Make more diagnostic analyzers into code style analyzers.

src/Features/CSharp/Portable/AddBraces/CSharpAddBracesDiagnosticAnalyzer.cs

 // 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.Immutable;
+using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Diagnostics;
 
 namespace Microsoft.CodeAnalysis.CSharp.Diagnostics.AddBraces
 {
     [DiagnosticAnalyzer(LanguageNames.CSharp)]
-    internal sealed class CSharpAddBracesDiagnosticAnalyzer : DiagnosticAnalyzer, IBuiltInAnalyzer
+    internal sealed class CSharpAddBracesDiagnosticAnalyzer : 
+        AbstractCodeStyleDiagnosticAnalyzer, IBuiltInAnalyzer
     {
         private static readonly LocalizableString s_localizableTitle =
             new LocalizableResourceString(nameof(FeaturesResources.Add_braces), FeaturesResources.ResourceManager,
@@ -17,14 +19,11 @@ internal sealed class CSharpAddBracesDiagnosticAnalyzer : DiagnosticAnalyzer, IB
             new LocalizableResourceString(nameof(WorkspacesResources.Add_braces_to_0_statement), WorkspacesResources.ResourceManager,
                 typeof(WorkspacesResources));
 
-        private static readonly DiagnosticDescriptor s_descriptor = new DiagnosticDescriptor(IDEDiagnosticIds.AddBracesDiagnosticId,
-                                                                    s_localizableTitle,
-                                                                    s_localizableMessage,
-                                                                    DiagnosticCategory.Style,
-                                                                    DiagnosticSeverity.Hidden,
-                                                                    isEnabledByDefault: true);
-
-        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } = ImmutableArray.Create(s_descriptor);
+        public CSharpAddBracesDiagnosticAnalyzer()
+            : base(IDEDiagnosticIds.AddBracesDiagnosticId,
+                   s_localizableTitle, s_localizableMessage)
+        {
+        }
 
         public bool OpenFileOnly(Workspace workspace) => false;
 
@@ -39,7 +38,8 @@ internal sealed class CSharpAddBracesDiagnosticAnalyzer : DiagnosticAnalyzer, IB
                 SyntaxKind.UsingStatement,
                 SyntaxKind.LockStatement);
 
-        public override void Initialize(AnalysisContext context)
+
+        protected override void InitializeWorker(AnalysisContext context)
             => context.RegisterSyntaxNodeAction(AnalyzeNode, s_syntaxKindsOfInterest);
 
