From 2ed506c010b41c41c01997c81df977831f0fa217 Mon Sep 17 00:00:00 2001
From: Jackson Schuster <36744439+jtschuster@users.noreply.github.com>
Date: Wed, 16 Aug 2023 11:53:02 -0700
Subject: [PATCH] [ComInterfaceGenerator] Add Caller Allocated Buffer
 collection marshaller and interface (#90107)

Co-authored-by: Jeremy Koritzinsky <jkoritzinsky@gmail.com>
---
 ...tatelessCollectionCallerAllocatedBuffer.cs | 140 ++++++++++++++++++
 .../IStatelessCollectionStatelessElement.cs   |   1 -
 2 files changed, 140 insertions(+), 1 deletion(-)
 create mode 100644 src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionCallerAllocatedBuffer.cs

diff --git a/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionCallerAllocatedBuffer.cs b/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionCallerAllocatedBuffer.cs
new file mode 100644
index 00000000000000..c13caee66fa472
--- /dev/null
+++ b/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionCallerAllocatedBuffer.cs
@@ -0,0 +1,140 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.Marshalling;
+
+namespace SharedTypes.ComInterfaces
+{
+    [GeneratedComInterface(), Guid("0A52B77C-E08B-4274-A1F4-1A2BF2C07E60")]
+    internal partial interface IStatelessCollectionCallerAllocatedBuffer
+    {
+        void Method(
+            [MarshalUsing(CountElementName = nameof(size))] StatelessCollectionCallerAllocatedBuffer<StatelessType> p,
+            int size);
+
+        void MethodIn(
+            [MarshalUsing(CountElementName = nameof(size))] in StatelessCollectionCallerAllocatedBuffer<StatelessType> pIn,
+            in int size);
+
+        void MethodRef(
+            [MarshalUsing(CountElementName = nameof(size))] ref StatelessCollectionCallerAllocatedBuffer<StatelessType> pRef,
+            int size);
+
+        void MethodOut(
+            [MarshalUsing(CountElementName = nameof(size))] out StatelessCollectionCallerAllocatedBuffer<StatelessType> pOut,
+            out int size);
+
+        [return: MarshalUsing(CountElementName = nameof(size))]
+        StatelessCollectionCallerAllocatedBuffer<StatelessType> Return(int size);
+
+        [PreserveSig]
+        [return: MarshalUsing(CountElementName = nameof(size))]
+        StatelessCollectionCallerAllocatedBuffer<StatelessType> ReturnPreserveSig(int size);
+    }
+
+    [NativeMarshalling(typeof(StatelessCollectionCallerAllocatedBufferMarshaller<,>))]
+    internal class StatelessCollectionCallerAllocatedBuffer<T>
+    {
+    }
+
+    internal struct StatelessCollectionCallerAllocatedBufferNative
+    {
+
+    }
+
+    [ContiguousCollectionMarshaller]
+    [CustomMarshaller(typeof(StatelessCollectionCallerAllocatedBuffer<>), MarshalMode.ManagedToUnmanagedIn, typeof(StatelessCollectionCallerAllocatedBufferMarshaller<,>.ManagedToUnmanaged))]
+    [CustomMarshaller(typeof(StatelessCollectionCallerAllocatedBuffer<>), MarshalMode.UnmanagedToManagedOut, typeof(StatelessCollectionCallerAllocatedBufferMarshaller<,>.ManagedToUnmanaged))]
+    [CustomMarshaller(typeof(StatelessCollectionCallerAllocatedBuffer<>), MarshalMode.ManagedToUnmanagedOut, typeof(StatelessCollectionCallerAllocatedBufferMarshaller<,>.UnmanagedToManaged))]
+    [CustomMarshaller(typeof(StatelessCollectionCallerAllocatedBuffer<>), MarshalMode.UnmanagedToManagedIn, typeof(StatelessCollectionCallerAllocatedBufferMarshaller<,>.UnmanagedToManaged))]
+    [CustomMarshaller(typeof(StatelessCollectionCallerAllocatedBuffer<>), MarshalMode.UnmanagedToManagedRef, typeof(StatelessCollectionCallerAllocatedBufferMarshaller<,>.Bidirectional))]
+    [CustomMarshaller(typeof(StatelessCollectionCallerAllocatedBuffer<>), MarshalMode.ManagedToUnmanagedRef, typeof(StatelessCollectionCallerAllocatedBufferMarshaller<,>.Bidirectional))]
+    internal static unsafe class StatelessCollectionCallerAllocatedBufferMarshaller<T, TUnmanagedElement> where TUnmanagedElement : unmanaged
+    {
+        internal static class Bidirectional
+        {
+            public static int BufferSize => throw new NotImplementedException();
