Add custom exception handlers to generated COM wrappers

src/libraries/System.Runtime.InteropServices/gen/ComInterfaceGenerator/ComInterfaceGenerator.cs

@@ -106,7 +106,7 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
                     return new ComMethodContext(
                         data.Method,
                         data.OwningInterface,
-                        CalculateStubInformation(data.Method.MethodInfo.Syntax, symbolMap[data.Method.MethodInfo], data.Method.Index, env, data.OwningInterface.Info.Type, ct));
+                        CalculateStubInformation(data.Method.MethodInfo.Syntax, symbolMap[data.Method.MethodInfo], data.Method.Index, env, data.OwningInterface.Info.Type, data.OwningInterface.Info.ExceptionToUnmanagedMarshallerQualifiedName, ct));
                 }).WithTrackingName(StepNames.CalculateStubInformation);
 
             var interfaceAndMethodsContexts = comMethodContexts
@@ -245,7 +245,7 @@ private static bool IsHResultLikeType(ManagedTypeInfo type)
                 || typeName.Equals("hresult", StringComparison.OrdinalIgnoreCase);
         }
 
-        private static IncrementalMethodStubGenerationContext CalculateStubInformation(MethodDeclarationSyntax syntax, IMethodSymbol symbol, int index, StubEnvironment environment, ManagedTypeInfo owningInterface, CancellationToken ct)
+        private static IncrementalMethodStubGenerationContext CalculateStubInformation(MethodDeclarationSyntax syntax, IMethodSymbol symbol, int index, StubEnvironment environment, ManagedTypeInfo owningInterface, string? exceptionToUnmanagedMarshallerQualifiedName, CancellationToken ct)
         {
             ct.ThrowIfCancellationRequested();
             INamedTypeSymbol? lcidConversionAttrType = environment.LcidConversionAttrType;
@@ -396,7 +396,7 @@ private static IncrementalMethodStubGenerationContext CalculateStubInformation(M
                 locations,
                 callConv.ToSequenceEqualImmutableArray(SyntaxEquivalentComparer.Instance),
                 virtualMethodIndexData,
-                new ComExceptionMarshalling(),
+                new ComExceptionMarshalling(exceptionToUnmanagedMarshallerQualifiedName),
                 environment.EnvironmentFlags,
                 owningInterface,
                 declaringType,

src/libraries/System.Runtime.InteropServices/gen/ComInterfaceGenerator/ComInterfaceInfo.cs

@@ -29,6 +29,7 @@ internal sealed record ComInterfaceInfo
         public ComInterfaceOptions Options { get; init; }
         public Location DiagnosticLocation { get; init; }
         public bool IsExternallyDefined { get; init; }
+        public string? ExceptionToUnmanagedMarshallerQualifiedName { get; init; }
 
         private ComInterfaceInfo(
             ManagedTypeInfo type,
@@ -39,7 +40,8 @@ private ComInterfaceInfo(
             ContainingSyntax containingSyntax,
             Guid interfaceId,
             ComInterfaceOptions options,
-            Location diagnosticLocation)
+            Location diagnosticLocation,
+            string? exceptionToUnmanagedMarshallerFullyQualifiedName)
         {
             Type = type;
             ThisInterfaceKey = thisInterfaceKey;
@@ -50,6 +52,7 @@ private ComInterfaceInfo(
             InterfaceId = interfaceId;
             Options = options;
             DiagnosticLocation = diagnosticLocation;
+            ExceptionToUnmanagedMarshallerQualifiedName = exceptionToUnmanagedMarshallerFullyQualifiedName;
         }
 
         public static DiagnosticOrInterfaceInfo From(INamedTypeSymbol symbol, InterfaceDeclarationSyntax syntax, StubEnvironment env, CancellationToken _)
@@ -94,6 +97,9 @@ public static DiagnosticOrInterfaceInfo From(INamedTypeSymbol symbol, InterfaceD
             if (!OptionsAreValid(symbol, syntax, interfaceAttributeData, baseAttributeData, out DiagnosticInfo? optionsDiagnostic))
                 return DiagnosticOrInterfaceInfo.From(optionsDiagnostic);
 
+            if (!ExceptionToUnmanagedMarshallerIsValid(syntax, interfaceAttributeData, out string? exceptionToUnmanagedMarshallerFullyQualifiedName, out DiagnosticInfo? exceptionToUnmanagedMarshallerDiagnostic))
+                return DiagnosticOrInterfaceInfo.From(exceptionToUnmanagedMarshallerDiagnostic);
+
             InterfaceInfo info = (
                 new ComInterfaceInfo(
                     ManagedTypeInfo.CreateTypeInfoForTypeSymbol(symbol),
@@ -104,7 +110,8 @@ public static DiagnosticOrInterfaceInfo From(INamedTypeSymbol symbol, InterfaceD
                     new ContainingSyntax(syntax.Modifiers, syntax.Kind(), syntax.Identifier, syntax.TypeParameterList),
                     guid ?? Guid.Empty,
                     interfaceAttributeData.Options,
-                    syntax.Identifier.GetLocation()),
+                    syntax.Identifier.GetLocation(),
+                    exceptionToUnmanagedMarshallerFullyQualifiedName),
                 symbol);
 
