RS0046: Avoid Opt suffix in nullable-enabled code

src/Roslyn.Diagnostics.Analyzers/CSharp/AnalyzerReleases.Unshipped.md

@@ -2,5 +2,6 @@
 Rule ID | Category | Severity | Notes
 --------|----------|----------|-------
 RS0038 | RoslynDiagnosticsMaintainability | Warning | PreferNullLiteral
+RS0046 | RoslynDiagnosticsDesign | Warning | CSharpAvoidOptSuffixForNullableEnableCode
 RS0100 | RoslynDiagnosticsMaintainability | Warning | CSharpWrapStatementsDiagnosticAnalyzer
 RS0102 | RoslynDiagnosticsMaintainability | Warning | CSharpBracePlacementDiagnosticAnalyzer

src/Roslyn.Diagnostics.Analyzers/CSharp/CSharpAvoidOptSuffixForNullableEnableCode.cs

@@ -0,0 +1,68 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Immutable;
+using Analyzer.Utilities;
+using Analyzer.Utilities.Extensions;
+using Analyzer.Utilities.Lightup;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Roslyn.Diagnostics.Analyzers;
+
+namespace Roslyn.Diagnostics.CSharp.Analyzers
+{
+    /// <summary>
+    /// RS0046: Avoid 'Opt' suffix for nullable enable code
+    /// </summary>
+    [DiagnosticAnalyzer(LanguageNames.CSharp)]
+    public sealed class CSharpAvoidOptSuffixForNullableEnableCode : DiagnosticAnalyzer
+    {
+        internal const string OptSuffix = "Opt";
+
+        private static readonly LocalizableString s_localizableTitle = new LocalizableResourceString(nameof(RoslynDiagnosticsAnalyzersResources.AvoidOptSuffixForNullableEnableCodeRuleIdTitle), RoslynDiagnosticsAnalyzersResources.ResourceManager, typeof(RoslynDiagnosticsAnalyzersResources));
+        private static readonly LocalizableString s_localizableMessage = new LocalizableResourceString(nameof(RoslynDiagnosticsAnalyzersResources.AvoidOptSuffixForNullableEnableCodeRuleIdMessage), RoslynDiagnosticsAnalyzersResources.ResourceManager, typeof(RoslynDiagnosticsAnalyzersResources));
+        private static readonly LocalizableString s_localizableDescription = new LocalizableResourceString(nameof(RoslynDiagnosticsAnalyzersResources.AvoidOptSuffixForNullableEnableCodeRuleIdDescription), RoslynDiagnosticsAnalyzersResources.ResourceManager, typeof(RoslynDiagnosticsAnalyzersResources));
+
+        internal static DiagnosticDescriptor Rule = new DiagnosticDescriptor(
+            RoslynDiagnosticIds.AvoidOptSuffixForNullableEnableCodeRuleId,
+            s_localizableTitle,
+            s_localizableMessage,
+            DiagnosticCategory.RoslynDiagnosticsDesign,
+            DiagnosticSeverity.Warning,
+            isEnabledByDefault: true,
+            description: s_localizableDescription,
+            helpLinkUri: null,
+            customTags: WellKnownDiagnosticTags.Telemetry);
+
+        public sealed override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Rule);
+
+        public override void Initialize(AnalysisContext context)
+        {
+            context.EnableConcurrentExecution();
+            context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+
+            context.RegisterSyntaxNodeAction(context =>
+            {
+                var parameter = (ParameterSyntax)context.Node;
+                ReportOnInvalidIdentifier(parameter.Identifier, context.SemanticModel, context.ReportDiagnostic);
+            }, SyntaxKind.Parameter);
+
+            context.RegisterSyntaxNodeAction(context =>
+            {
+                var variableDeclarator = (VariableDeclaratorSyntax)context.Node;
+                ReportOnInvalidIdentifier(variableDeclarator.Identifier, context.SemanticModel, context.ReportDiagnostic);
+            }, SyntaxKind.VariableDeclarator);
+        }
+
+        private static void ReportOnInvalidIdentifier(SyntaxToken identifier, SemanticModel semanticModel, Action<Diagnostic> reportAction)
+        {
+            if (identifier.Text.EndsWith(OptSuffix, StringComparison.Ordinal) &&
+                semanticModel.GetNullableContext(identifier.SpanStart).AnnotationsEnabled())
+            {
+                reportAction(identifier.CreateDiagnostic(Rule));
+            }
+        }
+    }
+}

src/Roslyn.Diagnostics.Analyzers/CSharp/CSharpAvoidOptSuffixForNullableEnableCodeCodeFixProvider.cs

