager = allTorrents.FirstOrDefault (t => t.InfoHashes.Contains (args.InfoHash));
                 // There's no TorrentManager in the engine
                 if (manager == null)
                     return;
@@ -669,12 +669,11 @@ void RegisterLocalPeerDiscovery (ILocalPeerDiscovery? localPeerDiscovery)
             }
         }
 
-        async void DhtEnginePeersFound (object o, PeersFoundEventArgs e)
+        async void DhtEnginePeersFound (object? o, PeersFoundEventArgs e)
         {
             await MainLoop;
 
-            TorrentManager manager = allTorrents.FirstOrDefault (t => t.InfoHashes.Contains (e.InfoHash));
-
+            TorrentManager? manager = allTorrents.FirstOrDefault (t => t.InfoHashes.Contains (e.InfoHash));
             if (manager == null)
                 return;
 
@@ -688,7 +687,7 @@ async void DhtEnginePeersFound (object o, PeersFoundEventArgs e)
             }
         }
 
-        async void DhtEngineStateChanged (object o, EventArgs e)
+        async void DhtEngineStateChanged (object? o, EventArgs e)
         {
             if (DhtEngine.State != DhtState.Ready)
                 return;
@@ -869,7 +868,7 @@ async ReusableTasks.ReusableTask MaybeSaveDhtNodes ()
             // concurrently.
             using (await dhtNodeLocker.EnterAsync ().ConfigureAwait (false)) {
                 var savePath = Settings.GetDhtNodeCacheFilePath ();
-                var parentDir = Path.GetDirectoryName (savePath);
+                var parentDir = Path.GetDirectoryName (savePath)!;
                 Directory.CreateDirectory (parentDir);
                 File.WriteAllBytes (savePath, nodes.ToArray ());
             }

src/MonoTorrent.Client/MonoTorrent.Client/FastResume/FastResume.cs

@@ -125,21 +125,13 @@ public void Encode (Stream s)
             s.Write (data, 0, data.Length);
         }
 
-#if NETSTANDARD2_0
-        public static bool TryLoad (Stream s, out FastResume? fastResume)
-#else
         public static bool TryLoad (Stream s, [NotNullWhen (true)] out FastResume? fastResume)
-#endif
         {
             fastResume = Load (s);
             return fastResume != null;
         }
 
-#if NETSTANDARD2_0
-        public static bool TryLoad (string fastResumeFilePath, out FastResume? fastResume)
-#else
         public static bool TryLoad (string fastResumeFilePath, [NotNullWhen (true)] out FastResume? fastResume)
-#endif
         {
             fastResume = null;
             try {

src/MonoTorrent.Client/MonoTorrent.Client/Managers/DiskManager.cs

@@ -311,7 +311,7 @@ internal async ReusableTask<bool> GetHashAsync (ITorrentManagerInfo manager, int
 
             await IOLoop;
 
-            if (IncrementalHashes.TryGetValue (ValueTuple.Create (manager, pieceIndex), out IncrementalHashData incrementalHash)) {
+            if (IncrementalHashes.TryGetValue (ValueTuple.Create (manager, pieceIndex), out IncrementalHashData? incrementalHash)) {
                 // Immediately remove it from the dictionary so another thread writing data to using `WriteAsync` can't try to use it
                 IncrementalHashes.Remove (ValueTuple.Create (manager, pieceIndex));
 
@@ -477,7 +477,7 @@ internal async ReusableTask WriteAsync (ITorrentManagerInfo manager, BlockInfo r
 
             try {
                 int pieceIndex = request.PieceIndex;
-                if (!IncrementalHashes.TryGetValue (ValueTuple.Create (manager, pieceIndex), out IncrementalHashData incrementalHash) && request.StartOffset == 0) {
+                if (!IncrementalHashes.TryGetValue (ValueTuple.Create (manager, pieceIndex), out IncrementalHashData? incrementalHash) && request.StartOffset == 0) {
                     incrementalHash = IncrementalHashes[ValueTuple.Create (manager, pieceIndex)] = IncrementalHashCache.Dequeue ();
                     incrementalHash.PrepareForFirstUse (manager, pieceIndex);
                 }

src/MonoTorrent.Client/MonoTorrent.Client/Managers/ListenManager.cs

@@ -82,7 +82,7 @@ public void SetListener (IPeerConnectionListener listener)
             Listener.ConnectionReceived += ConnectionReceived;
         }
 