             // Now that we've validated all of our requirements, we will check for some non-blocking scenarios
@@ -138,6 +145,11 @@ public static DiagnosticOrInterfaceInfo From(INamedTypeSymbol symbol, InterfaceD
             return DiagnosticOrInterfaceInfo.From(info);
         }
 
+        internal static readonly SymbolDisplayFormat QualifiedNameOnlyFormat =
+            new SymbolDisplayFormat(
+                globalNamespaceStyle: SymbolDisplayGlobalNamespaceStyle.Omitted,
+                typeQualificationStyle: SymbolDisplayTypeQualificationStyle.NameAndContainingTypesAndNamespaces);
+
         public static ImmutableArray<InterfaceInfo> CreateInterfaceInfoForBaseInterfacesInOtherCompilations(
             INamedTypeSymbol symbol)
         {
@@ -153,6 +165,7 @@ public static ImmutableArray<InterfaceInfo> CreateInterfaceInfoForBaseInterfaces
                 var thisSymbol = baseSymbol;
                 TryGetBaseComInterface(thisSymbol, null, out baseSymbol, out _);
                 var interfaceAttributeData = GeneratedComInterfaceCompilationData.GetAttributeDataFromInterfaceSymbol(thisSymbol);
+                string? exceptionToUnmanagedMarshallerQualifiedName = interfaceAttributeData.ExceptionToUnmanagedMarshaller?.ToDisplayString(QualifiedNameOnlyFormat);
                 builder.Add((
                     new ComInterfaceInfo(
                         ManagedTypeInfo.CreateTypeInfoForTypeSymbol(thisSymbol),
@@ -163,7 +176,8 @@ public static ImmutableArray<InterfaceInfo> CreateInterfaceInfoForBaseInterfaces
                         default,
                         Guid.Empty,
                         interfaceAttributeData.Options,
-                        Location.None)
+                        Location.None,
+                        exceptionToUnmanagedMarshallerQualifiedName)
                     {
                         IsExternallyDefined = true
                     },
@@ -285,6 +299,38 @@ private static bool OptionsAreValid(
             return true;
         }
 
+        private static bool ExceptionToUnmanagedMarshallerIsValid(
+            InterfaceDeclarationSyntax syntax,
+            GeneratedComInterfaceCompilationData attrSymbolInfo,
+            out string? exceptionToUnmanagedMarshallerFullyQualifiedName,
+            [NotNullWhen(false)] out DiagnosticInfo? exceptionToUnmanagedMarshallerDiagnostic)
+        {
+            GeneratedComInterfaceData attrInfo = GeneratedComInterfaceData.From(attrSymbolInfo);
+            if (attrSymbolInfo.ExceptionToUnmanagedMarshaller is INamedTypeSymbol exceptionToUnmanagedMarshallerType)
+            {
+                if (!exceptionToUnmanagedMarshallerType.IsAccessibleFromFileScopedClass(out var details))
+                {
+                    exceptionToUnmanagedMarshallerDiagnostic = DiagnosticInfo.Create(
+                        GeneratorDiagnostics.ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode,
+                        syntax.Identifier.GetLocation(),
+                        attrInfo.ExceptionToUnmanagedMarshaller.FullTypeName.Replace(TypeNames.GlobalAlias, ""),
+                        details);
+                    exceptionToUnmanagedMarshallerFullyQualifiedName = null;
+                    return false;
+                }
+                else
+                {
+                    exceptionToUnmanagedMarshallerFullyQualifiedName = exceptionToUnmanagedMarshallerType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);
+                }
+            }
+            else
+            {
+                exceptionToUnmanagedMarshallerFullyQualifiedName = null;
+            }
+            exceptionToUnmanagedMarshallerDiagnostic = null;
+            return true;
+        }
+
         /// <summary>
         /// Returns true if there is 0 or 1 base Com interfaces (i.e. the inheritance is valid), and returns false when there are 2 or more base Com interfaces and sets <paramref name="diagnostic"/>.
         /// </summary>

src/libraries/System.Runtime.InteropServices/gen/ComInterfaceGenerator/GeneratedComInterfaceAttributeData.cs

