Downgraded language version to 8

Hasn't seem to cause any issues in older .NET versions yet (only used new syntax features), but this will prevent using most unsupported new features for .NET Standard 2.0

Tapeti/Connection/TapetiChannel.cs

@@ -20,7 +20,7 @@ namespace Tapeti.Connection
     internal class TapetiChannel
     {
         private readonly Func<IModel> modelFactory;
-        private readonly object taskQueueLock = new();
+        private readonly object taskQueueLock = new object();
         private SingleThreadTaskQueue taskQueue;
         private readonly ModelProvider modelProvider;
 

Tapeti/Connection/TapetiClient.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Net;
@@ -50,7 +50,7 @@ namespace Tapeti.Connection
         private readonly HttpClient managementClient;
 
         // These fields must be locked using connectionLock
-        private readonly object connectionLock = new();
+        private readonly object connectionLock = new object();
         private long connectionReference;
         private RabbitMQ.Client.IConnection connection;
         private IModel consumeChannelModel;
@@ -61,12 +61,12 @@ namespace Tapeti.Connection
 
         // These fields are for use in a single TapetiChannel's queue only!
         private ulong lastDeliveryTag;
-        private readonly HashSet<string> deletedQueues = new();
+        private readonly HashSet<string> deletedQueues = new HashSet<string>();
 
         // These fields must be locked using confirmLock, since the callbacks for BasicAck/BasicReturn can run in a different thread
-        private readonly object confirmLock = new();
-        private readonly Dictionary<ulong, ConfirmMessageInfo> confirmMessages = new();
-        private readonly Dictionary<string, ReturnInfo> returnRoutingKeys = new();
+        private readonly object confirmLock = new object();
+        private readonly Dictionary<ulong, ConfirmMessageInfo> confirmMessages = new Dictionary<ulong, ConfirmMessageInfo>();
+        private readonly Dictionary<string, ReturnInfo> returnRoutingKeys = new Dictionary<string, ReturnInfo>();
 
 
         private class ConfirmMessageInfo
@@ -184,18 +184,15 @@ namespace Tapeti.Connection
 
                 var replyCode = publishResultTask.Result;
 
-                switch (replyCode)
-                {
-                    // There is no RabbitMQ.Client.Framing.Constants value for this "No route" reply code
-                    // at the time of writing...
-                    case 312:
-                        throw new NoRouteException(
-                            $"Mandatory message with exchange '{exchange}' and routing key '{routingKey}' does not have a route");
-                    
-                    case > 0:
-                        throw new NoRouteException(
-                            $"Mandatory message with exchange '{exchange}' and routing key '{routingKey}' could not be delivered, reply code: {replyCode}");
-                }
+                // There is no RabbitMQ.Client.Framing.Constants value for this "No route" reply code
+                // at the time of writing...
+                if (replyCode == 312)
+                    throw new NoRouteException(
+                        $"Mandatory message with exchange '{exchange}' and routing key '{routingKey}' does not have a route");
+
+                if (replyCode > 0)
+                    throw new NoRouteException(
+                        $"Mandatory message with exchange '{exchange}' and routing key '{routingKey}' could not be delivered, reply code: {replyCode}");
             });
         }
 
@@ -526,7 +523,7 @@ namespace Tapeti.Connection
         }
 
 
-        private static readonly List<HttpStatusCode> TransientStatusCodes = new()
+        private static readonly List<HttpStatusCode> TransientStatusCodes = new List<HttpStatusCode>()
         {
             HttpStatusCode.GatewayTimeout,
             HttpStatusCode.RequestTimeout,
@@ -663,7 +660,7 @@ namespace Tapeti.Connection
                 }
                 catch (WebException e)
                 {
-                    if (e.Response is not HttpWebResponse response)
+                    if (!(e.Response is HttpWebResponse response))
                         throw;
 
                     if (!TransientStatusCodes.Contains(response.StatusCode))
@@ -678,7 +675,7 @@ namespace Tapeti.Connection
         }
 