+            public static StatelessCollectionCallerAllocatedBufferNative AllocateContainerForUnmanagedElements(StatelessCollectionCallerAllocatedBuffer<T> managed, Span<byte> buffer, out int numElements)
+            {
+                throw new NotImplementedException();
+            }
+
+            // Bidirectional requires non-buffer version of this method
+            public static StatelessCollectionCallerAllocatedBufferNative AllocateContainerForUnmanagedElements(StatelessCollectionCallerAllocatedBuffer<T> managed, out int numElements)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static StatelessCollectionCallerAllocatedBuffer<T> AllocateContainerForManagedElements(StatelessCollectionCallerAllocatedBufferNative unmanaged, int numElements)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static ReadOnlySpan<T> GetManagedValuesSource(StatelessCollectionCallerAllocatedBuffer<T> managed)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static Span<TUnmanagedElement> GetUnmanagedValuesDestination(StatelessCollectionCallerAllocatedBufferNative unmanaged, int numElements)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static ReadOnlySpan<TUnmanagedElement> GetUnmanagedValuesSource(StatelessCollectionCallerAllocatedBufferNative unmanaged, int numElements)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static Span<T> GetManagedValuesDestination(StatelessCollectionCallerAllocatedBuffer<T> managed)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static void Free(StatelessCollectionCallerAllocatedBufferNative unmanaged) { }
+        }
+
+        internal static class ManagedToUnmanaged
+        {
+            public static int BufferSize => throw new NotImplementedException();
+            public static StatelessCollectionCallerAllocatedBufferNative AllocateContainerForUnmanagedElements(StatelessCollectionCallerAllocatedBuffer<T> managed, Span<byte> buffer, out int numElements)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static ReadOnlySpan<T> GetManagedValuesSource(StatelessCollectionCallerAllocatedBuffer<T> managed)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static Span<TUnmanagedElement> GetUnmanagedValuesDestination(StatelessCollectionCallerAllocatedBufferNative unmanaged, int numElements)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static void Free(StatelessCollectionCallerAllocatedBufferNative unmanaged) => throw new NotImplementedException();
+        }
+
+        internal static class UnmanagedToManaged
+        {
+            public static StatelessCollectionCallerAllocatedBuffer<T> AllocateContainerForManagedElements(StatelessCollectionCallerAllocatedBufferNative unmanaged, int numElements)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static ReadOnlySpan<TUnmanagedElement> GetUnmanagedValuesSource(StatelessCollectionCallerAllocatedBufferNative unmanaged, int numElements)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static Span<T> GetManagedValuesDestination(StatelessCollectionCallerAllocatedBuffer<T> managed)
+            {
+                throw new NotImplementedException();
+            }
+
+            public static void Free(StatelessCollectionCallerAllocatedBufferNative unmanaged) => throw new NotImplementedException();
+
+        }
+    }
+}
diff --git a/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionStatelessElement.cs b/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionStatelessElement.cs
index b295a9adb919b7..68ad9f409b3b84 100644
--- a/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionStatelessElement.cs
+++ b/src/libraries/System.Runtime.InteropServices/tests/TestAssets/SharedTypes/ComInterfaces/IStatelessCollectionStatelessElement.cs
@@ -109,7 +109,6 @@ public static Span<TUnmanagedElement> GetUnmanagedValuesDestination(NativeCollec
             }
 
             public static void Free(NativeCollection<T> unmanaged) => throw new NotImplementedException();
-
         }
 
         internal static class UnmanagedToManaged