@@ -15,6 +15,7 @@ namespace Microsoft.Interop
     internal sealed record GeneratedComInterfaceData : InteropAttributeData
     {
         public ComInterfaceOptions Options { get; init; }
+        public ManagedTypeInfo? ExceptionToUnmanagedMarshaller { get; init; }
         public static GeneratedComInterfaceData From(GeneratedComInterfaceCompilationData generatedComInterfaceAttr)
             => new GeneratedComInterfaceData() with
             {
@@ -24,7 +25,10 @@ public static GeneratedComInterfaceData From(GeneratedComInterfaceCompilationDat
                 StringMarshallingCustomType = generatedComInterfaceAttr.StringMarshallingCustomType is not null
                     ? ManagedTypeInfo.CreateTypeInfoForTypeSymbol(generatedComInterfaceAttr.StringMarshallingCustomType)
                     : null,
-                Options = generatedComInterfaceAttr.Options
+                Options = generatedComInterfaceAttr.Options,
+                ExceptionToUnmanagedMarshaller = generatedComInterfaceAttr.ExceptionToUnmanagedMarshaller is not null
+                    ? ManagedTypeInfo.CreateTypeInfoForTypeSymbol(generatedComInterfaceAttr.ExceptionToUnmanagedMarshaller)
+                    : null,
             };
     }
 
@@ -35,6 +39,7 @@ public static GeneratedComInterfaceData From(GeneratedComInterfaceCompilationDat
     internal sealed record GeneratedComInterfaceCompilationData : InteropAttributeCompilationData
     {
         public ComInterfaceOptions Options { get; init; } = ComInterfaceOptions.ManagedObjectWrapper | ComInterfaceOptions.ComObjectWrapper;
+        public INamedTypeSymbol? ExceptionToUnmanagedMarshaller { get; init; }
 
         public static bool TryGetGeneratedComInterfaceAttributeFromInterface(INamedTypeSymbol interfaceSymbol, [NotNullWhen(true)] out AttributeData? generatedComInterfaceAttribute)
         {
@@ -70,6 +75,17 @@ public static GeneratedComInterfaceCompilationData GetDataFromAttribute(Attribut
                     Options = (ComInterfaceOptions)options.Value
                 };
             }
+            if (args.TryGetValue(nameof(ExceptionToUnmanagedMarshaller), out TypedConstant exceptionToUnmanagedMarshaller))
+            {
+                if (exceptionToUnmanagedMarshaller.Value is not INamedTypeSymbol)
+                {
+                    return null;
+                }
+                generatedComInterfaceAttributeData = generatedComInterfaceAttributeData with
+                {
+                    ExceptionToUnmanagedMarshaller = (INamedTypeSymbol)exceptionToUnmanagedMarshaller.Value
+                };
+            }
             return generatedComInterfaceAttributeData;
         }
     }

src/libraries/System.Runtime.InteropServices/gen/ComInterfaceGenerator/GeneratorDiagnostics.cs

@@ -141,6 +141,15 @@ public class Ids
             DiagnosticSeverity.Error,
             isEnabledByDefault: true);
 
+        public static readonly DiagnosticDescriptor ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode =
+            DiagnosticDescriptorHelper.Create(
+            Ids.InvalidGeneratedComInterfaceAttributeUsage,
+            GetResourceString(nameof(SR.InvalidGeneratedComInterfaceAttributeUsageTitle)),
+            GetResourceString(nameof(SR.ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode)),
+            Category,
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true);
+
         /// <inheritdoc cref="SR.InvalidExceptionMarshallingConfigurationMessage"/>
         public static readonly DiagnosticDescriptor InvalidExceptionMarshallingConfiguration =
             DiagnosticDescriptorHelper.Create(

src/libraries/System.Runtime.InteropServices/gen/ComInterfaceGenerator/VtableIndexStubGenerator.cs

@@ -343,7 +343,7 @@ private static MarshallingInfo CreateExceptionMarshallingInfo(AttributeData virt
 
             if (virtualMethodIndexData.ExceptionMarshalling == ExceptionMarshalling.Com)
             {
-                return new ComExceptionMarshalling();
+                return new ComExceptionMarshalling(null);
             }
             if (virtualMethodIndexData.ExceptionMarshalling == ExceptionMarshalling.Custom)
             {

src/libraries/System.Runtime.InteropServices/gen/Common/Resources/Strings.resx

@@ -916,4 +916,7 @@
   <data name="BaseInterfaceDefinedInOtherAssemblyTitle" xml:space="preserve">
     <value>Specifying 'GeneratedComInterfaceAttribute' on an interface that has a base interface defined in another assembly is not supported</value>
   </data>
+  <data name="ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode" xml:space="preserve">
+    <value>The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</value>
+  </data>
 </root>

src/libraries/System.Runtime.InteropServices/gen/Common/Resources/xlf/Strings.cs.xlf