 
-        private readonly HashSet<string> declaredExchanges = new();
+        private readonly HashSet<string> declaredExchanges = new HashSet<string>();
 
         private void DeclareExchange(IModel channel, string exchange)
         {
@@ -845,7 +842,7 @@ namespace Tapeti.Connection
                             GetTapetiChannel(TapetiChannelType.Consume).QueueRetryable(_ => { });
                     };
 
-                    capturedPublishChannelModel.ModelShutdown += (_, _) =>
+                    capturedPublishChannelModel.ModelShutdown += (sender, args) =>
                     {
                         lock (connectionLock)
                         {

Tapeti/Connection/TapetiConsumer.cs

@@ -172,7 +172,8 @@ namespace Tapeti.Connection
             return e switch
             {
                 AggregateException aggregateException => aggregateException.InnerExceptions.Any(IgnoreExceptionDuringShutdown),
-                TaskCanceledException or OperationCanceledException => true,
+                TaskCanceledException _ => true,
+                OperationCanceledException _ => true,
                 _ => e.InnerException != null && IgnoreExceptionDuringShutdown(e.InnerException)
             };
         }

Tapeti/Connection/TapetiSubscriber.cs

@@ -13,7 +13,7 @@ namespace Tapeti.Connection
         private readonly Func<ITapetiClient> clientFactory;
         private readonly ITapetiConfig config;
         private bool consuming;
-        private readonly List<TapetiConsumerTag> consumerTags = new();
+        private readonly List<TapetiConsumerTag> consumerTags = new List<TapetiConsumerTag>();
 
         private CancellationTokenSource initializeCancellationTokenSource;
 
@@ -167,7 +167,7 @@ namespace Tapeti.Connection
                 public List<Type> MessageClasses;
             }
 
-            private readonly Dictionary<string, List<DynamicQueueInfo>> dynamicQueues = new();
+            private readonly Dictionary<string, List<DynamicQueueInfo>> dynamicQueues = new Dictionary<string, List<DynamicQueueInfo>>();
 
 
             protected CustomBindingTarget(Func<ITapetiClient> clientFactory, IRoutingKeyStrategy routingKeyStrategy, IExchangeStrategy exchangeStrategy, CancellationToken cancellationToken)
@@ -278,8 +278,8 @@ namespace Tapeti.Connection
 
         private class DeclareDurableQueuesBindingTarget : CustomBindingTarget
         {
-            private readonly Dictionary<string, List<Type>> durableQueues = new();
-            private readonly HashSet<string> obsoleteDurableQueues = new();
+            private readonly Dictionary<string, List<Type>> durableQueues = new Dictionary<string, List<Type>>();
+            private readonly HashSet<string> obsoleteDurableQueues = new HashSet<string>();
 
 
             public DeclareDurableQueuesBindingTarget(Func<ITapetiClient> clientFactory, IRoutingKeyStrategy routingKeyStrategy, IExchangeStrategy exchangeStrategy, CancellationToken cancellationToken) : base(clientFactory, routingKeyStrategy, exchangeStrategy, cancellationToken)
@@ -359,7 +359,7 @@ namespace Tapeti.Connection
 
         private class PassiveDurableQueuesBindingTarget : CustomBindingTarget
         {
-            private readonly HashSet<string> durableQueues = new();
+            private readonly HashSet<string> durableQueues = new HashSet<string>();
 
 
             public PassiveDurableQueuesBindingTarget(Func<ITapetiClient> clientFactory, IRoutingKeyStrategy routingKeyStrategy, IExchangeStrategy exchangeStrategy, CancellationToken cancellationToken) : base(clientFactory, routingKeyStrategy, exchangeStrategy, cancellationToken)

Tapeti/Default/ControllerBindingContext.cs

@@ -9,7 +9,7 @@ namespace Tapeti.Default
     internal class ControllerBindingContext : IControllerBindingContext
     {
         private BindingTargetMode? bindingTargetMode;
-        private readonly List<IControllerMiddlewareBase> middleware = new();
+        private readonly List<IControllerMiddlewareBase> middleware = new List<IControllerMiddlewareBase>();
         private readonly List<ControllerBindingParameter> parameters;
         private readonly ControllerBindingResult result;
 