-        async void ConnectionReceived (object sender, PeerConnectionEventArgs e)
+        async void ConnectionReceived (object? sender, PeerConnectionEventArgs e)
         {
             await ClientEngine.MainLoop;
             var peer = new Peer ("", e.Connection.Uri, EncryptionTypes.All);
@@ -93,7 +93,7 @@ async void ConnectionReceived (object sender, PeerConnectionEventArgs e)
                     return;
                 }
                 if (!e.Connection.IsIncoming) {
-                    var manager = Engine.Torrents.FirstOrDefault (t => t.InfoHashes.Contains (e.InfoHash!));
+                    var manager = Engine.Torrents.FirstOrDefault (t => t.InfoHashes.Contains (e.InfoHash!))!;
                     var id = new PeerId (peer, e.Connection, new MutableBitField (manager.Bitfield.Length).SetAll (false));
                     id.LastMessageSent.Restart ();
                     id.LastMessageReceived.Restart ();

src/MonoTorrent.Client/MonoTorrent.Client/Managers/PeerExchangeManager.cs

@@ -65,7 +65,7 @@ internal PeerExchangeManager (TorrentManager manager, PeerId id)
             manager.OnPeerFound += OnAdd;
         }
 
-        internal void OnAdd (object source, PeerAddedEventArgs e)
+        internal void OnAdd (object? source, PeerAddedEventArgs e)
         {
             addedPeers.Add (e.Peer);
         }

src/MonoTorrent.Client/MonoTorrent.Client/Managers/TorrentManager.cs

@@ -495,7 +495,7 @@ public override string ToString ()
         /// </summary>
         /// <param name="obj"></param>
         /// <returns></returns>
-        public override bool Equals (object obj)
+        public override bool Equals (object? obj)
         {
             return (!(obj is TorrentManager m)) ? false : Equals (m);
         }
@@ -506,7 +506,7 @@ public override bool Equals (object obj)
         /// </summary>
         /// <param name="other"></param>
         /// <returns></returns>
-        public bool Equals (TorrentManager other)
+        public bool Equals (TorrentManager? other)
             => other != null && other.InfoHashes == InfoHashes;
 
         /// <summary>
@@ -965,8 +965,10 @@ internal void RaiseConnectionAttemptFailed (ConnectionAttemptFailedEventArgs arg
 
         internal void UpdateLimiters ()
         {
-            DownloadLimiter.UpdateChunks (Settings.MaximumDownloadSpeed, Monitor.ReceiveRate, ClientEngine.PreferredChunkSize (Engine.Settings.MaximumDownloadSpeed, Settings.MaximumDownloadSpeed));
-            UploadLimiter.UpdateChunks (Settings.MaximumUploadSpeed, Monitor.SendRate, ClientEngine.PreferredChunkSize (Engine.Settings.MaximumUploadSpeed, Settings.MaximumUploadSpeed));
+            if (Engine != null) {
+                DownloadLimiter.UpdateChunks (Settings.MaximumDownloadSpeed, Monitor.ReceiveRate, ClientEngine.PreferredChunkSize (Engine.Settings.MaximumDownloadSpeed, Settings.MaximumDownloadSpeed));
+                UploadLimiter.UpdateChunks (Settings.MaximumUploadSpeed, Monitor.SendRate, ClientEngine.PreferredChunkSize (Engine.Settings.MaximumUploadSpeed, Settings.MaximumUploadSpeed));
+            }
         }
         #endregion Internal Methods
 
@@ -1048,7 +1050,7 @@ internal async ReusableTask MaybeWriteFastResumeAsync ()
 
             await MainLoop.SwitchToThreadpool ();
             var fastResumePath = Engine.Settings.GetFastResumePath (InfoHashes);
-            var parentDirectory = Path.GetDirectoryName (fastResumePath);
+            var parentDirectory = Path.GetDirectoryName (fastResumePath)!;
             Directory.CreateDirectory (parentDirectory);
             File.WriteAllBytes (fastResumePath, fastResumeData);
         }
@@ -1066,7 +1068,7 @@ internal void SetTrackerManager (ITrackerManager manager)
             }
         }
 
-        async void HandleTrackerAnnounceComplete (object o, AnnounceResponseEventArgs e)
+        async void HandleTrackerAnnounceComplete (object? o, AnnounceResponseEventArgs e)
         {
             if (e.Successful) {
                 await ClientEngine.MainLoop;

src/MonoTorrent.Client/MonoTorrent.Client/Managers/TrackerManager.cs

@@ -228,10 +228,10 @@ public async ReusableTask ScrapeAsync (ITracker tracker, CancellationToken token
             await trackerTier.ScrapeAsync (args, tracker, token);
         }
 
-        void RaiseAnnounceComplete (object sender, AnnounceResponseEventArgs args)
+        void RaiseAnnounceComplete (object? sender, AnnounceResponseEventArgs args)
             => AnnounceComplete?.InvokeAsync (this, args);
 
-        void RaiseScrapeComplete (object sender, ScrapeResponseEventArgs args)
+        void RaiseScrapeComplete (object? sender, ScrapeResponseEventArgs args)
             => ScrapeComplete?.InvokeAsync (this, args);
     }
 }