Merge pull request #32919 from mavasani/Issue32842

Handle ICoalesceAssignmentOperation in GetValueUsageInfo(operation) h…

src/EditorFeatures/CSharpTest/RemoveUnusedMembers/RemoveUnusedMembersTests.cs

@@ -2291,5 +2291,28 @@ static partial class B
     </Project>
 </Workspace>");
         }
+
+        [Fact, WorkItem(32842, "https://github.com/dotnet/roslyn/issues/32842")]
+        public async Task FieldIsRead_NullCoalesceAssignment()
+        {
+            await TestDiagnosticMissingAsync(@"
+public class MyClass
+{
+    private MyClass [|_field|];
+    public MyClass Property => _field ??= new MyClass();
+}", new TestParameters(retainNonFixableDiagnostics: true, parseOptions: new CSharpParseOptions(LanguageVersion.CSharp8)));
+        }
+
+        [Fact, WorkItem(32842, "https://github.com/dotnet/roslyn/issues/32842")]
+        public async Task FieldIsNotRead_NullCoalesceAssignment()
+        {
+            await TestDiagnosticsAsync(@"
+public class MyClass
+{
+    private MyClass [|_field|];
+    public void M() => _field ??= new MyClass();
+}", new TestParameters(retainNonFixableDiagnostics: true, parseOptions: new CSharpParseOptions(LanguageVersion.CSharp8)),
+    expected: Diagnostic("IDE0052"));
+        }
     }
 }

src/Features/Core/Portable/RemoveUnusedMembers/AbstractRemoveUnusedMembersDiagnosticAnalyzer.cs

@@ -253,6 +253,8 @@ private void AnalyzeMemberReferenceOperation(OperationAnalysisContext operationC
                     {
                         Debug.Assert(memberReference.Parent is ICompoundAssignmentOperation compoundAssignment &&
                             compoundAssignment.Target == memberReference ||
+                            memberReference.Parent is ICoalesceAssignmentOperation coalesceAssignment &&
+                            coalesceAssignment.Target == memberReference ||
                             memberReference.Parent is IIncrementOrDecrementOperation ||
                             memberReference.Parent is IReDimClauseOperation reDimClause && reDimClause.Operand == memberReference);
 

src/Workspaces/Core/Portable/Extensions/OperationExtensions.cs

@@ -87,7 +87,7 @@ public static ValueUsageInfo GetValueUsageInfo(this IOperation operation)
             if (operation.Parent is IAssignmentOperation assignmentOperation &&
                 assignmentOperation.Target == operation)
             {
-                return operation.Parent.Kind == OperationKind.CompoundAssignment
+                return operation.Parent.Kind == OperationKind.CompoundAssignment || operation.Parent.Kind == OperationKind.CoalesceAssignment
                     ? ValueUsageInfo.ReadWrite
                     : ValueUsageInfo.Write;
             }