         public DiagnosticAnalyzerCategory GetAnalyzerCategory() => DiagnosticAnalyzerCategory.SemanticSpanAnalysis;
@@ -53,7 +53,7 @@ public void AnalyzeNode(SyntaxNodeAnalysisContext context)
                 var ifStatement = (IfStatementSyntax)node;
                 if (AnalyzeIfStatement(ifStatement))
                 {
-                    context.ReportDiagnostic(Diagnostic.Create(s_descriptor,
+                    context.ReportDiagnostic(Diagnostic.Create(HiddenDescriptor,
                         ifStatement.IfKeyword.GetLocation(), SyntaxFacts.GetText(SyntaxKind.IfKeyword)));
                 }
             }
@@ -63,7 +63,7 @@ public void AnalyzeNode(SyntaxNodeAnalysisContext context)
                 var elseClause = (ElseClauseSyntax)node;
                 if (AnalyzeElseClause(elseClause))
                 {
-                    context.ReportDiagnostic(Diagnostic.Create(s_descriptor,
+                    context.ReportDiagnostic(Diagnostic.Create(HiddenDescriptor,
                         elseClause.ElseKeyword.GetLocation(), SyntaxFacts.GetText(SyntaxKind.ElseKeyword)));
                 }
             }
@@ -73,7 +73,7 @@ public void AnalyzeNode(SyntaxNodeAnalysisContext context)
                 var forStatement = (ForStatementSyntax)node;
                 if (AnalyzeForStatement(forStatement))
                 {
-                    context.ReportDiagnostic(Diagnostic.Create(s_descriptor,
+                    context.ReportDiagnostic(Diagnostic.Create(HiddenDescriptor,
                         forStatement.ForKeyword.GetLocation(), SyntaxFacts.GetText(SyntaxKind.ForKeyword)));
                 }
             }
@@ -83,7 +83,7 @@ public void AnalyzeNode(SyntaxNodeAnalysisContext context)
                 var forEachStatement = (CommonForEachStatementSyntax)node;
                 if (AnalyzeForEachStatement(forEachStatement))
                 {
-                    context.ReportDiagnostic(Diagnostic.Create(s_descriptor,
+                    context.ReportDiagnostic(Diagnostic.Create(HiddenDescriptor,
                         forEachStatement.ForEachKeyword.GetLocation(), SyntaxFacts.GetText(SyntaxKind.ForEachKeyword)));
                 }
             }
@@ -93,7 +93,7 @@ public void AnalyzeNode(SyntaxNodeAnalysisContext context)
                 var whileStatement = (WhileStatementSyntax)node;
                 if (AnalyzeWhileStatement(whileStatement))
                 {
-                    context.ReportDiagnostic(Diagnostic.Create(s_descriptor,
+                    context.ReportDiagnostic(Diagnostic.Create(HiddenDescriptor,
                         whileStatement.WhileKeyword.GetLocation(), SyntaxFacts.GetText(SyntaxKind.WhileKeyword)));
                 }
             }
@@ -103,7 +103,7 @@ public void AnalyzeNode(SyntaxNodeAnalysisContext context)
                 var doStatement = (DoStatementSyntax)node;
                 if (AnalyzeDoStatement(doStatement))
                 {
-                    context.ReportDiagnostic(Diagnostic.Create(s_descriptor,
+                    context.ReportDiagnostic(Diagnostic.Create(HiddenDescriptor,
                         doStatement.DoKeyword.GetLocation(), SyntaxFacts.GetText(SyntaxKind.DoKeyword)));
                 }
             }
@@ -113,7 +113,7 @@ public void AnalyzeNode(SyntaxNodeAnalysisContext context)
                 var usingStatement = (UsingStatementSyntax)context.Node;
                 if (AnalyzeUsingStatement(usingStatement))
                 {
-                    context.ReportDiagnostic(Diagnostic.Create(s_descriptor,
+                    context.ReportDiagnostic(Diagnostic.Create(HiddenDescriptor,
                         usingStatement.UsingKeyword.GetLocation(), SyntaxFacts.GetText(SyntaxKind.UsingKeyword)));
                 }
             }
@@ -123,7 +123,7 @@ public void AnalyzeNode(SyntaxNodeAnalysisContext context)
                 var lockStatement = (LockStatementSyntax)context.Node;
                 if (AnalyzeLockStatement(lockStatement))
                 {
-                    context.ReportDiagnostic(Diagnostic.Create(s_descriptor,
+                    context.ReportDiagnostic(Diagnostic.Create(HiddenDescriptor,
                         lockStatement.LockKeyword.GetLocation(), SyntaxFacts.GetText(SyntaxKind.LockKeyword)));
                 }
             }

src/Features/Core/Portable/CodeStyle/AbstractCodeStyleDiagnosticAnalyzer.cs

@@ -9,6 +9,11 @@ internal abstract class AbstractCodeStyleDiagnosticAnalyzer : DiagnosticAnalyzer
     {
         protected readonly string DescriptorId;
 
+        /// <summary>
+        /// Diagnostic descriptor that for analysis results that we don't want any treatment for.
+        /// </summary>
+        protected readonly DiagnosticDescriptor HiddenDescriptor;
+
         /// <summary>
         /// Diagnostic descriptor for code you want to fade out *and* want to have a smart-tag
         /// appear for.  This is the common descriptor for code that is being faded out
@@ -39,7 +44,7 @@ internal abstract class AbstractCodeStyleDiagnosticAnalyzer : DiagnosticAnalyzer
             _localizableTitle = title;
             _localizableMessage = message ?? title;
 
-            var primaryDescriptor = CreateDescriptorWithSeverity(DiagnosticSeverity.Hidden);
+            HiddenDescriptor = CreateDescriptorWithSeverity(DiagnosticSeverity.Hidden);
 
             UnnecessaryWithSuggestionDescriptor = CreateDescriptorWithId(
                 descriptorId, _localizableTitle, _localizableMessage, 
@@ -51,7 +56,7 @@ internal abstract class AbstractCodeStyleDiagnosticAnalyzer : DiagnosticAnalyzer
                 DiagnosticSeverity.Hidden, DiagnosticCustomTags.Unnecessary);
 
             SupportedDiagnostics = ImmutableArray.Create(
-                primaryDescriptor, UnnecessaryWithoutSuggestionDescriptor, UnnecessaryWithSuggestionDescriptor);
+                HiddenDescriptor, UnnecessaryWithoutSuggestionDescriptor, UnnecessaryWithSuggestionDescriptor);
         }
 
         public sealed override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; }

src/Features/Core/Portable/Diagnostics/Analyzers/IDEDiagnosticIds.cs

@@ -40,6 +40,8 @@ internal static class IDEDiagnosticIds
 
         public const string UseNullPropagationDiagnosticId = "IDE0030";
 
