Prepare for .NET 9 switches

Author: sakno

src/DotNext/Buffers/SpanOwner.cs

@@ -137,7 +137,7 @@ static unsafe Span<T> Allocate(int length)
     private static bool IsNaturalAlignment => Intrinsics.AlignOf<T>() <= nuint.Size;
 
     private static bool UseNativeAllocation
-        => !LibrarySettings.DisableNativeAllocation && !RuntimeHelpers.IsReferenceOrContainsReferences<T>();
+        => LibrarySettings.UseNativeAllocation && !RuntimeHelpers.IsReferenceOrContainsReferences<T>();
 
     /// <summary>
     /// Gets the rented memory.

src/DotNext/LibrarySettings.cs

@@ -1,7 +1,12 @@
+using System.Diagnostics.CodeAnalysis;
+
 namespace DotNext;
 
 internal static class LibrarySettings
 {
+    private const string UseNativeAllocationFeature = "DotNext.Buffers.NativeAllocation";
+    private const string UseRandomStringInternalBufferCleanupFeature = "DotNext.Security.RandomStringInternalBufferCleanup";
+    
     internal static int StackallocThreshold
     {
         get
@@ -19,32 +24,15 @@ internal static int StackallocThreshold
             return result > minimumValue ? result : defaultValue;
         }
     }
+    
+    private static bool IsSupported([ConstantExpected] string featureName)
+        => !AppContext.TryGetSwitch(featureName, out var result) || result;
 
-    internal static bool DisableRandomStringInternalBufferCleanup
-    {
-        get
-        {
-            const string switchName = "DotNext.Security.DisableRandomStringInternalBufferCleanup";
-            const bool defaultValue = false;
-
-            if (!AppContext.TryGetSwitch(switchName, out var result))
-                result = defaultValue;
-
-            return result;
-        }
-    }
+    // TODO: [FeatureSwitchDefinition(UseRandomStringInternalBufferCleanupFeature)]
+    internal static bool UseRandomStringInternalBufferCleanup
+        => IsSupported(UseRandomStringInternalBufferCleanupFeature);
 
-    internal static bool DisableNativeAllocation
-    {
-        get
-        {
-            const string switchName = "DotNext.Buffers.DisableNativeAllocation";
-            const bool defaultValue = false;
-
-            if (!AppContext.TryGetSwitch(switchName, out var result))
-                result = defaultValue;
-
-            return result;
-        }
-    }
+    // TODO: [FeatureSwitchDefinition(EnableNativeAllocationFeature)]
+    internal static bool UseNativeAllocation
+        => IsSupported(UseNativeAllocationFeature);
 }

src/DotNext/RandomExtensions.cs

@@ -19,8 +19,6 @@ public static class RandomExtensions
     /// </summary>
     internal static readonly int BitwiseHashSalt = Random.Shared.Next();
 
-    private static readonly bool CleanupInternalBuffer = !LibrarySettings.DisableRandomStringInternalBufferCleanup;
-
     private interface IRandomBytesSource
     {
         void GetBytes(Span<byte> bytes);
@@ -141,7 +139,7 @@ ref MemoryMarshal.GetReference(allowedInput),
             new CachedRandomNumberGenerator<TRandom>(random, randomVectorBuffer.Span).Randomize(allowedInput, buffer);
         }
 
-        if (CleanupInternalBuffer)
+        if (LibrarySettings.UseRandomStringInternalBufferCleanup)
             randomVectorBuffer.Span.Clear();
 
         static void FastPath(ref uint randomVectorPtr, ref T inputPtr, uint moduloOperand, Span<T> output)