Do not say the wrong default behavior for blittable arrays in ComInterfaceGenerator warning

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Marshalling/ByValueContentsMarshalKindValidator.cs

@@ -44,6 +44,13 @@ private static ResolvedGenerator ValidateByValueMarshalKind(TypePositionInfo inf
             }
             else if (info.ByValueContentsMarshalKind == ByValueContentsMarshalKind.In)
             {
+                if (info.ManagedType is SzArrayType && generator.Generator is StaticPinnableManagedValueMarshaller)
+                {
+                    return ResolvedGenerator.ResolvedWithDiagnostics(s_forwarder, generator.Diagnostics.Add(new GeneratorDiagnostic.NotSupported(info, context)
+                    {
+                        NotSupportedDetails = SR.InAttributeNotSupportedWithoutOutBlittableArray
+                    }));
+                }
                 return ResolvedGenerator.ResolvedWithDiagnostics(s_forwarder, generator.Diagnostics.Add(new GeneratorDiagnostic.NotSupported(info, context)
                 {
                     NotSupportedDetails = SR.InAttributeNotSupportedWithoutOut

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/Strings.resx

@@ -195,4 +195,7 @@
   <data name="InOutAttributes" xml:space="preserve">
     <value>[In] and [Out] attributes</value>
   </data>
+  <data name="InAttributeNotSupportedWithoutOutBlittableArray" xml:space="preserve">
+    <value>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</value>
+  </data>
 </root>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.cs.xlf

@@ -57,6 +57,11 @@
         <target state="translated">Atribut „[In]“ se nepodporuje, pokud není zároveň použit i atribut „[Out]“. Chování atributu „[In]“ bez atributu „[Out]“ je stejné, jako výchozí chování.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">Atributy „[In]“ a „[Out]“ se nepodporují u parametrů předaných odkazem. Použijte místo nich klíčová slova „in“, „ref“ nebo „out“.</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.de.xlf

@@ -57,6 +57,11 @@
         <target state="translated">Das [In]-Attribut wird nur unterstützt, wenn auch das [Out]-Attribut verwendet wird. Das Verhalten des [In]-Attributs ohne das [Out]-Attribut entspricht dem Standardverhalten.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">Die Attribute \"[In]\" und \"[Out]\" werden für Parameter, die als Verweis übergeben werden, nicht unterstützt. Verwenden Sie stattdessen die Schlüsselwörter \"in\", \"ref\" oder \"out\".</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.es.xlf

@@ -57,6 +57,11 @@
         <target state="translated">No se admite el atributo “[In]” a menos que también se use el atributo “[Out]”. El comportamiento del atributo “[In]” sin el atributo “[Out]” es el mismo que el predeterminado.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">Los atributos “[In]” y “[Out]” no se admiten en los parámetros pasados por referencia. Use las palabras clave “in”, “ref” o “out” en su lugar.</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.fr.xlf

@@ -57,6 +57,11 @@
         <target state="translated">L’attribut « [In] » n’est pas pris en charge, sauf si l’attribut « [Out] » est également utilisé. Le comportement de l’attribut « [In] »sans l’attribut « [Out] » est identique au comportement par défaut.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">Les attributs « [In] » et « [Out] » ne sont pas pris en charge sur les paramètres passés par référence. Utilisez les mots clés « in », « ref » ou 'out' à la place.</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.it.xlf

@@ -57,6 +57,11 @@
         <target state="translated">L'attributo '[In]' non è supportato a meno che non venga usato anche l'attributo '[Out]'. Il comportamento dell'attributo '[In]' senza l'attributo '[Out]' è uguale a quello predefinito.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">Gli attributi '[In]' e '[Out]' non sono supportati nei parametri passati per riferimento. Usare le parole chiave 'in', 'ref' o 'out'.</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.ja.xlf

@@ -57,6 +57,11 @@
         <target state="translated">'[In]' 属性は、'[Out]' 属性も使用しない限りサポートされません。'[Out]' 属性なしでの '[In]' 属性の動作は、既定の動作と同じです。</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">'[In]' 属性と '[Out]' 属性は、参照渡しされたパラメーターではサポートされていません。代わりに 'in'、'ref'、または 'out' キーワードを使用します。</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.ko.xlf

@@ -57,6 +57,11 @@
         <target state="translated">'[In]' 특성은 '[Out]' 특성도 함께 사용되지 않는 한 지원되지 않습니다. '[Out]' 특성이 없는 '[In]' 특성의 동작은 기본 동작과 동일합니다.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">'[In]' 및 '[Out]' 특성은 참조로 전달된 매개 변수에서 지원되지 않습니다. 대신 'in', 'ref' 또는 'out' 키워드를 사용하세요.</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.pl.xlf

@@ -57,6 +57,11 @@
         <target state="translated">Atrybut „[In]” nie jest obsługiwany, chyba że używany jest również atrybut „[Out]”. Zachowanie atrybutu „[In]” bez atrybutu „[Out]” jest takie samo jak zachowanie domyślne.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">Atrybuty „[In]” i „[Out]” nie są obsługiwane w parametrach przekazywanych przez odwołanie. Zamiast tego użyj słów kluczowych „in”, „ref” lub „out”.</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.pt-BR.xlf

