Don't warn about empty initializers on nullable properties in object initializers (#38642)

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

@@ -15790,6 +15790,24 @@ internal class CSharpResources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Object or collection initializer implicitly dereferences possibly null member &apos;{0}&apos;..
+        /// </summary>
+        internal static string WRN_NullReferenceInitializer {
+            get {
+                return ResourceManager.GetString("WRN_NullReferenceInitializer", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Object or collection initializer implicitly dereferences possibly null member..
+        /// </summary>
+        internal static string WRN_NullReferenceInitializer_Title {
+            get {
+                return ResourceManager.GetString("WRN_NullReferenceInitializer_Title", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Possible null reference assignment to iteration variable.
         /// </summary>

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -5753,6 +5753,12 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
   <data name="WRN_MissingNonNullTypesContextForAnnotationInGeneratedCode_Title" xml:space="preserve">
     <value>The annotation for nullable reference types should only be used in code within a '#nullable' annotations context. Auto-generated code requires an explicit '#nullable' directive in source.</value>
   </data>
+  <data name="WRN_NullReferenceInitializer" xml:space="preserve">
+    <value>Object or collection initializer implicitly dereferences possibly null member '{0}'.</value>
+  </data>
+  <data name="WRN_NullReferenceInitializer_Title" xml:space="preserve">
+    <value>Object or collection initializer implicitly dereferences possibly null member.</value>
+  </data>
   <data name="ERR_ExpressionTreeCantContainRefStruct" xml:space="preserve">
     <value>Expression tree cannot contain value of ref struct or restricted type '{0}'.</value>
   </data>

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

@@ -1706,6 +1706,7 @@ internal enum ErrorCode
         WRN_NullabilityMismatchInConstraintsOnPartialImplementation = 8667,
         ERR_NullableDirectiveTargetExpected = 8668,
         WRN_MissingNonNullTypesContextForAnnotationInGeneratedCode = 8669,
+        WRN_NullReferenceInitializer = 8670,
 
         ERR_MultipleAnalyzerConfigsInSameDir = 8700,
 

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

@@ -63,6 +63,7 @@ static ErrorFacts()
             builder.Add(getId(ErrorCode.WRN_NullabilityMismatchInInterfaceImplementedByBase));
             builder.Add(getId(ErrorCode.WRN_DuplicateInterfaceWithNullabilityMismatchInBaseList));
             builder.Add(getId(ErrorCode.WRN_NullabilityMismatchInConstraintsOnPartialImplementation));
+            builder.Add(getId(ErrorCode.WRN_NullReferenceInitializer));
 
             NullableWarnings = builder.ToImmutable();
 
@@ -430,6 +431,7 @@ internal static int GetWarningLevel(ErrorCode code)
                 case ErrorCode.WRN_UndecoratedCancellationTokenParameter:
                 case ErrorCode.WRN_NullabilityMismatchInTypeParameterNotNullConstraint:
                 case ErrorCode.WRN_DisallowNullAttributeForbidsMaybeNullAssignment:
+                case ErrorCode.WRN_NullReferenceInitializer:
                     return 1;
                 default:
                     return 0;

src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs

@@ -1836,9 +1836,12 @@ private void VisitObjectCreationInitializer(Symbol containingSymbol, int contain
 
             void checkImplicitReceiver()
             {
-                if (containingSlot >= 0)
+                if (containingSlot >= 0 && (node as BoundObjectInitializerExpressionBase)?.Initializers.Length != 0)
                 {
-                    _ = ReportPossibleNullReceiverIfNeeded(node.Type, this.State[containingSlot], checkNullableValueType: false, node.Syntax, out _);
+                    if (!node.Type.IsValueType && State[containingSlot].MayBeNull())
+                    {
+                        ReportDiagnostic(ErrorCode.WRN_NullReferenceInitializer, node.Syntax, containingSymbol);
+                    }
                 }
             }
         }

src/Compilers/CSharp/Portable/Generated/ErrorFacts.Generated.cs

@@ -229,6 +229,7 @@ public static bool IsWarning(ErrorCode code)
                 case ErrorCode.WRN_ImplicitCopyInReadOnlyMember:
                 case ErrorCode.WRN_NullabilityMismatchInConstraintsOnPartialImplementation:
                 case ErrorCode.WRN_MissingNonNullTypesContextForAnnotationInGeneratedCode:
+                case ErrorCode.WRN_NullReferenceInitializer:
                 case ErrorCode.WRN_NullabilityMismatchInTypeParameterNotNullConstraint:
                     return true;
                 default:

