Add analyzer 'Add/remove trailing comma'

.editorconfig

@@ -45,6 +45,7 @@ roslynator_doc_comment_summary_style = multi_line
 roslynator_enum_flag_value_style = shift_operator
 roslynator_blank_line_after_file_scoped_namespace_declaration = true
 roslynator_null_check_style = pattern_matching
+roslynator_trailing_comma_style = omit_when_single_line
 
 dotnet_diagnostic.RCS0001.severity = suggestion
 dotnet_diagnostic.RCS0003.severity = suggestion
@@ -146,6 +147,7 @@ dotnet_diagnostic.RCS1252.severity = suggestion
 dotnet_diagnostic.RCS1253.severity = suggestion
 dotnet_diagnostic.RCS1254.severity = suggestion
 dotnet_diagnostic.RCS1255.severity = none
+dotnet_diagnostic.RCS1260.severity = suggestion
 
 dotnet_diagnostic.IDE0007.severity = none
 dotnet_diagnostic.IDE0007WithoutSuggestion.severity = none

ChangeLog.md

@@ -27,6 +27,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
     - Remove empty region directive ([RCS1091](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1091))
     - Remove empty destructor ([RCS1106](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1106))
 - [CLI] Add glob pattern matching (`--include` or/and `--exclude`) ([#1178](https://github.com/josefpihrt/roslynator/pull/1178), [#1183](https://github.com/josefpihrt/roslynator/pull/1183)).
+- Add analyzer "Include/omit trailing comma" ([RCS1256](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1256.md)) ([#931](https://github.com/JosefPihrt/Roslynator/pull/931)).
+  - Required option: `roslynator_trailing_comma_style = include|omit|omit_when_single_line`
+  - Not enabled by default
 
 ### Changed
 

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

@@ -0,0 +1,139 @@
+// Copyright (c) Josef Pihrt and Contributors. Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Composition;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CodeActions;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Text;
+using Roslynator.CodeFixes;
+
+namespace Roslynator.CSharp.CodeFixes;
+
+[ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(AddOrRemoveTrailingCommaCodeFixProvider))]
+[Shared]
+public sealed class AddOrRemoveTrailingCommaCodeFixProvider : BaseCodeFixProvider
+{
+    public override ImmutableArray<string> FixableDiagnosticIds
+    {
+        get { return ImmutableArray.Create(DiagnosticIdentifiers.AddOrRemoveTrailingComma); }
+    }
+
+    public override async Task RegisterCodeFixesAsync(CodeFixContext context)
+    {
+        SyntaxNode root = await context.GetSyntaxRootAsync().ConfigureAwait(false);
+
+        if (!TryFindFirstAncestorOrSelf(
+            root,
+            context.Span,
+            out SyntaxNode node,
+            predicate: f => f.IsKind(
+                SyntaxKind.ArrayInitializerExpression,
+                SyntaxKind.ObjectInitializerExpression,
+                SyntaxKind.CollectionInitializerExpression,
+                SyntaxKind.EnumDeclaration,
+                SyntaxKind.AnonymousObjectCreationExpression)))
+        {
+            return;
+        }
+
+        Diagnostic diagnostic = context.Diagnostics[0];
+        Document document = context.Document;
+
+        if (node is InitializerExpressionSyntax initializer)
+        {
+            SeparatedSyntaxList<ExpressionSyntax> expressions = initializer.Expressions;
+
+            int count = expressions.Count;
+
+            if (count == expressions.SeparatorCount)
+            {
+                CodeAction codeAction = CodeAction.Create(
+                    "Remove comma",
+                    ct => RemoveTrailingComma(document, expressions.GetSeparator(count - 1), ct),
+                    GetEquivalenceKey(diagnostic));
+
+                context.RegisterCodeFix(codeAction, diagnostic);
+            }
+            else
+            {
+                CodeAction codeAction = CodeAction.Create(
+                    "Add comma",
+                    ct => AddTrailingComma(document, expressions.Last(), ct),
+                    GetEquivalenceKey(diagnostic));
+
+                context.RegisterCodeFix(codeAction, diagnostic);
+            }
+        }
+        else if (node is AnonymousObjectCreationExpressionSyntax objectCreation)
+        {
+            SeparatedSyntaxList<AnonymousObjectMemberDeclaratorSyntax> initializers = objectCreation.Initializers;
+
+            int count = initializers.Count;
+
+            if (count == initializers.SeparatorCount)
+            {
+                CodeAction codeAction = CodeAction.Create(
+                    "Remove comma",
+                    ct => RemoveTrailingComma(document, initializers.GetSeparator(count - 1), ct),
+                    GetEquivalenceKey(diagnostic));
+
+                context.RegisterCodeFix(codeAction, diagnostic);
+            }
+            else
+            {
+                CodeAction codeAction = CodeAction.Create(
+                    "Add comma",
+                    ct => AddTrailingComma(document, initializers.Last(), ct),
+                    GetEquivalenceKey(diagnostic));
+
+                context.RegisterCodeFix(codeAction, diagnostic);
+            }
+        }
+        else if (node is EnumDeclarationSyntax enumDeclaration)
+        {
+            SeparatedSyntaxList<EnumMemberDeclarationSyntax> members = enumDeclaration.Members;
+
+            int count = members.Count;
+
+            if (count == members.SeparatorCount)
+            {
+                CodeAction codeAction = CodeAction.Create(
+                    "Remove comma",
+                    ct => RemoveTrailingComma(document, members.GetSeparator(count - 1), ct),
+                    GetEquivalenceKey(diagnostic));
+
+                context.RegisterCodeFix(codeAction, diagnostic);
+            }
+            else
+            {
+                CodeAction codeAction = CodeAction.Create(
+                    "Add comma",
+                    ct => AddTrailingComma(document, members.Last(), ct),
+                    GetEquivalenceKey(diagnostic));
+
+                context.RegisterCodeFix(codeAction, diagnostic);
+            }
+        }
+    }
+
+    private static Task<Document> RemoveTrailingComma(
+        Document document,
+        SyntaxToken comma,
+        CancellationToken cancellationToken)
+    {
+        return document.WithTextChangeAsync(new TextChange(comma.Span, ""), cancellationToken);
+    }
+
+    private static Task<Document> AddTrailingComma(
+        Document document,
+        SyntaxNode lastNode,
+        CancellationToken cancellationToken)
+    {
+        return document.WithTextChangeAsync(new TextChange(new TextSpan(lastNode.Span.End, 0), ","), cancellationToken);
+    }
+}

