Add custom exception handlers to generated COM wrappers

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

@@ -389,14 +389,30 @@ private static IncrementalMethodStubGenerationContext CalculateStubInformation(M
 
             var virtualMethodIndexData = new VirtualMethodIndexData(index, ImplicitThisParameter: true, direction, true, ExceptionMarshalling.Com);
 
+            MarshallingInfo exceptionMarshallingInfo;
+
+            if (generatedComInterfaceAttributeData.ExceptionToUnmanagedMarshaller is null)
+            {
+                exceptionMarshallingInfo = new ComExceptionMarshalling();
+            }
+            else
+            {
+                exceptionMarshallingInfo = CustomMarshallingInfoHelper.CreateNativeMarshallingInfoForNonSignatureElement(
+                    environment.Compilation.GetTypeByMetadataName(TypeNames.System_Exception),
+                    (INamedTypeSymbol)generatedComInterfaceAttributeData.ExceptionToUnmanagedMarshaller,
+                    generatedComAttribute,
+                    environment.Compilation,
+                    generatorDiagnostics);
+            }
+
             return new IncrementalMethodStubGenerationContext(
                 signatureContext,
                 containingSyntaxContext,
                 methodSyntaxTemplate,
                 locations,
                 callConv.ToSequenceEqualImmutableArray(SyntaxEquivalentComparer.Instance),
                 virtualMethodIndexData,
-                new ComExceptionMarshalling(),
+                exceptionMarshallingInfo,
                 environment.EnvironmentFlags,
                 owningInterface,
                 declaringType,

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

@@ -94,6 +94,9 @@ 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 DiagnosticInfo? exceptionToUnmanagedMarshallerDiagnostic))
+                return DiagnosticOrInterfaceInfo.From(exceptionToUnmanagedMarshallerDiagnostic);
+
             InterfaceInfo info = (
                 new ComInterfaceInfo(
                     ManagedTypeInfo.CreateTypeInfoForTypeSymbol(symbol),
@@ -285,6 +288,34 @@ private static bool OptionsAreValid(
             return true;
         }
 
+        private static bool ExceptionToUnmanagedMarshallerIsValid(
+            InterfaceDeclarationSyntax syntax,
+            GeneratedComInterfaceCompilationData attrSymbolInfo,
+            [NotNullWhen(false)] out DiagnosticInfo? exceptionToUnmanagedMarshallerDiagnostic)
+        {
+            if (attrSymbolInfo.ExceptionToUnmanagedMarshaller is INamedTypeSymbol exceptionToUnmanagedMarshallerType)
+            {
+                if (!exceptionToUnmanagedMarshallerType.IsAccessibleFromFileScopedClass(out var details))
+                {
+                    exceptionToUnmanagedMarshallerDiagnostic = DiagnosticInfo.Create(
+                        GeneratorDiagnostics.ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode,
+                        syntax.Identifier.GetLocation(),
+                        exceptionToUnmanagedMarshallerType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat).Replace(TypeNames.GlobalAlias, ""),
+                        details);
+                    return false;
+                }
+            }
+            else if (attrSymbolInfo.ExceptionToUnmanagedMarshaller is not null)
+            {
+                exceptionToUnmanagedMarshallerDiagnostic = DiagnosticInfo.Create(
+                    GeneratorDiagnostics.InvalidExceptionToUnmanagedMarshallerType,
+                    syntax.Identifier.GetLocation());
+                return false;
+            }
+            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

@@ -35,6 +35,7 @@ public static GeneratedComInterfaceData From(GeneratedComInterfaceCompilationDat
     internal sealed record GeneratedComInterfaceCompilationData : InteropAttributeCompilationData
     {
         public ComInterfaceOptions Options { get; init; } = ComInterfaceOptions.ManagedObjectWrapper | ComInterfaceOptions.ComObjectWrapper;
+        public ITypeSymbol? ExceptionToUnmanagedMarshaller { get; init; }
 
         public static bool TryGetGeneratedComInterfaceAttributeFromInterface(INamedTypeSymbol interfaceSymbol, [NotNullWhen(true)] out AttributeData? generatedComInterfaceAttribute)
         {
@@ -70,6 +71,13 @@ public static GeneratedComInterfaceCompilationData GetDataFromAttribute(Attribut
                     Options = (ComInterfaceOptions)options.Value
                 };
             }
+            if (args.TryGetValue(nameof(ExceptionToUnmanagedMarshaller), out TypedConstant exceptionToUnmanagedMarshaller))
+            {
+                generatedComInterfaceAttributeData = generatedComInterfaceAttributeData with
+                {
+                    ExceptionToUnmanagedMarshaller = (ITypeSymbol)exceptionToUnmanagedMarshaller.Value
+                };
+            }
             return generatedComInterfaceAttributeData;
         }
     }

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

@@ -141,6 +141,16 @@ public class Ids
             DiagnosticSeverity.Error,
             isEnabledByDefault: true);
 
+        /// <inheritdoc cref="SR.ExceptionToUnmanagedMarshallerNotAccessibleByGeneratedCode"/>
+        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(
@@ -152,6 +162,16 @@ public class Ids
             isEnabledByDefault: true,
             description: GetResourceString(nameof(SR.InvalidExceptionMarshallingConfigurationDescription)));
 
