Merge pull request #32571 from YairHalberstadt/AllowObsoleteOnAccessor

Allow Obsolete Attribute on Accessors

src/Compilers/CSharp/Portable/Binder/Binder_Attributes.cs

@@ -366,6 +366,16 @@ private BoundExpression BindNamedAttributeArgument(AttributeArgumentSyntax named
 
             ReportDiagnosticsIfObsolete(diagnostics, namedArgumentNameSymbol, namedArgument, hasBaseReceiver: false);
 
+            if (namedArgumentNameSymbol.Kind == SymbolKind.Property)
+            {
+                var propertySymbol = (PropertySymbol)namedArgumentNameSymbol;
+                var setMethod = propertySymbol.GetOwnOrInheritedSetMethod();
+                if (setMethod != null)
+                {
+                    ReportDiagnosticsIfObsolete(diagnostics, setMethod, namedArgument, hasBaseReceiver: false);
+                }
+            }
+
             Debug.Assert(resultKind == LookupResultKind.Viable || wasError);
 
             TypeSymbol namedArgumentType;

src/Compilers/CSharp/Portable/CSharpResources.Designer.cs

@@ -762,6 +762,15 @@ internal class CSharpResources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Attribute &apos;{0}&apos; is not valid on event accessors. It is only valid on &apos;{1}&apos; declarations..
+        /// </summary>
+        internal static string ERR_AttributeNotOnEventAccessor {
+            get {
+                return ResourceManager.GetString("ERR_AttributeNotOnEventAccessor", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Attribute &apos;{0}&apos; is not valid on this declaration type. It is only valid on &apos;{1}&apos; declarations..
         /// </summary>
@@ -11401,6 +11410,15 @@ internal class CSharpResources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to obsolete on property accessor.
+        /// </summary>
+        internal static string IDS_FeatureObsoleteOnPropertyAccessor {
+            get {
+                return ResourceManager.GetString("IDS_FeatureObsoleteOnPropertyAccessor", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to optional parameter.
         /// </summary>

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -5829,4 +5829,10 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
   <data name="WRN_SwitchExpressionNotExhaustiveForNull_Title" xml:space="preserve">
     <value>The switch expression does not handle some null inputs.</value>
   </data>
-</root>
+  <data name="ERR_AttributeNotOnEventAccessor" xml:space="preserve">
+    <value>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</value>
+  </data>
+  <data name="IDS_FeatureObsoleteOnPropertyAccessor" xml:space="preserve">
+    <value>obsolete on property accessor</value>
+  </data>
+</root>
\ No newline at end of file

src/Compilers/CSharp/Portable/Errors/ErrorCode.cs

@@ -1598,7 +1598,7 @@ internal enum ErrorCode
         ERR_PossibleAsyncIteratorWithoutYieldOrAwait = 8420,
         ERR_StaticLocalFunctionCannotCaptureVariable = 8421,
         ERR_StaticLocalFunctionCannotCaptureThis = 8422,
-
+        ERR_AttributeNotOnEventAccessor = 8423,
         #region diagnostics introduced for recursive patterns
         // 8501, // available
         ERR_WrongNumberOfSubpatterns = 8502,

src/Compilers/CSharp/Portable/Errors/MessageID.cs

@@ -175,7 +175,8 @@ internal enum MessageID
         IDS_FeatureStaticLocalFunctions = MessageBase + 12755,
         IDS_FeatureNameShadowingInNestedFunctions = MessageBase + 12756,
         IDS_FeatureUnmanagedConstructedTypes = MessageBase + 12757,
-
+        IDS_FeatureObsoleteOnPropertyAccessor = MessageBase + 12758,
+        
         IDS_DefaultInterfaceImplementation = MessageBase + 12800,
         IDS_BaseTypeInBaseExpression = MessageBase + 12801,
     }
@@ -282,6 +283,7 @@ internal static LanguageVersion RequiredVersion(this MessageID feature)
                 case MessageID.IDS_FeatureStaticLocalFunctions:
                 case MessageID.IDS_FeatureNameShadowingInNestedFunctions:
                 case MessageID.IDS_FeatureUnmanagedConstructedTypes: // semantic check
+                case MessageID.IDS_FeatureObsoleteOnPropertyAccessor:
                 case MessageID.IDS_DefaultInterfaceImplementation: // semantic check
                 case MessageID.IDS_BaseTypeInBaseExpression:
                     return LanguageVersion.CSharp8;