@@ -57,6 +57,11 @@
         <target state="translated">O atributo '[In]' não tem suporte, a menos que o '[Out]' também seja usado. O comportamento do atributo '[In]' sem o atributo '[Out]' é o mesmo que o comportamento padrão.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">Os atributos '[In]' e '[Out]' não têm suporte em parâmetros passados por referência. Use as palavras-chave 'in', 'ref' ou 'out'.</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.ru.xlf

@@ -57,6 +57,11 @@
         <target state="translated">Атрибут \"[In]\" не поддерживается, если атрибут \"[Out]' не используется. Поведение атрибута \"[In]\" без \"[Out]\" совпадает с поведением по умолчанию.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">Атрибуты \"[In]\" и \"[Out]\" не поддерживаются для параметров, передаваемых по ссылке. Используйте вместо них ключевые слова \"in\", \"ref\" или \"out\".</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.tr.xlf

@@ -57,6 +57,11 @@
         <target state="translated">'[Out]' özniteliği de kullanılmadığı sürece '[In]' özniteliği desteklenmiyor. '[Out]' özniteliği kullanılmadığında '[In]' özniteliğinin davranışı varsayılan davranışla aynı olacaktır.</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">'[In]' ve '[Out]' öznitelikleri başvuruya göre aktarılan parametrelerde desteklenmiyor. Bunun yerine 'in', 'ref' veya 'out' anahtar sözcüklerini kullanın.</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.zh-Hans.xlf

@@ -57,6 +57,11 @@
         <target state="translated">不支持 “[In]” 属性，除非同时使用 “[Out]” 属性。没有 “[Out]” 属性的情况下，“[In]” 属性的行为与默认行为相同。</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">引用传递的参数不支持 “[In]” 和 “[Out]” 属性。请改用 “in”、“ref” 或 “out” 关键字。</target>

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/Resources/xlf/Strings.zh-Hant.xlf

@@ -57,6 +57,11 @@
         <target state="translated">除非一併使用'[Out]'屬性，否則不支援'[In]'屬性。沒有'[Out]'屬性的'[In]'屬性行為與默認行為相同。</target>
         <note />
       </trans-unit>
+      <trans-unit id="InAttributeNotSupportedWithoutOutBlittableArray">
+        <source>The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</source>
+        <target state="new">The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="InOutAttributeByRefNotSupported">
         <source>The '[In]' and '[Out]' attributes are unsupported on parameters passed by reference. Use the 'in', 'ref', or 'out' keywords instead.</source>
         <target state="translated">參考所傳遞的參數不支援'[In]'和'[Out]'屬性。請改用 'in'、'ref' 或 'out' 關鍵詞。</target>

src/libraries/System.Runtime.InteropServices/tests/ComInterfaceGenerator.Unit.Tests/CodeSnippets.cs

@@ -51,6 +51,17 @@ private string UnmanagedCallConv(Type[]? CallConvs = null)
 
         public static readonly string DisableRuntimeMarshalling = "[assembly:System.Runtime.CompilerServices.DisableRuntimeMarshalling]";
         public static readonly string UsingSystemRuntimeInteropServicesMarshalling = "using System.Runtime.InteropServices.Marshalling;";
+        public string InAttributedBlittableArray => $$"""
+            using System.Runtime.InteropServices;
+            using System.Runtime.InteropServices.Marshalling;
+
+            {{GeneratedComInterface()}}
+            partial interface INativeAPI
+            {
+                {{VirtualMethodIndex(0)}}
+                void Method([InAttribute] int[] parameter);
+            }
+            """;
 
         public string SpecifiedMethodIndexNoExplicitParameters => $$"""
             using System.Runtime.InteropServices;

src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CompileFails.cs

@@ -3,9 +3,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Collections.Immutable;
-using System.IO;
-using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Threading.Tasks;
@@ -834,6 +831,21 @@ public static IEnumerable<object[]> CodeSnippetsToCompile()
                     .WithLocation(1)
                     .WithArguments("ref return", "Basic.RefReadonlyReturn()"),
             } };
+            yield return new object[] { ID(), CodeSnippets.ByValueParameterWithModifier<int[]>("In"), new[]
+            {
+                VerifyCS.Diagnostic(GeneratorDiagnostics.ParameterTypeNotSupportedWithDetails)
+                    .WithLocation(0)
+                    .WithArguments("The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.", "p")
+            } };
+        }
+        public static IEnumerable<object[]> MyCodeSnippetsToCompile()
+        {
+            yield return new object[] { ID(), CodeSnippets.ByValueParameterWithModifier<int[]>("In"), new[]
+            {
+                VerifyCS.Diagnostic(GeneratorDiagnostics.ParameterTypeNotSupportedWithDetails)
+                    .WithLocation(0)
+                    .WithArguments("The '[In]' attribute is not supported unless the '[Out]' attribute is also used. Blittable arrays cannot be marshalled as '[In]' only.", "p")
+            } };
         }
 
         [Theory]
@@ -945,7 +957,7 @@ public async Task ValidateRequireAllowUnsafeBlocksDiagnostic()
         class AllowUnsafeBlocksTest : VerifyCS.Test
         {
             public AllowUnsafeBlocksTest()
-                    :base(referenceAncillaryInterop: false)
+                    : base(referenceAncillaryInterop: false)
             {
             }