src/Analyzers.xml

@@ -2336,10 +2336,13 @@ if (f)
   <Analyzer>
     <Id>RCS1035</Id>
     <Identifier>RemoveRedundantCommaInInitializer</Identifier>
+    <Status>Obsolete</Status>
+    <ObsoleteMessage>Use RCS1260 instead</ObsoleteMessage>
     <Title>Remove redundant comma in initializer.</Title>
     <DefaultSeverity>Hidden</DefaultSeverity>
     <IsEnabledByDefault>false</IsEnabledByDefault>
     <SupportsFadeOut>true</SupportsFadeOut>
+    <Tags>HideFromConfiguration</Tags>
     <Samples>
       <Sample>
         <Before><![CDATA[public void Foo()
@@ -7421,6 +7424,43 @@ void M()
   * empty region directive
 </Summary>
   </Analyzer>
+  <Analyzer Identifier="AddOrRemoveTrailingComma">
+    <Id>RCS1260</Id>
+    <Title>Add/remove trailing comma.</Title>
+    <MessageFormat>{0} trailing comma.</MessageFormat>
+    <Category>General</Category>
+    <DefaultSeverity>Info</DefaultSeverity>
+    <IsEnabledByDefault>false</IsEnabledByDefault>
+    <ConfigOptions>
+      <Option Key="trailing_comma_style" IsRequired="true" />
+    </ConfigOptions>
+    <Samples>
+      <Sample>
+        <ConfigOptions>
+          <Option Key="trailing_comma_style" Value="include" />
+        </ConfigOptions>
+        <Before><![CDATA[public enum Foo
+{
+    A,
+    B,
+    C
+}]]></Before>
+        <After><![CDATA[public enum Foo
+{
+    A,
+    B,
+    C,
+}]]></After>
+      </Sample>
+      <Sample>
+        <ConfigOptions>
+          <Option Key="trailing_comma_style" Value="omit_when_single_line" />
+        </ConfigOptions>
+        <Before><![CDATA[public enum Foo { A, B, C, }]]></Before>
+        <After><![CDATA[public enum Foo { A, B, C }]]></After>
+      </Sample>
+    </Samples>
+  </Analyzer>
   <Analyzer>
     <Id>RCS9001</Id>
     <Identifier>UsePatternMatching</Identifier>