Add the struct marshalling attributes to Ancillary.Interop and add an analyzer that validates manual usage.

DllImportGenerator/Ancillary.Interop/GeneratedMarshallingAttribute.cs

@@ -0,0 +1,36 @@
+#nullable enable
+
+namespace System.Runtime.InteropServices
+{
+    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct)]
+    class GeneratedMarshallingAttribute : Attribute
+    {
+    }
+
+    [AttributeUsage(AttributeTargets.Struct)]
+    public class BlittableTypeAttribute : Attribute
+    {
+    }
+
+    [AttributeUsage(AttributeTargets.Struct | AttributeTargets.Class)]
+    public class NativeMarshallingAttribute : Attribute
+    {
+        public NativeMarshallingAttribute(Type nativeType)
+        {
+            NativeType = nativeType;
+        }
+
+        public Type NativeType { get; }
+    }
+
+    [AttributeUsage(AttributeTargets.Parameter | AttributeTargets.ReturnValue | AttributeTargets.Field)]
+    public class MarshalUsingAttribute : Attribute
+    {
+        public MarshalUsingAttribute(Type nativeType)
+        {
+            NativeType = nativeType;
+        }
+
+        public Type NativeType { get; }
+    }
+}

DllImportGenerator/DllImportGenerator.Test/CompileFails.cs

@@ -1,5 +1,6 @@
 using Microsoft.CodeAnalysis;
 using System.Collections.Generic;
+using System.Threading.Tasks;
 using Xunit;
 
 namespace DllImportGenerator.Test
@@ -13,9 +14,9 @@ public static IEnumerable<object[]> CodeSnippetsToCompile()
 
         [Theory]
         [MemberData(nameof(CodeSnippetsToCompile))]
-        public void ValidateSnippets(string source, int failCount)
+        public async Task ValidateSnippets(string source, int failCount)
         {
-            Compilation comp = TestUtils.CreateCompilation(source);
+            Compilation comp = await TestUtils.CreateCompilation(source);
             TestUtils.AssertPreSourceGeneratorCompilation(comp);
 
             var newComp = TestUtils.RunGenerators(comp, out var generatorDiags, new Microsoft.Interop.DllImportGenerator());

DllImportGenerator/DllImportGenerator.Test/Compiles.cs

@@ -1,5 +1,6 @@
 using Microsoft.CodeAnalysis;
 using System.Collections.Generic;
+using System.Threading.Tasks;
 using Xunit;
 
 namespace DllImportGenerator.Test
@@ -23,9 +24,9 @@ public static IEnumerable<object[]> CodeSnippetsToCompile()
 
         [Theory]
         [MemberData(nameof(CodeSnippetsToCompile))]
-        public void ValidateSnippets(string source)
+        public async Task ValidateSnippets(string source)
         {
-            Compilation comp = TestUtils.CreateCompilation(source);
+            Compilation comp = await TestUtils.CreateCompilation(source);
             TestUtils.AssertPreSourceGeneratorCompilation(comp);
 
             var newComp = TestUtils.RunGenerators(comp, out var generatorDiags, new Microsoft.Interop.DllImportGenerator());

DllImportGenerator/DllImportGenerator.Test/DllImportGenerator.Test.csproj

@@ -9,6 +9,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="3.7.0-3.final" PrivateAssets="all" />
     <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.0-beta1.final" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Analyzer.Testing.XUnit" Version="1.0.1-beta1.20418.1" PrivateAssets="all" />
     <PackageReference Include="Microsoft.Net.Compilers.Toolset" Version="3.7.0-3.final">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
@@ -29,5 +30,8 @@
     <ProjectReference Include="..\Ancillary.Interop\Ancillary.Interop.csproj" />
     <ProjectReference Include="..\DllImportGenerator\DllImportGenerator.csproj" />
   </ItemGroup>
-
+
+  <PropertyGroup>
+    <RestoreAdditionalProjectSources>https://dotnet.myget.org/F/roslyn-analyzers/api/v3/index.json ;$(RestoreAdditionalProjectSources)</RestoreAdditionalProjectSources>
+  </PropertyGroup>
 </Project>