src/Compilers/CSharp/Portable/Symbols/ObsoleteAttributeHelpers.cs

@@ -55,12 +55,7 @@ private static ThreeState GetObsoleteContextState(Symbol symbol, bool forceCompl
         {
             while ((object)symbol != null)
             {
-                // For property or event accessors, check the associated property or event instead.
-                if (symbol.IsAccessor())
-                {
-                    symbol = ((MethodSymbol)symbol).AssociatedSymbol;
-                }
-                else if (symbol.Kind == SymbolKind.Field)
+                if (symbol.Kind == SymbolKind.Field)
                 {
                     // If this is the backing field of an event, look at the event instead.
                     var associatedSymbol = ((FieldSymbol)symbol).AssociatedSymbol;
@@ -81,7 +76,15 @@ private static ThreeState GetObsoleteContextState(Symbol symbol, bool forceCompl
                     return state;
                 }
 
-                symbol = symbol.ContainingSymbol;
+                // For property or event accessors, check the associated property or event next.
+                if (symbol.IsAccessor())
+                {
+                    symbol = ((MethodSymbol)symbol).AssociatedSymbol;
+                }
+                else
+                {
+                    symbol = symbol.ContainingSymbol;
+                }
             }
 
             return ThreeState.False;

src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberMethodSymbol.cs

@@ -1222,9 +1222,16 @@ private void DecodeWellKnownAttributeAppliedToMethod(ref DecodeWellKnownAttribut
             {
                 if (this.IsAccessor())
                 {
-                    // CS1667: Attribute '{0}' is not valid on property or event accessors. It is only valid on '{1}' declarations.
-                    AttributeUsageInfo attributeUsage = arguments.Attribute.AttributeClass.GetAttributeUsageInfo();
-                    arguments.Diagnostics.Add(ErrorCode.ERR_AttributeNotOnAccessor, arguments.AttributeSyntaxOpt.Name.Location, description.FullName, attributeUsage.GetValidTargetsErrorArgument());
+                    if (this is SourceEventAccessorSymbol)
+                    {
+                        // CS1667: Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.
+                        AttributeUsageInfo attributeUsage = arguments.Attribute.AttributeClass.GetAttributeUsageInfo();
+                        arguments.Diagnostics.Add(ErrorCode.ERR_AttributeNotOnEventAccessor, arguments.AttributeSyntaxOpt.Name.Location, description.FullName, attributeUsage.GetValidTargetsErrorArgument());
+                    }
+                    else
+                    {
+                        MessageID.IDS_FeatureObsoleteOnPropertyAccessor.CheckFeatureAvailability(arguments.Diagnostics, arguments.AttributeSyntaxOpt.Location);
+                    }
                 }
 
                 return true;

src/Compilers/CSharp/Portable/xlf/CSharpResources.cs.xlf

@@ -32,6 +32,11 @@
         <target state="translated">Ve výrazu as se nepovoluje použití typu odkazu s možnou hodnotou null {0}?; místo toho použijte základní typ {0}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">Asynchronní příkaz foreach nejde použít pro proměnné typu {0}, protože {0} neobsahuje vhodnou veřejnou definici instance pro {1}.</target>
@@ -742,6 +747,11 @@
         <target state="translated">omezení obecného typu objektu</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">akce varování enable nebo safeonly</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.de.xlf

@@ -32,6 +32,11 @@
         <target state="translated">Es ist unzulässig, den Nullable-Verweistyp "{0}?" in einem as-Ausdruck zu verwenden. Verwenden Sie stattdessen den zugrunde liegenden Typ "{0}".</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">Eine asynchrone foreach-Anweisung kann nicht für Variablen vom Typ "{0}" verwendet werden, weil "{0}" keine geeignete öffentliche Instanzdefinition für "{1}" enthält.</target>
@@ -742,6 +747,11 @@
         <target state="translated">Einschränkung eines generischen Objekttyps</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">Warnaktion: "enable" oder "safeonly"</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.es.xlf

@@ -32,6 +32,11 @@
         <target state="translated">No se puede usar el tipo "{0}?" que acepta valores NULL en una expresión as; use en su lugar el tipo "{0}" subyacente.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">Una instrucción foreach asincrónica no puede funcionar en variables de tipo "{0}", porque "{0}" no contiene una definición de instancia pública adecuada para "{1}".</target>
@@ -744,6 +749,11 @@
         <target state="translated">restricción de tipo genérico de objeto</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">acción de advertencia "enable" o "safeonly"</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.fr.xlf

@@ -32,6 +32,11 @@
         <target state="translated">Il n'est pas correct d'utiliser le type de référence Nullable '{0}?' dans une expression as. Utilisez le type sous-jacent '{0}' à la place.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">L'instruction foreach asynchrone ne peut pas fonctionner sur des variables de type '{0}', car '{0}' ne contient aucune définition d'instance publique appropriée pour '{1}'</target>
@@ -743,6 +748,11 @@
         <target state="translated">contrainte de type générique d'objet</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">action d'avertissement enable ou safeonly</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.it.xlf

@@ -32,6 +32,11 @@
         <target state="translated">Non è consentito usare il tipo riferimento nullable '{0}?' in un'espressione as. Usare il tipo sottostante '{0}'.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">L'istruzione foreach asincrona non può funzionare con variabili di tipo '{0}' perché '{0}' non contiene una definizione di istanza pubblica idonea per '{1}'</target>
@@ -742,6 +747,11 @@
         <target state="translated">vincolo di tipo generico object</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">azione di avviso enable o safeonly</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.ja.xlf

@@ -32,6 +32,11 @@
         <target state="translated">as 式で Null 許容参照型 '{0}?' を使用することはできません。代わりに基になる型 '{0}' をご使用ください。</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">'{0}' は '{1}' の適切なパブリック インスタンス定義を含んでいないため、型 '{0}' の変数に対して非同期 foreach ステートメントを使用することはできません</target>
@@ -742,6 +747,11 @@
         <target state="translated">オブジェクト ジェネリック型の制約</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">警告アクション enable または safeonly</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.ko.xlf

@@ -32,6 +32,11 @@
         <target state="translated">식에 nullable 참조 형식 '{0}'을(를) 사용하는 것은 올바르지 않습니다. 대신 기본 형식 '{0}'을(를) 사용하세요.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">'{0}' 형식 변수에서 비동기 foreach 문을 수행할 수 없습니다. '{0}'에는 '{1}'의 적합한 공용 인스턴스 정의가 없기 때문입니다.</target>
@@ -742,6 +747,11 @@
         <target state="translated">개체 제네릭 형식 제약 조건</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">경고 작업 enable 또는 safeonly</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.pl.xlf

@@ -32,6 +32,11 @@
         <target state="translated">Użycie typu odwołania dopuszczającego wartość null „{0}?” w wyrażeniu „as” jest niedozwolone. Zamiast tego użyj bazowego typu „{0}”.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">Asynchroniczna instrukcja foreach nie może operować na zmiennych typu „{0}”, ponieważ typ „{0}” nie zawiera odpowiedniej publicznej definicji wystąpienia elementu „{1}”</target>
@@ -742,6 +747,11 @@
         <target state="translated">ogólne ograniczenie typu obiektu</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">akcja warning: enable lub safeonly</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.pt-BR.xlf

@@ -32,6 +32,11 @@
         <target state="translated">É ilegal usar o tipo de referência anulável '{0}?' em uma expressão as; use o tipo subjacente '{0}' em seu lugar.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">A instrução foreach assíncrona não pode operar em variáveis do tipo '{0}' porque '{0}' não contém uma definição da instância pública adequada para '{1}'</target>
@@ -742,6 +747,11 @@
         <target state="translated">restrição de tipo genérico de objeto</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">ação de aviso enable ou safeonly</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.ru.xlf

