[mono][aot] Emit marhsalling exception when dealing with MONO_MARSHAL_CONV_OBJECT_IUNKNOWN (#105156)

This change prevents the aot compiler from erroring out when dealing with COM types that were not marked with MarshalAs attributes. In most scenarios that we support, we want to allow pinvokes to aot compile as in cases like anything COM interop, will end up erroring out if you try to use it.

Fixes #104463

Author: steveisok

src/mono/mono/metadata/marshal-shared.c

@@ -1225,6 +1225,11 @@ mono_marshal_shared_emit_object_to_ptr_conv (MonoMethodBuilder *mb, MonoType *ty
 		mono_mb_emit_byte (mb, CEE_STIND_I);
 		break;
 	}
+	case MONO_MARSHAL_CONV_OBJECT_IUNKNOWN: {
+		char *msg = g_strdup_printf ("Marshaling not supported for COM type MONO_MARSHAL_CONV_OBJECT_IUNKNOWN.");
+		mono_marshal_shared_mb_emit_exception_marshal_directive (mb, msg);
+		break;
+	}
 
 	default: {
 		g_error ("marshalling conversion %d not implemented", conv);

src/mono/wasm/Wasm.Build.Tests/PInvokeTableGeneratorTests.cs

@@ -719,6 +719,44 @@ void GenerateSourceFiles(string outputPath, int baseArg)
             return (buildArgs, output);
         }
 
+        private void EnsureComInteropCompiles(BuildArgs buildArgs, RunHost host, string id)
+        {
+            string programText = @"
+                using System;
+                using System.Runtime.CompilerServices;
+                using System.Runtime.InteropServices;
+                using System.Runtime.InteropServices.ComTypes;
+
+                public class Test
+                {
+                    public static int Main(string[] args)
+                    {
+                        var s = new STGMEDIUM();
+                        ReleaseStgMedium(ref s);
+                        return 42;
+                    }
+
+                    [DllImport(""ole32.dll"")]
+                    internal static extern void ReleaseStgMedium(ref STGMEDIUM medium);
+                }
+
+            ";
+
+            buildArgs = ExpandBuildArgs(buildArgs);
+
+            (string libraryDir, string output) = BuildProject(buildArgs,
+                                        id: id,
+                                        new BuildProjectOptions(
+                                            InitProject: () =>
+                                            {
+                                                File.WriteAllText(Path.Combine(_projectDir!, "Program.cs"), programText);
+                                            },
+                                            Publish: buildArgs.AOT,
+                                            DotnetWasmFromRuntimePack: true));
+
+            Assert.Contains("Generated app bundle at " + libraryDir, output);
+        }
+
         private void EnsureWasmAbiRulesAreFollowed(BuildArgs buildArgs, RunHost host, string id)
         {
             string programText = @"
@@ -885,6 +923,11 @@ public void EnsureWasmAbiRulesAreFollowedInAOT(BuildArgs buildArgs, RunHost host
         public void EnsureWasmAbiRulesAreFollowedInInterpreter(BuildArgs buildArgs, RunHost host, string id) =>
             EnsureWasmAbiRulesAreFollowed(buildArgs, host, id);
 
+        [Theory]
+        [BuildAndRun(host: RunHost.Chrome, aot: true)]
+        public void EnsureComInteropCompilesInAOT(BuildArgs buildArgs, RunHost host, string id) =>
+            EnsureComInteropCompiles(buildArgs, host, id);
+
         [Theory]
         [BuildAndRun(host: RunHost.Chrome, aot: false)]
         public void UCOWithSpecialCharacters(BuildArgs buildArgs, RunHost host, string id)

src/mono/wasm/Wasm.Build.Tests/README.md

@@ -14,7 +14,7 @@ being generated.
 
 - Running:
 
-Linux/macOS: `$ make -C src/mono/wasm run-build-tests`
+Linux/macOS: `$ make -C src/mono/(browser|wasi) run-build-tests`
 Windows: `.\dotnet.cmd build .\src\mono\wasm\Wasm.Build.Tests\Wasm.Build.Tests.csproj -c Release -t:Test -p:TargetOS=browser -p:TargetArchitecture=wasm`
 
 - Specific tests can be run via `XUnitClassName`, and `XUnitMethodName`