@@ -392,6 +392,11 @@
         <target state="translated">Zařazovací typ vstupního bodu {0} pro typ {1} musí být typ s nejméně jedním atributem System.Runtime.InteropServices.CustomMarshallerAttribute, který tento typ určuje jako spravovaný typ.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode">
+        <source>The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</source>
+        <target state="new">The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ExtraneousMarshallingInfo">
         <source>Marshalling info was specified for 'ElementIndirectionDepth' {0}, but marshalling info was only needed for {1} level(s) of indirection</source>
         <target state="translated">Informace o zařazování se určily pro ElementIndirectionDepth {0}, ale informace o zařazování byly potřebné pouze pro {1} úrovně indirekce.</target>

src/libraries/System.Runtime.InteropServices/gen/Common/Resources/xlf/Strings.de.xlf

@@ -392,6 +392,11 @@
         <target state="translated">Der Marshallertyp "{0}" des Eintrittspunkts für den Typ "{1}" muss ein Typ mit mindestens einem "System.Runtime.InteropServices.CustomMarshallerAttribute" sein, der diesen Typ als verwalteten Typ angibt</target>
         <note />
       </trans-unit>
+      <trans-unit id="ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode">
+        <source>The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</source>
+        <target state="new">The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ExtraneousMarshallingInfo">
         <source>Marshalling info was specified for 'ElementIndirectionDepth' {0}, but marshalling info was only needed for {1} level(s) of indirection</source>
         <target state="translated">Marshallinginformationen wurden für \"ElementIndirectionDepth\" {0}angegeben. Marshallinginformationen wurden jedoch nur für {1} Dereferenzierungsebene(n) benötigt.</target>

src/libraries/System.Runtime.InteropServices/gen/Common/Resources/xlf/Strings.es.xlf

@@ -392,6 +392,11 @@
         <target state="translated">El tipo de serializador de punto de entrada "{0}" para el tipo "{1}" debe ser un tipo con al menos un "System.Runtime.InteropServices.CustomMarshallerAttribute" que especifique este tipo como el tipo administrado</target>
         <note />
       </trans-unit>
+      <trans-unit id="ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode">
+        <source>The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</source>
+        <target state="new">The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ExtraneousMarshallingInfo">
         <source>Marshalling info was specified for 'ElementIndirectionDepth' {0}, but marshalling info was only needed for {1} level(s) of indirection</source>
         <target state="translated">Se especificó información de serialización para “ElementIndirectionDepth” {0}, pero la información de serialización solo era necesaria para {1} niveles de direccionamiento indirecto</target>

src/libraries/System.Runtime.InteropServices/gen/Common/Resources/xlf/Strings.fr.xlf

@@ -392,6 +392,11 @@
         <target state="translated">Le type de marshaleur de point d’entrée « {0} » pour le type « {1} » doit être un type avec au moins un type « System.Runtime.InteropServices.CustomMarspiaerAttribute » qui spécifie ce type comme type managé</target>
         <note />
       </trans-unit>
+      <trans-unit id="ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode">
+        <source>The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</source>
+        <target state="new">The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ExtraneousMarshallingInfo">
         <source>Marshalling info was specified for 'ElementIndirectionDepth' {0}, but marshalling info was only needed for {1} level(s) of indirection</source>
         <target state="translated">Des informations de marshaling ont été spécifiées pour « ElementIndirectionDepth » {0}, mais les informations de marshaling étaient uniquement nécessaires pour {1} niveau(s) d’indirection</target>

src/libraries/System.Runtime.InteropServices/gen/Common/Resources/xlf/Strings.it.xlf

@@ -392,6 +392,11 @@
         <target state="translated">Il tipo di marshaller del punto di ingresso '{0}' per il tipo '{1}' deve essere un tipo con almeno un elemento 'System.Runtime.InteropServices.CustomMarshallerAttribute' che specifica questo tipo come tipo gestito</target>
         <note />
       </trans-unit>
+      <trans-unit id="ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode">
+        <source>The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</source>
+        <target state="new">The type '{0}' specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not accessible by generated code. The type must have at least 'internal' accessibility. {1}</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ExtraneousMarshallingInfo">
         <source>Marshalling info was specified for 'ElementIndirectionDepth' {0}, but marshalling info was only needed for {1} level(s) of indirection</source>
         <target state="translated">Sono state specificate informazioni di marshalling per l'elemento 'ElementIndirectionDepth' {0}, ma le informazioni di marshalling sono necessarie solo per {1} livello/i di riferimento indiretto</target>