fix

src/Analyzers.CodeFixes/CSharp/CodeFixes/AddOrRemoveTrailingCommaCodeFixProvider.cs

@@ -36,7 +36,8 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
                 SyntaxKind.ObjectInitializerExpression,
                 SyntaxKind.CollectionInitializerExpression,
                 SyntaxKind.EnumDeclaration,
-                SyntaxKind.AnonymousObjectCreationExpression)))
+                SyntaxKind.AnonymousObjectCreationExpression,
+                SyntaxKind.CollectionExpression)))
         {
             return;
         }
@@ -69,6 +70,31 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
                 context.RegisterCodeFix(codeAction, diagnostic);
             }
         }
+        if (node is CollectionExpressionSyntax collectionExpression)
+        {
+            SeparatedSyntaxList<CollectionElementSyntax> elements = collectionExpression.Elements;
+
+            int count = elements.Count;
+
+            if (count == elements.SeparatorCount)
+            {
+                CodeAction codeAction = CodeAction.Create(
+                    "Remove comma",
+                    ct => RemoveTrailingComma(document, elements.GetSeparator(count - 1), ct),
+                    GetEquivalenceKey(diagnostic));
+
+                context.RegisterCodeFix(codeAction, diagnostic);
+            }
+            else
+            {
+                CodeAction codeAction = CodeAction.Create(
+                    "Add comma",
+                    ct => AddTrailingComma(document, elements.Last(), ct),
+                    GetEquivalenceKey(diagnostic));
+
+                context.RegisterCodeFix(codeAction, diagnostic);
+            }
+        }
         else if (node is AnonymousObjectCreationExpressionSyntax objectCreation)
         {
             SeparatedSyntaxList<AnonymousObjectMemberDeclaratorSyntax> initializers = objectCreation.Initializers;

src/Analyzers/CSharp/Analysis/AddOrRemoveTrailingCommaAnalyzer.cs

@@ -32,6 +32,7 @@ public override void Initialize(AnalysisContext context)
 
         context.RegisterSyntaxNodeAction(f => AnalyzeEnumDeclaration(f), SyntaxKind.EnumDeclaration);
         context.RegisterSyntaxNodeAction(f => AnalyzeAnonymousObjectCreationExpression(f), SyntaxKind.AnonymousObjectCreationExpression);
+        context.RegisterSyntaxNodeAction(f => AnalyzeCollectionExpression(f), SyntaxKind.CollectionExpression);
 
         context.RegisterSyntaxNodeAction(
             f => AnalyzeInitializerExpression(f),
@@ -169,6 +170,49 @@ private static void AnalyzeAnonymousObjectCreationExpression(SyntaxNodeAnalysisC
         }
     }
 
+    private static void AnalyzeCollectionExpression(SyntaxNodeAnalysisContext context)
+    {
+        TrailingCommaStyle style = context.GetTrailingCommaStyle();
+
+        if (style == TrailingCommaStyle.None)
+            return;
+
+        var objectCreation = (CollectionExpressionSyntax)context.Node;
+
+        SeparatedSyntaxList<CollectionElementSyntax> elements = objectCreation.Elements;
+
+        if (!elements.Any())
+            return;
+
+        int count = elements.Count;
+        int separatorCount = elements.SeparatorCount;
+
+        if (count == separatorCount)
+        {
+            if (style == TrailingCommaStyle.Omit)
+            {
+                ReportRemove(context, elements.GetSeparator(count - 1));
+            }
+            else if (style == TrailingCommaStyle.OmitWhenSingleLine
+                     && elements.IsSingleLine(cancellationToken: context.CancellationToken))
+            {
+                ReportRemove(context, elements.GetSeparator(count - 1));
+            }
+        }
+        else if (separatorCount == count - 1)
+        {
+            if (style == TrailingCommaStyle.Include)
+            {
+                ReportAdd(context, elements.Last());
+            }
+            else if (style == TrailingCommaStyle.OmitWhenSingleLine
+                     && !elements.IsSingleLine(cancellationToken: context.CancellationToken))
+            {
+                ReportAdd(context, elements.Last());
+            }
+        }
+    }
+
     private static void ReportAdd(SyntaxNodeAnalysisContext context, SyntaxNode lastNode)
     {
         DiagnosticHelpers.ReportDiagnostic(

src/Tests/Analyzers.Tests/RCS1260AddOrRemoveTrailingCommaTests.cs

@@ -329,4 +329,48 @@ void M()
 }
 """, options: Options.AddConfigOption(ConfigOptionKeys.TrailingCommaStyle, ConfigOptionValues.TrailingCommaStyle_OmitWhenSingleLine));
     }
+        [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.AddOrRemoveTrailingComma)]
+    public async Task Test_CollectionExpression_Omit()
+    {
+        await VerifyDiagnosticAndFixAsync("""
+class C
+{
+    void M()
+    {
+        int[] x = [1, 2, 3[|,|]];
+    }
+}
+""", """
+class C
+{
+    void M()
+    {
+        int[] x = [1, 2, 3];
+    }
+}
+""", options: Options.AddConfigOption(ConfigOptionKeys.TrailingCommaStyle, ConfigOptionValues.TrailingCommaStyle_Omit));
+    }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.AddOrRemoveTrailingComma)]
+    public async Task Test_CollectionExpression_OmitWhenSingleLine()
+    {
+        await VerifyDiagnosticAndFixAsync("""
+class C
+{
+    void M()
+    {
+        int[] x = [1, 2, 3[|,|]];
+    }
+}
+""", """
+     class C
+     {
+         void M()
+         {
+             int[] x = [1, 2, 3];
+         }
+     }
+     """, options: Options.AddConfigOption(ConfigOptionKeys.TrailingCommaStyle, ConfigOptionValues.TrailingCommaStyle_OmitWhenSingleLine));
+    }
+
 }