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

@@ -1492,6 +1492,16 @@
         <target state="translated">Může jít o přiřazení s odkazem null.</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">Možné přiřazení odkazu s hodnotou null k proměnné iterace</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">Mögliche Nullverweiszuweisung.</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">Mögliche Zuweisung eines Nullverweises zu Iterationsvariable</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">Posible asignación de referencia nula</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">Posible asignación de referencia de tipo NULL a variable de iteración</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">Existence possible d'une assignation de référence null.</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">Affectation d'une éventuelle référence null à la variable d'itération</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">Possibile assegnazione di riferimento Null.</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">Possibile assegnazione di riferimento Null alla variabile di iterazione</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">Null 参照割り当ての可能性があります。</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">繰り返し変数に対する null 参照代入の可能性があります</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">가능한 null 참조 할당입니다.</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">반복 변수에 대한 가능한 null 참조 할당</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">Możliwe przypisanie odwołania o wartości null.</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">Możliwe przypisanie odwołania o wartości null do zmiennej iteracji</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">Possível atribuição de referência nula.</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">Possível atribuição de referência nula à variável de iteração</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">Возможно, присваивание-ссылка, допускающее значение NULL.</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">Назначение вероятной пустой ссылки переменной итерации</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">Olası null başvuru ataması.</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">Yineleme değişkenine olası null başvuru ataması</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">可能的 null 引用赋值。</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">迭代变量的可能的空引用赋值</target>

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

@@ -1492,6 +1492,16 @@
         <target state="translated">可能有 Null 參考指派。</target>
         <note />
       </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer">
+        <source>Object or collection initializer implicitly dereferences possibly null member '{0}'.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member '{0}'.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="WRN_NullReferenceInitializer_Title">
+        <source>Object or collection initializer implicitly dereferences possibly null member.</source>
+        <target state="new">Object or collection initializer implicitly dereferences possibly null member.</target>
+        <note />
+      </trans-unit>
       <trans-unit id="WRN_NullReferenceIterationVariable">
         <source>Possible null reference assignment to iteration variable</source>
         <target state="translated">反覆運算變數的可能 null 參考指派</target>

src/Compilers/CSharp/Test/Semantic/Semantics/NullableReferenceTypesTests.cs

@@ -307,15 +307,166 @@ public class C
     public B? f;
     static void Main()
     {
-        new C() { f = { f2 = null, f3 = null }};
+        new C() { f = { f2 = null, f3 = null }}; // 1
     }
 }", options: WithNonNullTypesTrue());
 