Tapeti/Default/JsonMessageSerializer.cs

@@ -16,8 +16,8 @@ namespace Tapeti.Default
         private const string ClassTypeHeader = "classType";
 
 
-        private readonly ConcurrentDictionary<string, Type> deserializedTypeNames = new();
-        private readonly ConcurrentDictionary<Type, string> serializedTypeNames = new();
+        private readonly ConcurrentDictionary<string, Type> deserializedTypeNames = new ConcurrentDictionary<string, Type>();
+        private readonly ConcurrentDictionary<Type, string> serializedTypeNames = new ConcurrentDictionary<Type, string>();
         private readonly JsonSerializerSettings serializerSettings;
 
 
@@ -49,7 +49,7 @@ namespace Tapeti.Default
         /// <inheritdoc />
         public object Deserialize(byte[] body, IMessageProperties properties)
         {
-            if (properties.ContentType is not ContentType)
+            if (!(properties.ContentType is ContentType))
                 throw new ArgumentException($"content_type must be {ContentType}");
 
             var typeName = properties.GetHeader(ClassTypeHeader);

Tapeti/Default/MessageContext.cs

@@ -8,7 +8,7 @@ namespace Tapeti.Default
 {
     internal class MessageContext : IMessageContext
     {
-        private readonly Dictionary<Type, IMessageContextPayload> payloads = new();
+        private readonly Dictionary<Type, IMessageContextPayload> payloads = new Dictionary<Type, IMessageContextPayload>();
 
 
         /// <inheritdoc />
@@ -117,7 +117,7 @@ namespace Tapeti.Default
         // ReSharper disable once InconsistentNaming
         public class KeyValuePayload : IMessageContextPayload, IDisposable, IAsyncDisposable
         {
-            private readonly Dictionary<string, object> items = new();
+            private readonly Dictionary<string, object> items = new Dictionary<string, object>();
             
             
             public KeyValuePayload(string key, object value)

Tapeti/Default/MessageProperties.cs

@@ -10,7 +10,7 @@ namespace Tapeti.Default
     /// </summary>
     public class MessageProperties : IMessageProperties
     {
-        private readonly Dictionary<string, string> headers = new();
+        private readonly Dictionary<string, string> headers = new Dictionary<string, string>();
 
 
         /// <inheritdoc />

Tapeti/Default/NamespaceMatchExchangeStrategy.cs

@@ -13,7 +13,7 @@ namespace Tapeti.Default
     /// </example>
     public class NamespaceMatchExchangeStrategy : IExchangeStrategy
     {
-        private static readonly Regex NamespaceRegex = new("^(Messaging\\.)?(?<exchange>[^\\.]+)", RegexOptions.Compiled | RegexOptions.Singleline);
+        private static readonly Regex NamespaceRegex = new Regex("^(Messaging\\.)?(?<exchange>[^\\.]+)", RegexOptions.Compiled | RegexOptions.Singleline);
 
 
         /// <inheritdoc />

Tapeti/Default/TypeNameRoutingKeyStrategy.cs

@@ -28,9 +28,9 @@ namespace Tapeti.Default
                     (?(?<=[A-Z])[A-Z](?=[a-z])|[A-Z])
                 )";
 
-        private static readonly Regex SeparatorRegex = new(SeparatorPattern, RegexOptions.IgnorePatternWhitespace | RegexOptions.Compiled);
+        private static readonly Regex SeparatorRegex = new Regex(SeparatorPattern, RegexOptions.IgnorePatternWhitespace | RegexOptions.Compiled);
 
-        private static readonly ConcurrentDictionary<Type, string> RoutingKeyCache = new();
+        private static readonly ConcurrentDictionary<Type, string> RoutingKeyCache = new ConcurrentDictionary<Type, string>();
 
 
         /// <inheritdoc />

Tapeti/Helpers/ConnectionstringParser.cs

@@ -10,7 +10,7 @@ namespace Tapeti.Helpers
     /// </summary>
     public class ConnectionStringParser
     {
-        private readonly TapetiConnectionParams result = new();
+        private readonly TapetiConnectionParams result = new TapetiAppSettingsConnectionParams();
 
         private readonly string connectionstring;
         private int pos = -1;