@@ -0,0 +1,82 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Immutable;
+using System.Composition;
+using System.Threading;
+using System.Threading.Tasks;
+using Analyzer.Utilities;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.Rename;
+using Roslyn.Diagnostics.Analyzers;
+
+namespace Roslyn.Diagnostics.CSharp.Analyzers
+{
+    [ExportCodeFixProvider(LanguageNames.CSharp)]
+    [Shared]
+    public sealed class CSharpAvoidOptSuffixForNullableEnableCodeCodeFixProvider : CodeFixProvider
+    {
+        public override ImmutableArray<string> FixableDiagnosticIds => ImmutableArray.Create(CSharpAvoidOptSuffixForNullableEnableCode.Rule.Id);
+
+        public override FixAllProvider GetFixAllProvider()
+            => WellKnownFixAllProviders.BatchFixer;
+
+        public override async Task RegisterCodeFixesAsync(CodeFixContext context)
+        {
+            var title = RoslynDiagnosticsAnalyzersResources.AvoidOptSuffixForNullableEnableCodeRuleIdTitleCodeFixTitle;
+
+            foreach (var diagnostic in context.Diagnostics)
+            {
+                var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+                if (root == null)
+                {
+                    continue;
+                }
+
+                var variable = root.FindNode(diagnostic.Location.SourceSpan, getInnermostNodeForTie: true);
+                if (variable == null)
+                {
+                    continue;
+                }
+
+                var semanticModel = await context.Document.GetSemanticModelAsync(context.CancellationToken).ConfigureAwait(false);
+                var variableSymbol = semanticModel.GetDeclaredSymbol(variable, context.CancellationToken);
+                if (variableSymbol == null)
+                {
+                    continue;
+                }
+
+                var newName = variableSymbol.Name.Substring(0, variableSymbol.Name.Length - CSharpAvoidOptSuffixForNullableEnableCode.OptSuffix.Length);
+
+                // There is no symbol matching the new name so we can register the codefix
+                if (semanticModel.LookupSymbols(diagnostic.Location.SourceSpan.Start, variableSymbol.ContainingType, newName).IsEmpty)
+                {
+                    context.RegisterCodeFix(
+                        new MyCodeAction(
+                            title,
+                            cancellationToken => RemoveOptSuffixOnVariableAsync(context.Document, variableSymbol, newName, cancellationToken),
+                            equivalenceKey: title),
+                        diagnostic);
+                }
+            }
+        }
+
+        private static async Task<Document> RemoveOptSuffixOnVariableAsync(Document document, ISymbol variableSymbol, string newName, CancellationToken cancellationToken)
+        {
+            var newSolution = await Renamer.RenameSymbolAsync(document.Project.Solution, variableSymbol, newName, document.Project.Solution.Options, cancellationToken)
+                .ConfigureAwait(false);
+
+            return newSolution.GetDocument(document.Id)!;
+        }
+
+        // Needed for Telemetry (https://github.com/dotnet/roslyn/issues/4919)
+        private class MyCodeAction : DocumentChangeAction
+        {
+            public MyCodeAction(string title, Func<CancellationToken, Task<Document>> createChangedDocument, string equivalenceKey)
+                : base(title, createChangedDocument, equivalenceKey)
+            {
+            }
+        }
+    }
+}

src/Roslyn.Diagnostics.Analyzers/Core/RoslynDiagnosticIds.cs

@@ -49,6 +49,7 @@ internal static class RoslynDiagnosticIds
         public const string DoNotCallGetTestAccessorRuleId = "RS0043";
         public const string CreateTestAccessorRuleId = "RS0044";
         public const string ExposeMemberForTestingRuleId = "RS0045";
+        public const string AvoidOptSuffixForNullableEnableCodeRuleId = "RS0046";
 
         public const string WrapStatementsRuleId = "RS0100";
         public const string BlankLinesRuleId = "RS0101";

src/Roslyn.Diagnostics.Analyzers/Core/RoslynDiagnosticsAnalyzersResources.resx

@@ -339,6 +339,15 @@
   <data name="ExposeMemberForTestingTitle" xml:space="preserve">
     <value>Expose member for testing</value>
   </data>
+  <data name="AvoidOptSuffixForNullableEnableCodeRuleIdDescription" xml:space="preserve">
+    <value>Avoid the 'Opt' suffix in a nullable-enabled code.</value>
+  </data>
+  <data name="AvoidOptSuffixForNullableEnableCodeRuleIdMessage" xml:space="preserve">
+    <value>Avoid the 'Opt' suffix in a nullable-enabled code</value>
+  </data>
+  <data name="AvoidOptSuffixForNullableEnableCodeRuleIdTitle" xml:space="preserve">
+    <value>Avoid the 'Opt' suffix</value>
+  </data>
   <data name="BracePlacementMessage" xml:space="preserve">
     <value>Braces must not have blank lines between them</value>
   </data>
@@ -357,4 +366,7 @@
   <data name="Place_statement_on_following_line" xml:space="preserve">
     <value>Place statement on following line</value>
   </data>
+  <data name="AvoidOptSuffixForNullableEnableCodeRuleIdTitleCodeFixTitle" xml:space="preserve">
+    <value>Remove the 'Opt' suffix</value>
+  </data>
 </root>

src/Roslyn.Diagnostics.Analyzers/Core/xlf/RoslynDiagnosticsAnalyzersResources.cs.xlf