             comp.VerifyDiagnostics(
-                // (12,23): warning CS8602: Dereference of a possibly null reference.
-                //         new C() { f = { f2 = null, f3 = null }};
-                Diagnostic(ErrorCode.WRN_NullReferenceReceiver, "{ f2 = null, f3 = null }").WithLocation(12, 23)
-                );
+                // (12,23): warning CS8670: Object or collection initializer implicitly dereferences possibly null member 'C.f'.
+                //         new C() { f = { f2 = null, f3 = null }}; // 1
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ f2 = null, f3 = null }").WithArguments("C.f").WithLocation(12, 23));
+        }
+
+        [Fact, WorkItem(32495, "https://github.com/dotnet/roslyn/issues/32495")]
+        public void CheckImplicitObjectInitializerReceiver_Generic()
+        {
+            var comp = CreateCompilation(@"
+public interface IB
+{
+    object? f2 { get; set; }
+    object? f3 { get; set; }
+}
+
+public struct StructB : IB
+{
+    public object? f2 { get; set; }
+    public object? f3 { get; set; }
+}
+
+public class ClassB : IB
+{
+    public object? f2 { get; set; }
+    public object? f3 { get; set; }
+}
+
+public class C<T> where T : IB?
+{
+    public T f = default!;
+    static void Main()
+    {
+        new C<T>() { f = { f2 = null, f3 = null }}; // 1
+        new C<ClassB>() { f = { f2 = null, f3 = null }};
+        new C<ClassB?>() { f = { f2 = null, f3 = null }}; // 2
+        new C<StructB>() { f = { f2 = null, f3 = null }};
+    }
+}", options: WithNonNullTypesTrue());
+
+            comp.VerifyDiagnostics(
+                // (25,26): warning CS8670: Object or collection initializer implicitly dereferences possibly null member 'C<T>.f'.
+                //         new C<T>() { f = { f2 = null, f3 = null }}; // 1
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ f2 = null, f3 = null }").WithArguments("C<T>.f").WithLocation(25, 26),
+                // (27,32): warning CS8670: Object or collection initializer implicitly dereferences possibly null member 'C<ClassB?>.f'.
+                //         new C<ClassB?>() { f = { f2 = null, f3 = null }}; // 2
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ f2 = null, f3 = null }").WithArguments("C<ClassB?>.f").WithLocation(27, 32));
+        }
+
+        [Fact, WorkItem(38060, "https://github.com/dotnet/roslyn/issues/38060")]
+        public void CheckImplicitObjectInitializerReceiver_EmptyInitializers()
+        {
+            var comp = CreateCompilation(@"
+public class B { }
+public class C
+{
+    public B? f;
+    static void Main()
+    {
+        new C() { f = { }};
+    }
+}", options: WithNonNullTypesTrue());
+
+            comp.VerifyDiagnostics();
+        }
+
+        [Fact, WorkItem(32495, "https://github.com/dotnet/roslyn/issues/32495")]
+        public void CheckImplicitObjectInitializerReceiver_CollectionInitializer()
+        {
+            var comp = CreateCompilation(@"
+using System.Collections;
+
+public class B : IEnumerable
+{
+    public void Add(object o) { }
+    public IEnumerator GetEnumerator() => null!;
+}
+
+public class C
+{
+    public B? f;
+    static void Main()
+    {
+        new C() { f = { new object(), new object() }}; // 1
+    }
+}", options: WithNonNullTypesTrue());
+
+            comp.VerifyDiagnostics(
+                // (15,23): warning CS8670: Object or collection initializer implicitly dereferences nullable member 'C.f'.
+                //         new C() { f = { new object(), new object() }}; // 1
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ new object(), new object() }").WithArguments("C.f").WithLocation(15, 23));
+        }
+
+        [Fact, WorkItem(32495, "https://github.com/dotnet/roslyn/issues/32495")]
+        public void CheckImplicitObjectInitializerReceiver_CollectionInitializer_Generic()
+        {
+            var comp = CreateCompilation(@"
+using System.Collections;
+
+public interface IAddable : IEnumerable
+{
+    void Add(object o);
+}
+
+public class ClassAddable : IAddable
+{
+    public void Add(object o) { }
+    public IEnumerator GetEnumerator() => null!;
+}
+
+public struct StructAddable : IAddable
+{
+    public void Add(object o) { }
+    public IEnumerator GetEnumerator() => null!;
+}
+
+
+public class C<T> where T : IAddable?
+{
+    public T f = default!;
+    static void Main()
+    {
+        new C<T>() { f = { new object(), new object() }}; // 1
+        new C<ClassAddable>() { f = { new object(), new object() }};
+        new C<ClassAddable?>() { f = { new object(), new object() }}; // 2
+        new C<StructAddable>() { f = { new object(), new object() }};
+    }
+}", options: WithNonNullTypesTrue());
+
+            comp.VerifyDiagnostics(
+                // (27,26): warning CS8670: Object or collection initializer implicitly dereferences possibly null member 'C<T>.f'.
+                //         new C<T>() { f = { new object(), new object() }}; // 1
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ new object(), new object() }").WithArguments("C<T>.f").WithLocation(27, 26),
+                // (29,38): warning CS8670: Object or collection initializer implicitly dereferences possibly null member 'C<ClassAddable?>.f'.
+                //         new C<ClassAddable?>() { f = { new object(), new object() }}; // 2
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ new object(), new object() }").WithArguments("C<ClassAddable?>.f").WithLocation(29, 38));
+        }
+
+        [Fact, WorkItem(38060, "https://github.com/dotnet/roslyn/issues/38060")]
+        public void CheckImplicitObjectInitializerReceiver_EmptyCollectionInitializer()
+        {
+            var comp = CreateCompilation(@"
+public class B
+{
+    void Add(object o) { }
+}
+public class C
+{
+    public B? f;
+    static void Main()
+    {
+        new C() { f = { }};
+    }
+}", options: WithNonNullTypesTrue());
+
+            comp.VerifyDiagnostics();
         }
 
