Prevent diagnostics on .NET SDK 8.0.100 (#2049)

Address collection expression diagnostics

In most cases, we now just use the new (C# 12.0) collection expression syntax. However, we've disabled IDE0305 because it makes suggestions that aren't an obvious improvement. It wants to rewrite use of ToArray() to be a collection expression. E.g. something.ToArray() would become [.. something]. Perhaps that will seem natural once we've all got used to spreads in collection expressions, but to me (idg10) today that looks odd.

Add comment explaining why we've disable IDE0290

Make UWP test runner use the same warning settings as everything else, except for CS0618, which a large number of tests appear to depend on.

Author: idg10

Rx.NET/Source/Directory.build.props

@@ -61,7 +61,7 @@
     <EnableNETAnalyzers>true</EnableNETAnalyzers>
 
     <!--
-    Disable diagnostics:
+    Disabled diagnostics:
     CA1001 - types holding disposable fields should implement IDisposable. See next item.
     CA2213 - IDisposable types should Dispose any IDisposable fields. This rule finds over 600
                 examples! These are all in subtle multithreaded or async code. Some of them appear
@@ -74,9 +74,21 @@
 
     IDE0056 - Use of index/range syntax - relevant types not available on all targets, so we can't
     IDE0057     do this.
+
+    IDE0290 - Primary ctors. This diagnostic suggests them in a lot of places where we don't want
+                them. E.g., in most types with multiple constructors I find I prefer not to have
+                a primary ctor. Since this is all or nothing, we turn it off.
+    IDE0305 - Suggests Collection expressions in place of .ToArray. E.g, wants to change this:
+                  _readyList.ToArray()
+              to this:
+                  [.. readyList]
+              This won't improve performance as far as we know (sometimes a reason for using that
+              syntax), and it's not obviously an improvement in readability.
+
+    CA1510 - use ArgumentNullException.ThrowIf (not available on all targets)
+    CA1513 - use ObjectDisposedException.ThrowIf (not available on all targets)
     -->
-    <!-- Get diagnostics back to the level that the .NET 5.0 SDK had for now. Fix these properly before release. -->
-    <NoWarn>$(NoWarn);CA1001;CA2213;IDE0056;IDE0057</NoWarn>
+    <NoWarn>$(NoWarn);CA1001;CA2213;CA1510;CA1513;IDE0056;IDE0057;IDE0290;IDE0305</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>

Rx.NET/Source/src/Microsoft.Reactive.Testing/ColdObservable.cs

@@ -13,7 +13,7 @@ internal class ColdObservable<T> : ITestableObservable<T>
     {
         private readonly TestScheduler _scheduler;
         private readonly Recorded<Notification<T>>[] _messages;
-        private readonly List<Subscription> _subscriptions = new();
+        private readonly List<Subscription> _subscriptions = [];
 
         public ColdObservable(TestScheduler scheduler, params Recorded<Notification<T>>[] messages)
         {

Rx.NET/Source/src/Microsoft.Reactive.Testing/HotObservable.cs

@@ -12,8 +12,8 @@ namespace Microsoft.Reactive.Testing
     internal class HotObservable<T> : ITestableObservable<T>
     {
         private readonly TestScheduler _scheduler;
-        private readonly List<IObserver<T>> _observers = new();
-        private readonly List<Subscription> _subscriptions = new();
+        private readonly List<IObserver<T>> _observers = [];
+        private readonly List<Subscription> _subscriptions = [];
         private readonly Recorded<Notification<T>>[] _messages;
 
         public HotObservable(TestScheduler scheduler, params Recorded<Notification<T>>[] messages)

Rx.NET/Source/src/Microsoft.Reactive.Testing/MockObserver.cs

@@ -11,12 +11,11 @@ namespace Microsoft.Reactive.Testing
     internal class MockObserver<T> : ITestableObserver<T>
     {
         private readonly TestScheduler _scheduler;
-        private readonly List<Recorded<Notification<T>>> _messages;
+        private readonly List<Recorded<Notification<T>>> _messages = [];
 
         public MockObserver(TestScheduler scheduler)
         {
             _scheduler = scheduler ?? throw new ArgumentNullException(nameof(scheduler));
-            _messages = new List<Recorded<Notification<T>>>();
         }
 
         public void OnNext(T value)

Rx.NET/Source/src/System.Reactive/Concurrency/LocalScheduler.TimerQueue.cs

@@ -55,7 +55,7 @@ public partial class LocalScheduler
         /// Set of disposable handles to all of the current short term work Schedule calls,
         /// allowing those to be cancelled upon a system clock change.
         /// </summary>
-        private readonly HashSet<IDisposable> _shortTermWork = new();
+        private readonly HashSet<IDisposable> _shortTermWork = [];
 
         /// <summary>
         /// Threshold where an item is considered to be short term work or gets moved from

Rx.NET/Source/src/System.Reactive/Concurrency/Scheduler.Recursive.cs

@@ -175,12 +175,11 @@ private abstract class InvokeRecBaseState : IDisposable
         {
             protected readonly IScheduler Scheduler;
 
-            protected readonly CompositeDisposable Group;
+            protected readonly CompositeDisposable Group = [];
 
             protected InvokeRecBaseState(IScheduler scheduler)
             {
                 Scheduler = scheduler;
-                Group = new CompositeDisposable();
             }
 
             public void Dispose()

Rx.NET/Source/src/System.Reactive/Concurrency/Scheduler.Services.cs

@@ -10,12 +10,13 @@ namespace System.Reactive.Concurrency
     //
     public static partial class Scheduler
     {
-        internal static Type[] Optimizations = {
+        internal static Type[] Optimizations =
+        [
             typeof(ISchedulerLongRunning),
             typeof(IStopwatchProvider),
             typeof(ISchedulerPeriodic)
             /* update this list if new interface-based optimizations are added */
-        };
+        ];
 
         /// <summary>
         /// Returns the <see cref="ISchedulerLongRunning"/> implementation of the specified scheduler, or <c>null</c> if no such implementation is available.

Rx.NET/Source/src/System.Reactive/Concurrency/SchedulerWrapper.cs

@@ -9,12 +9,16 @@ namespace System.Reactive.Concurrency
     internal abstract class SchedulerWrapper : IScheduler, IServiceProvider
     {
         protected readonly IScheduler _scheduler;
-        private readonly ConditionalWeakTable<IScheduler, IScheduler> _cache;
+        private readonly ConditionalWeakTable<IScheduler, IScheduler> _cache =
+#if NET472_OR_GREATER || NETSTANDARD2_0_OR_GREATER
+            new();
+#else
+            [];
+#endif
 
         protected SchedulerWrapper(IScheduler scheduler)
         {
             _scheduler = scheduler;
-            _cache = new ConditionalWeakTable<IScheduler, IScheduler>();
         }
 
         protected SchedulerWrapper(IScheduler scheduler, ConditionalWeakTable<IScheduler, IScheduler> cache)

Rx.NET/Source/src/System.Reactive/Diagnostics/CodeAnalysis/NullableAttributes.cs

@@ -96,7 +96,7 @@ internal sealed class MemberNotNullAttribute : Attribute
         /// The field or property member that is promised to be not-null.
         /// </param>
 #pragma warning disable CA1019 // Define accessors for attribute arguments - this needs to be identical to the real type
-        public MemberNotNullAttribute(string member) => Members = new[] { member };
+        public MemberNotNullAttribute(string member) => Members = [member];
 #pragma warning restore CA1019
 
         /// <summary>Initializes the attribute with the list of field and property members.</summary>
@@ -125,7 +125,7 @@ public MemberNotNullWhenAttribute(bool returnValue, string member)
 #pragma warning restore CA1019
         {
             ReturnValue = returnValue;
-            Members = new[] { member };
+            Members = [member];
         }
 
         /// <summary>Initializes the attribute with the specified return value condition and list of field and property members.</summary>

Rx.NET/Source/src/System.Reactive/Disposables/CompositeDisposable.cs

@@ -29,7 +29,7 @@ public sealed class CompositeDisposable : ICollection<IDisposable>, ICancelable
         /// </summary>
         public CompositeDisposable()
         {
-            _disposables = new List<IDisposable?>();
+            _disposables = [];
         }
 
         /// <summary>
@@ -387,7 +387,7 @@ public IEnumerator<IDisposable> GetEnumerator()
         /// method to avoid allocation on disposed or empty composites.
         /// </summary>
         private static readonly CompositeEnumerator EmptyEnumerator =
-            new(Array.Empty<IDisposable?>());
+            new([]);
 
         /// <summary>
         /// An enumerator for an array of disposables.