@@ -2,6 +2,26 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="cs" original="../RoslynDiagnosticsAnalyzersResources.resx">
     <body>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdDescription">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code.</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdMessage">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitle">
+        <source>Avoid the 'Opt' suffix</source>
+        <target state="new">Avoid the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitleCodeFixTitle">
+        <source>Remove the 'Opt' suffix</source>
+        <target state="new">Remove the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
       <trans-unit id="BlankLinesMessage">
         <source>Avoid multiple blank lines</source>
         <target state="new">Avoid multiple blank lines</target>

src/Roslyn.Diagnostics.Analyzers/Core/xlf/RoslynDiagnosticsAnalyzersResources.de.xlf

@@ -2,6 +2,26 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="de" original="../RoslynDiagnosticsAnalyzersResources.resx">
     <body>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdDescription">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code.</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdMessage">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitle">
+        <source>Avoid the 'Opt' suffix</source>
+        <target state="new">Avoid the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitleCodeFixTitle">
+        <source>Remove the 'Opt' suffix</source>
+        <target state="new">Remove the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
       <trans-unit id="BlankLinesMessage">
         <source>Avoid multiple blank lines</source>
         <target state="new">Avoid multiple blank lines</target>

src/Roslyn.Diagnostics.Analyzers/Core/xlf/RoslynDiagnosticsAnalyzersResources.es.xlf

@@ -2,6 +2,26 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="es" original="../RoslynDiagnosticsAnalyzersResources.resx">
     <body>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdDescription">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code.</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdMessage">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitle">
+        <source>Avoid the 'Opt' suffix</source>
+        <target state="new">Avoid the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitleCodeFixTitle">
+        <source>Remove the 'Opt' suffix</source>
+        <target state="new">Remove the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
       <trans-unit id="BlankLinesMessage">
         <source>Avoid multiple blank lines</source>
         <target state="new">Avoid multiple blank lines</target>

src/Roslyn.Diagnostics.Analyzers/Core/xlf/RoslynDiagnosticsAnalyzersResources.fr.xlf

@@ -2,6 +2,26 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="fr" original="../RoslynDiagnosticsAnalyzersResources.resx">
     <body>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdDescription">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code.</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdMessage">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitle">
+        <source>Avoid the 'Opt' suffix</source>
+        <target state="new">Avoid the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitleCodeFixTitle">
+        <source>Remove the 'Opt' suffix</source>
+        <target state="new">Remove the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
       <trans-unit id="BlankLinesMessage">
         <source>Avoid multiple blank lines</source>
         <target state="new">Avoid multiple blank lines</target>

src/Roslyn.Diagnostics.Analyzers/Core/xlf/RoslynDiagnosticsAnalyzersResources.it.xlf

@@ -2,6 +2,26 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="it" original="../RoslynDiagnosticsAnalyzersResources.resx">
     <body>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdDescription">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code.</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdMessage">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitle">
+        <source>Avoid the 'Opt' suffix</source>
+        <target state="new">Avoid the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitleCodeFixTitle">
+        <source>Remove the 'Opt' suffix</source>
+        <target state="new">Remove the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
       <trans-unit id="BlankLinesMessage">
         <source>Avoid multiple blank lines</source>
         <target state="new">Avoid multiple blank lines</target>

src/Roslyn.Diagnostics.Analyzers/Core/xlf/RoslynDiagnosticsAnalyzersResources.ja.xlf

@@ -2,6 +2,26 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="ja" original="../RoslynDiagnosticsAnalyzersResources.resx">
     <body>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdDescription">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code.</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdMessage">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitle">
+        <source>Avoid the 'Opt' suffix</source>
+        <target state="new">Avoid the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitleCodeFixTitle">
+        <source>Remove the 'Opt' suffix</source>
+        <target state="new">Remove the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
       <trans-unit id="BlankLinesMessage">
         <source>Avoid multiple blank lines</source>
         <target state="new">Avoid multiple blank lines</target>

src/Roslyn.Diagnostics.Analyzers/Core/xlf/RoslynDiagnosticsAnalyzersResources.ko.xlf

@@ -2,6 +2,26 @@
 <xliff xmlns="urn:oasis:names:tc:xliff:document:1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.2" xsi:schemaLocation="urn:oasis:names:tc:xliff:document:1.2 xliff-core-1.2-transitional.xsd">
   <file datatype="xml" source-language="en" target-language="ko" original="../RoslynDiagnosticsAnalyzersResources.resx">
     <body>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdDescription">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code.</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdMessage">
+        <source>Avoid the 'Opt' suffix in a nullable-enabled code</source>
+        <target state="new">Avoid the 'Opt' suffix in a nullable-enabled code</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitle">
+        <source>Avoid the 'Opt' suffix</source>
+        <target state="new">Avoid the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="AvoidOptSuffixForNullableEnableCodeRuleIdTitleCodeFixTitle">
+        <source>Remove the 'Opt' suffix</source>
+        <target state="new">Remove the 'Opt' suffix</target>
+        <note />
+      </trans-unit>
       <trans-unit id="BlankLinesMessage">
         <source>Avoid multiple blank lines</source>
         <target state="new">Avoid multiple blank lines</target>