Tapeti/Tapeti.csproj

@@ -11,7 +11,7 @@
     <PackageLicenseExpression>Unlicense</PackageLicenseExpression>
     <PackageProjectUrl>https://github.com/MvRens/Tapeti</PackageProjectUrl>
     <PackageIcon>Tapeti.png</PackageIcon>
-    <LangVersion>latest</LangVersion>
+    <LangVersion>8</LangVersion>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">

Tapeti/TapetiConfig.cs

@@ -18,7 +18,7 @@ namespace Tapeti
     public class TapetiConfig : ITapetiConfigBuilder, ITapetiConfigBuilderAccess
     {
         private Config config;
-        private readonly List<IControllerBindingMiddleware> bindingMiddleware = new();
+        private readonly List<IControllerBindingMiddleware> bindingMiddleware = new List<IControllerBindingMiddleware>();
 
 
         /// <inheritdoc />
@@ -189,7 +189,7 @@ namespace Tapeti
         /// </summary>
         protected void RegisterDefaults()
         {
-            if (DependencyResolver is not IDependencyContainer container)
+            if (!(DependencyResolver is IDependencyContainer container))
                 return;
 
             if (ConsoleHelper.IsAvailable())
@@ -225,9 +225,9 @@ namespace Tapeti
         /// <inheritdoc />
         internal class Config : ITapetiConfig
         {
-            private readonly ConfigFeatures features = new();
-            private readonly ConfigMiddleware middleware = new();
-            private readonly ConfigBindings bindings = new();
+            private readonly ConfigFeatures features = new ConfigFeatures();
+            private readonly ConfigMiddleware middleware = new ConfigMiddleware();
+            private readonly ConfigBindings bindings = new ConfigBindings();
 
             public IDependencyResolver DependencyResolver { get; }
             public ITapetiConfigFeatues Features => features;
@@ -291,8 +291,8 @@ namespace Tapeti
 
         internal class ConfigMiddleware : ITapetiConfigMiddleware
         {
-            private readonly List<IMessageMiddleware> messageMiddleware = new();
-            private readonly List<IPublishMiddleware> publishMiddleware = new();
+            private readonly List<IMessageMiddleware> messageMiddleware = new List<IMessageMiddleware>();
+            private readonly List<IPublishMiddleware> publishMiddleware = new List<IPublishMiddleware>();
 
 
             public IReadOnlyList<IMessageMiddleware> Message => messageMiddleware;

Tapeti/TapetiConfigControllers.cs

@@ -79,7 +79,7 @@ namespace Tapeti
                 }
 
                 var methodQueueInfo = GetQueueInfo(method) ?? controllerQueueInfo;
-                if (methodQueueInfo is not { IsValid: true })
+                if (!(methodQueueInfo is { IsValid: true }))
                     throw new TopologyConfigurationException(
                         $"Method {method.Name} or controller {controller.Name} requires a queue attribute");
 

Tapeti/Tasks/SingleThreadTaskQueue.cs

@@ -12,10 +12,10 @@ namespace Tapeti.Tasks
     /// </summary>
     public class SingleThreadTaskQueue : IDisposable
     {
-        private readonly object previousTaskLock = new();
+        private readonly object previousTaskLock = new object();
         private Task previousTask = Task.CompletedTask;
 
-        private readonly Lazy<SingleThreadTaskScheduler> singleThreadScheduler = new();
+        private readonly Lazy<SingleThreadTaskScheduler> singleThreadScheduler = new Lazy<SingleThreadTaskScheduler>();
 
 
         /// <summary>
@@ -70,7 +70,7 @@ namespace Tapeti.Tasks
             public override int MaximumConcurrencyLevel => 1;
 
 
-            private readonly Queue<Task> scheduledTasks = new();
+            private readonly Queue<Task> scheduledTasks = new Queue<Task>();
             private bool disposed;