         [Fact, WorkItem(32495, "https://github.com/dotnet/roslyn/issues/32495")]
@@ -382,10 +533,9 @@ static void Main()
 }", options: WithNonNullTypesTrue());
 
             comp.VerifyDiagnostics(
-                // (10,25): warning CS8602: Dereference of a possibly null reference.
+                // (10,25): warning CS8670: Object or collection initializer implicitly dereferences possibly null member 'C.this[int]'.
                 //         new C() { [0] = { f2 = null }};
-                Diagnostic(ErrorCode.WRN_NullReferenceReceiver, "{ f2 = null }").WithLocation(10, 25)
-                );
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ f2 = null }").WithArguments("C.this[int]").WithLocation(10, 25));
         }
 
         [Fact, WorkItem(32495, "https://github.com/dotnet/roslyn/issues/32495")]
@@ -407,13 +557,12 @@ static void Main()
 }", options: WithNonNullTypesTrue());
 
             comp.VerifyDiagnostics(
-                // (12,24): warning CS8602: Dereference of a possibly null reference.
+                // (12,24): warning CS8670: Object or collection initializer implicitly dereferences possibly null member 'C.fc'.
                 //         new C() { fc = { fb = { f2 = null} }};
-                Diagnostic(ErrorCode.WRN_NullReferenceReceiver, "{ fb = { f2 = null} }").WithLocation(12, 24),
-                // (12,31): warning CS8602: Dereference of a possibly null reference.
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ fb = { f2 = null} }").WithArguments("C.fc").WithLocation(12, 24),
+                // (12,31): warning CS8670: Object or collection initializer implicitly dereferences possibly null member 'C.fb'.
                 //         new C() { fc = { fb = { f2 = null} }};
-                Diagnostic(ErrorCode.WRN_NullReferenceReceiver, "{ f2 = null}").WithLocation(12, 31)
-                );
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ f2 = null}").WithArguments("C.fb").WithLocation(12, 31));
         }
 
         [Fact, WorkItem(32495, "https://github.com/dotnet/roslyn/issues/32495")]
@@ -434,10 +583,9 @@ static void Main()
 }", options: WithNonNullTypesTrue());
 
             comp.VerifyDiagnostics(
-                // (11,23): warning CS8602: Dereference of a possibly null reference.
+                // (11,23): warning CS8670: Object or collection initializer implicitly dereferences possibly null member 'C.f'.
                 //         new C() { f = { [0] = null }};
-                Diagnostic(ErrorCode.WRN_NullReferenceReceiver, "{ [0] = null }").WithLocation(11, 23)
-                );
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ [0] = null }").WithArguments("C.f").WithLocation(11, 23));
         }
 
         [Fact, WorkItem(32495, "https://github.com/dotnet/roslyn/issues/32495")]
@@ -460,10 +608,9 @@ static void Main()
 }", options: WithNonNullTypesTrue());
 
             comp.VerifyDiagnostics(
-                // (13,23): warning CS8602: Dereference of a possibly null reference.
+                // (13,23): warning CS8670: Object or collection initializer implicitly dereferences possibly null member 'C.f'.
                 //         new C() { f = { 1 }};
-                Diagnostic(ErrorCode.WRN_NullReferenceReceiver, "{ 1 }").WithLocation(13, 23)
-                );
+                Diagnostic(ErrorCode.WRN_NullReferenceInitializer, "{ 1 }").WithArguments("C.f").WithLocation(13, 23));
         }
 
         [Fact, WorkItem(29964, "https://github.com/dotnet/roslyn/issues/29964")]

src/Compilers/CSharp/Test/Syntax/Diagnostics/DiagnosticTest.cs

@@ -309,6 +309,7 @@ public void WarningLevel_2()
                         case ErrorCode.WRN_SwitchExpressionNotExhaustiveForNull:
                         case ErrorCode.WRN_ImplicitCopyInReadOnlyMember:
                         case ErrorCode.WRN_NullabilityMismatchInTypeParameterNotNullConstraint:
+                        case ErrorCode.WRN_NullReferenceInitializer:
                             Assert.Equal(1, ErrorFacts.GetWarningLevel(errorCode));
                             break;
                         case ErrorCode.WRN_InvalidVersionFormat: