Mark DirectSoundOut as Windows-only

Author: ds5678

NAudio.Core/NAudio.Core.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <LangVersion>Latest</LangVersion>
     <Authors>Mark Heath</Authors>
     <Version>2.2.0</Version>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
@@ -15,6 +16,7 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>
     <PackageIcon>naudio-icon.png</PackageIcon>
+    <PolySharpIncludeRuntimeSupportedAttributes>true</PolySharpIncludeRuntimeSupportedAttributes>
   </PropertyGroup>
 
   <ItemGroup>
@@ -24,5 +26,12 @@
     </None>
   </ItemGroup>
 
+  <ItemGroup>
+    <PackageReference Include="PolySharp" Version="1.13.2">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+
 
 </Project>

NAudio.Core/Wave/WaveOutputs/DirectSoundOut.cs

@@ -12,6 +12,7 @@ namespace NAudio.Wave
     /// Contact author: Alexandre Mutel - alexandre_mutel at yahoo.fr
     /// Modified by: Graham "Gee" Plumb
     /// </summary>
+    [System.Runtime.Versioning.SupportedOSPlatform("windows")]
     public class DirectSoundOut : IWavePlayer
     {
         /// <summary>
@@ -69,7 +70,7 @@ private static bool EnumCallback(IntPtr lpGuid, IntPtr lpcstrDescription, IntPtr
                 device.Guid = new Guid(guidBytes);
             }
             device.Description =  Marshal.PtrToStringAnsi(lpcstrDescription);
-            if (lpcstrModule != null)
+            if (lpcstrModule != IntPtr.Zero)
             {
                 device.ModuleName = Marshal.PtrToStringAnsi(lpcstrModule);
             }