+        /// <inheritdoc cref="SR.InvalidExceptionToUnmanagedMarshallerType"/>
+        public static readonly DiagnosticDescriptor InvalidExceptionToUnmanagedMarshallerType =
+            DiagnosticDescriptorHelper.Create(
+            Ids.InvalidGeneratedComInterfaceAttributeUsage,
+            GetResourceString(nameof(SR.InvalidGeneratedComInterfaceAttributeUsageTitle)),
+            GetResourceString(nameof(SR.InvalidExceptionToUnmanagedMarshallerType)),
+            Category,
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true);
+
         /// <inheritdoc cref="SR.TypeNotSupportedMessageParameterCom"/>
         public static readonly DiagnosticDescriptor ParameterTypeNotSupported =
             DiagnosticDescriptorHelper.Create(

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

@@ -916,7 +916,13 @@
   <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>
+  <data name="InvalidExceptionToUnmanagedMarshallerType" xml:space="preserve">
+    <value>The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</value>
+  </data>
   <data name="GenericDelegatesNotSupported" xml:space="preserve">
     <value>Marshalling a generic delegate is not supported. Consider using a function pointer instead.</value>
   </data>
-</root>
+</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>
@@ -617,6 +622,11 @@
         <target state="translated">Zadaná hodnota není známý příznak výčtu ExceptionMarsnuming.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InvalidExceptionToUnmanagedMarshallerType">
+        <source>The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</source>
+        <target state="new">The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidGeneratedComClassAttributeUsageDescription">
         <source>Classes with 'GeneratedComClassAttribute' must implement one or more interfaces with 'GeneratedComInterfaceAttribute', be marked partial, and be non-generic.</source>
         <target state="translated">Třídy s třídou GeneratedComClassAttribute musí implementovat jedno nebo více rozhraní s „GeneratedComInterfaceAttribute“, být označeny jako částečné a musí být neobecné.</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>
@@ -617,6 +622,11 @@
         <target state="translated">Der angegebene Wert ist kein bekanntes Flag der „ExceptionMarshalling“-Enumeration.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InvalidExceptionToUnmanagedMarshallerType">
+        <source>The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</source>
+        <target state="new">The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidGeneratedComClassAttributeUsageDescription">
         <source>Classes with 'GeneratedComClassAttribute' must implement one or more interfaces with 'GeneratedComInterfaceAttribute', be marked partial, and be non-generic.</source>
         <target state="translated">Klassen mit "GeneratedComClassAttribute" müssen mindestens eine Schnittstelle mit "GeneratedComInterfaceAttribute" implementieren, als "Partiell" gekennzeichnet und nicht generisch sein.</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>
@@ -617,6 +622,11 @@
         <target state="translated">El valor proporcionado no es una marca conocida de la enumeración “ExceptionMarshalling”.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InvalidExceptionToUnmanagedMarshallerType">
+        <source>The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</source>
+        <target state="new">The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidGeneratedComClassAttributeUsageDescription">
         <source>Classes with 'GeneratedComClassAttribute' must implement one or more interfaces with 'GeneratedComInterfaceAttribute', be marked partial, and be non-generic.</source>
         <target state="translated">Las clases con "GeneratedComClassAttribute" deben implementar una o varias interfaces con "GeneratedComInterfaceAttribute", marcarse como parciales y no ser genéricas.</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>
@@ -617,6 +622,11 @@
         <target state="translated">La valeur fournie n’est pas un indicateur connu de l’énumération « ExceptionMarshalling ».</target>
         <note />
       </trans-unit>
+      <trans-unit id="InvalidExceptionToUnmanagedMarshallerType">
+        <source>The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</source>
+        <target state="new">The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidGeneratedComClassAttributeUsageDescription">
         <source>Classes with 'GeneratedComClassAttribute' must implement one or more interfaces with 'GeneratedComInterfaceAttribute', be marked partial, and be non-generic.</source>
         <target state="translated">Les classes avec 'GeneratedComClassAttribute' doivent implémenter une ou plusieurs interfaces avec 'GeneratedComInterfaceAttribute', être marquées comme partielles et non génériques.</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>
@@ -617,6 +622,11 @@
         <target state="translated">Il valore specificato non è un flag noto dell'enumerazione 'ExceptionMarshalling'.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InvalidExceptionToUnmanagedMarshallerType">
+        <source>The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</source>
+        <target state="new">The type specified as 'GeneratedComInterfaceAttribute.ExceptionToUnmanagedMarshaller' is not a valid marshaller type.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InvalidGeneratedComClassAttributeUsageDescription">
         <source>Classes with 'GeneratedComClassAttribute' must implement one or more interfaces with 'GeneratedComInterfaceAttribute', be marked partial, and be non-generic.</source>
         <target state="translated">Le classi con 'GeneratedComClassAttribute' devono implementare una o più interfacce con 'GeneratedComInterfaceAttribute', essere contrassegnate come parziali e non generiche.</target>