@@ -32,6 +32,11 @@
         <target state="translated">Недопустимо использовать ссылочный тип "{0}", допускающий значения NULL, в выражении "as". Используйте вместо него базовый тип "{0}".</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">Асинхронный оператор foreach не работает с переменными типа "{0}", так как "{0}" не содержит подходящее открытое определение экземпляра для "{1}".</target>
@@ -742,6 +747,11 @@
         <target state="translated">ограничение универсального типа для объекта</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">действие warning с enable или safeonly</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.tr.xlf

@@ -32,6 +32,11 @@
         <target state="translated">Boş değer atanabilir '{0}?' başvuru türünün bir as ifadesinde kullanılması yasaktır; bunun yerine temel alınan '{0}' türünü kullanın.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">'{0}', '{1}' için uygun bir genel örnek tanımı içermediğinden zaman uyumsuz foreach deyimi '{0}' türündeki değişkenlerle çalışmaz</target>
@@ -743,6 +748,11 @@
         <target state="translated">nesne genel tür kısıtlamaları</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">enable veya safeonly uyarı eylemi</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.zh-Hans.xlf

@@ -32,6 +32,11 @@
         <target state="translated">在 as 表达式中使用可以为 null 的引用类型“{0}?”是非法的；请改用基础类型“{0}”。</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">“{0}”不包含“{1}”的适当公共实例定义，因此异步 foreach 语句不能作用于“{0}”类型的变量</target>
@@ -783,6 +788,11 @@
         <target state="translated">对象泛型类型约束</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">警告操作 enable 或 safeonly</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.zh-Hant.xlf

@@ -32,6 +32,11 @@
         <target state="translated">在運算式中使用可為 Null 的參考型別 '{0}?' 不合法，請改用基礎類型 '{0}'。</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_AttributeNotOnEventAccessor">
+        <source>Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</source>
+        <target state="new">Attribute '{0}' is not valid on event accessors. It is only valid on '{1}' declarations.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_AwaitForEachMissingMember">
         <source>Asynchronous foreach statement cannot operate on variables of type '{0}' because '{0}' does not contain a suitable public instance definition for '{1}'</source>
         <target state="translated">因為 '{0}' 不包含適用於 '{1}' 的公用執行個體定義，所以非同步的 foreach 陳述式無法在類型為 '{0}' 的變數上運作</target>
@@ -742,6 +747,11 @@
         <target state="translated">物件泛型型別條件約束</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureObsoleteOnPropertyAccessor">
+        <source>obsolete on property accessor</source>
+        <target state="new">obsolete on property accessor</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeaturePragmaWarningEnableOrSafeOnly">
         <source>warning action enable or safeonly</source>
         <target state="translated">警告動作 enable 或 safeonly</target>

src/Compilers/CSharp/Test/Symbol/Symbols/SymbolErrorTests.cs

@@ -15233,9 +15233,6 @@ public static void Main()
 }
 ";
             var comp = CreateCompilation(text).VerifyDiagnostics(
-    // (8,10): error CS1667: Attribute 'Obsolete' is not valid on property or event accessors. It is only valid on 'class, struct, enum, constructor, method, property, indexer, field, event, interface, delegate' declarations.
-    //         [Obsolete]  // CS1667
-    Diagnostic(ErrorCode.ERR_AttributeNotOnAccessor, "Obsolete").WithArguments("System.ObsoleteAttribute", "class, struct, enum, constructor, method, property, indexer, field, event, interface, delegate"),
     // (10,10): error CS1667: Attribute 'System.Diagnostics.Conditional' is not valid on property or event accessors. It is only valid on 'class, method' declarations.
     //         [System.Diagnostics.Conditional("Bernard")]
     Diagnostic(ErrorCode.ERR_AttributeNotOnAccessor, "System.Diagnostics.Conditional").WithArguments("System.Diagnostics.Conditional", "class, method")