RS0046: Avoid Opt suffix in nullable-enabled code

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

@@ -0,0 +1,26 @@
+// 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.Collections.Generic;
+using System.Linq;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Roslyn.Diagnostics.Analyzers;
+
+namespace Roslyn.Diagnostics.CSharp.Analyzers
+{
+    [DiagnosticAnalyzer(LanguageNames.CSharp)]
+    public sealed class CSharpAvoidOptSuffixForNullableEnableCode : AvoidOptSuffixForNullableEnableCode
+    {
+        protected override bool IsNullableEnabledContext(CompilationOptions compilationOptions, IEnumerable<ParseOptions?> parseOptions)
+        {
+            var hasAnyCSharp8Part = parseOptions.OfType<CSharpParseOptions>().Any(option => option.LanguageVersion >= LanguageVersion.CSharp8);
+
+            return hasAnyCSharp8Part && IsNullableEnabledContext(compilationOptions);
+        }
+
+        private static bool IsNullableEnabledContext(CompilationOptions compilationOptions)
+            => compilationOptions is CSharpCompilationOptions csharpCompilationOptions &&
+                csharpCompilationOptions.NullableContextOptions == NullableContextOptions.Enable;
+    }
+}

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

@@ -0,0 +1,55 @@
+// 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.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+using Analyzer.Utilities;
+using Analyzer.Utilities.Extensions;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace Roslyn.Diagnostics.Analyzers
+{
+    public abstract class AvoidOptSuffixForNullableEnableCode : DiagnosticAnalyzer
+    {
+        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: false,
+            description: s_localizableDescription,
+            helpLinkUri: null,
+            customTags: WellKnownDiagnosticTags.Telemetry);
+
+        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Rule);
+
+        public sealed override void Initialize(AnalysisContext context)
+        {
+            context.EnableConcurrentExecution();
+            context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+
+            context.RegisterSymbolAction(context =>
+            {
+                if (context.Symbol.Name.EndsWith("Opt", System.StringComparison.Ordinal))
+                {
+                    var parseOptions = context.Symbol.DeclaringSyntaxReferences
+                        .Select(syntaxRef => syntaxRef.GetSyntax(context.CancellationToken)?.SyntaxTree?.Options);
+
+                    if (IsNullableEnabledContext(context.Compilation.Options, parseOptions))
+                    {
+                        context.ReportDiagnostic(context.Symbol.CreateDiagnostic(Rule));
+                    }
+                }
+            }, SymbolKind.Parameter, SymbolKind.Field);
+        }
+
+        protected abstract bool IsNullableEnabledContext(CompilationOptions compilationOptions, IEnumerable<ParseOptions?> parseOptions);
+    }
+}

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

@@ -41,5 +41,6 @@ internal static class RoslynDiagnosticIds
         public const string RestrictedInternalsVisibleToRuleId = "RS0035";
         public const string AnnotatePublicApiRuleId = "RS0036";
         public const string ShouldAnnotateApiFilesRuleId = "RS0037";
+        public const string AvoidOptSuffixForNullableEnableCodeRuleId = "RS0037";
     }
 }

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

@@ -255,4 +255,13 @@
   <data name="FixNumberedComments" xml:space="preserve">
     <value>Fix numbered comments</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>
 </root>

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

@@ -2,6 +2,21 @@
 <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="ExportedPartsShouldHaveImportingConstructorCodeFix_ImplicitConstructor">
         <source>Explicitly define the importing constructor</source>
         <target state="translated">Explicitně definujte importující konstruktor.</target>

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

@@ -2,6 +2,21 @@
 <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="ExportedPartsShouldHaveImportingConstructorCodeFix_ImplicitConstructor">
         <source>Explicitly define the importing constructor</source>
         <target state="translated">Importierenden Konstruktor explizit definieren</target>

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

@@ -2,6 +2,21 @@
 <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="ExportedPartsShouldHaveImportingConstructorCodeFix_ImplicitConstructor">
         <source>Explicitly define the importing constructor</source>
         <target state="translated">Definir explícitamente el constructor de importación</target>

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

@@ -2,6 +2,21 @@
 <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="ExportedPartsShouldHaveImportingConstructorCodeFix_ImplicitConstructor">
         <source>Explicitly define the importing constructor</source>
         <target state="translated">Définir explicitement le constructeur d'importation</target>

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

@@ -2,6 +2,21 @@
 <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="ExportedPartsShouldHaveImportingConstructorCodeFix_ImplicitConstructor">
         <source>Explicitly define the importing constructor</source>
         <target state="translated">Definire esplicitamente il costruttore di importazione</target>

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

@@ -2,6 +2,21 @@
 <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="ExportedPartsShouldHaveImportingConstructorCodeFix_ImplicitConstructor">
         <source>Explicitly define the importing constructor</source>
         <target state="translated">インポート コンストラクターを明示的に定義します</target>

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

@@ -2,6 +2,21 @@
 <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="ExportedPartsShouldHaveImportingConstructorCodeFix_ImplicitConstructor">
         <source>Explicitly define the importing constructor</source>
         <target state="translated">명시적으로 가져오기 생성자 정의</target>

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

@@ -2,6 +2,21 @@
 <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="pl" 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="ExportedPartsShouldHaveImportingConstructorCodeFix_ImplicitConstructor">
         <source>Explicitly define the importing constructor</source>
         <target state="translated">Jawnie zdefiniuj konstruktor importujący</target>

src/Roslyn.Diagnostics.Analyzers/Core/xlf/RoslynDiagnosticsAnalyzersResources.pt-BR.xlf

@@ -2,6 +2,21 @@
 <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="pt-BR" 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="ExportedPartsShouldHaveImportingConstructorCodeFix_ImplicitConstructor">
         <source>Explicitly define the importing constructor</source>
         <target state="translated">Definir explicitamente o construtor de importação</target>

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

@@ -2,6 +2,21 @@
 <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="ru" 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="ExportedPartsShouldHaveImportingConstructorCodeFix_ImplicitConstructor">
         <source>Explicitly define the importing constructor</source>
         <target state="translated">Явно определите конструктор импорта.</target>