Add inline array marshaller sample to our custom marshalling sample.

core/interop/source-generation/custom-marshalling/src/custommarshalling/ErrorBuffer.cs

@@ -0,0 +1,33 @@
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.Marshalling;
+
+namespace CustomMarshalling
+{
+    [NativeMarshalling(typeof(ErrorBufferMarshaller))]
+    [InlineArray(4)]
+    public struct ErrorBuffer
+    {
+        private ErrorData _data;
+    }
+
+    [CustomMarshaller(typeof(ErrorBuffer), MarshalMode.ManagedToUnmanagedIn, typeof(ErrorBufferMarshaller))]
+    public static class ErrorBufferMarshaller
+    {
+        [InlineArray(4)]
+        public struct ErrorBufferUnmanaged
+        {
+            private ErrorDataMarshaller.ErrorDataUnmanaged _data;
+        }
+
+        public static ErrorBufferUnmanaged ConvertToUnmanaged(ErrorBuffer managed)
+        {
+            ErrorBufferUnmanaged unmanaged = new();
+            for (int i = 0; i < 4; i++)
+            {
+                unmanaged[i] = ErrorDataMarshaller.ConvertToUnmanaged(managed[i]);
+            }
+            return unmanaged;
+        }
+    }
+}

core/interop/source-generation/custom-marshalling/src/custommarshalling/NativeLib.cs

@@ -28,5 +28,8 @@ internal partial class NativeLib
         [LibraryImport(LibName)]
         [return: MarshalUsing(CountElementName = "len")]
         internal static partial ErrorData[] GetErrors(int[] codes, int len);
+
+        [LibraryImport(LibName)]
+        internal static partial void GetErrorCodes(ErrorBuffer buffer, int[] codes);
     }
 }

core/interop/source-generation/custom-marshalling/src/custommarshalling/Program.cs

@@ -79,11 +79,20 @@ static void MarshalErrorData()
 
     // Marshals ErrorData using ErrorDataMarshaller
     Console.WriteLine($"--- {nameof(NativeLib.GetErrors)}: uses {nameof(ErrorDataMarshaller)}.{nameof(ErrorDataMarshaller.Out)}");
-    int[] codes = new int[] { -3, 2, 5 };
+    int[] codes = new int[] { -3, 2, 5, 12 };
     ErrorData[] errors = NativeLib.GetErrors(codes, codes.Length);
     foreach (ErrorData error in errors)
     {
         error.Print();
         Console.WriteLine();
     }
+
+    ErrorBuffer errorBuffer = new();
+    errors.AsSpan().CopyTo(errorBuffer);
+    int[] retrievedCodes = new int[4];
+    NativeLib.GetErrorCodes(errorBuffer, retrievedCodes);
+    foreach (int code in retrievedCodes)
+    {
+        Console.WriteLine($"Code from error data: {code}");
+    }
 }

core/interop/source-generation/custom-marshalling/src/custommarshalling/custommarshalling.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <RootNamespace>CustomMarshalling</RootNamespace>

core/interop/source-generation/custom-marshalling/src/nativelib/nativelib.cpp

@@ -108,3 +108,14 @@ extern "C" DLL_EXPORT error_data* STDMETHODCALLTYPE GetErrors(int* codes, int le
 
     return ret;
 }
+
+struct error_data_buffer
+{
+    error_data data[4];
+};
+
+extern "C" DLL_EXPORT void STDMETHODCALLTYPE GetErrorCodes(error_data_buffer errors, int* codes)
+{
+    for (int i = 0; i < 4; ++i)
+        codes[i] = errors.data[i].code;
+}