+        public const string UseAutoPropertyDiagnosticId = "IDE0031";
+
         // Analyzer error Ids
         public const string AnalyzerChangedId = "IDE1001";
         public const string AnalyzerDependencyConflictId = "IDE1002";

src/Features/Core/Portable/PopulateSwitch/PopulateSwitchDiagnosticAnalyzer.cs

@@ -4,6 +4,7 @@
 using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Reflection;
+using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Semantics;
 using Microsoft.CodeAnalysis.Shared.Extensions;
@@ -11,26 +12,25 @@
 namespace Microsoft.CodeAnalysis.PopulateSwitch
 {
     [DiagnosticAnalyzer(LanguageNames.CSharp, LanguageNames.VisualBasic)]
-    internal sealed class PopulateSwitchDiagnosticAnalyzer : DiagnosticAnalyzer, IBuiltInAnalyzer
+    internal sealed class PopulateSwitchDiagnosticAnalyzer : 
+        AbstractCodeStyleDiagnosticAnalyzer, IBuiltInAnalyzer
     {
         private static readonly LocalizableString s_localizableTitle = new LocalizableResourceString(nameof(FeaturesResources.Add_missing_cases), FeaturesResources.ResourceManager, typeof(FeaturesResources));
         private static readonly LocalizableString s_localizableMessage = new LocalizableResourceString(nameof(WorkspacesResources.Populate_switch), WorkspacesResources.ResourceManager, typeof(WorkspacesResources));
 
-        private static readonly DiagnosticDescriptor s_descriptor = new DiagnosticDescriptor(IDEDiagnosticIds.PopulateSwitchDiagnosticId,
-            s_localizableTitle,
-            s_localizableMessage,
-            DiagnosticCategory.Style,
-            DiagnosticSeverity.Hidden,
-            isEnabledByDefault: true);
+        public PopulateSwitchDiagnosticAnalyzer()
+            : base(IDEDiagnosticIds.PopulateSwitchDiagnosticId,
+                  s_localizableTitle, s_localizableMessage)
+        {
+        }
 
         #region Interface methods
 
-        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(s_descriptor);
         public bool OpenFileOnly(Workspace workspace) => false;
 
         private static MethodInfo s_registerMethod = typeof(AnalysisContext).GetTypeInfo().GetDeclaredMethod("RegisterOperationActionImmutableArrayInternal");
 
-        public override void Initialize(AnalysisContext context)
+        protected override void InitializeWorker(AnalysisContext context)
             => s_registerMethod.Invoke(context, new object[]
                {
                    new Action<OperationAnalysisContext>(AnalyzeOperation),
@@ -54,7 +54,7 @@ private void AnalyzeOperation(OperationAnalysisContext context)
                     .Add(PopulateSwitchHelpers.MissingDefaultCase, missingDefaultCase.ToString());
 
                 var diagnostic = Diagnostic.Create(
-                    s_descriptor, switchBlock.GetLocation(), properties: properties);
+                    HiddenDescriptor, switchBlock.GetLocation(), properties: properties);
                 context.ReportDiagnostic(diagnostic);
             }
         }

src/Features/Core/Portable/UseAutoProperty/AbstractUseAutoPropertyAnalyzer.cs

@@ -4,29 +4,34 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Threading;
+using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.Diagnostics;
 
 namespace Microsoft.CodeAnalysis.UseAutoProperty
 {
-    internal abstract class AbstractUseAutoPropertyAnalyzer<TPropertyDeclaration, TFieldDeclaration, TVariableDeclarator, TExpression> : DiagnosticAnalyzer
+    internal abstract class AbstractUseAutoPropertyAnalyzer<TPropertyDeclaration, TFieldDeclaration, TVariableDeclarator, TExpression> : 
+        AbstractCodeStyleDiagnosticAnalyzer
         where TPropertyDeclaration : SyntaxNode
         where TFieldDeclaration : SyntaxNode
         where TVariableDeclarator : SyntaxNode
         where TExpression : SyntaxNode
     {
-        public const string UseAutoProperty = nameof(UseAutoProperty);
-        public const string UseAutoPropertyFadedToken = nameof(UseAutoPropertyFadedToken);
+        private static readonly LocalizableString s_title =
+            new LocalizableResourceString(nameof(FeaturesResources.Use_auto_property), FeaturesResources.ResourceManager, typeof(FeaturesResources));
 
-        private readonly static DiagnosticDescriptor s_descriptor = new DiagnosticDescriptor(
-            UseAutoProperty, FeaturesResources.Use_auto_property, FeaturesResources.Use_auto_property,
-            "Language", DiagnosticSeverity.Hidden, isEnabledByDefault: true);
+        protected AbstractUseAutoPropertyAnalyzer()
+            : base(IDEDiagnosticIds.UseAutoPropertyDiagnosticId, s_title, s_title)
+        {
+        }
 
-        private readonly static DiagnosticDescriptor s_fadedTokenDescriptor = new DiagnosticDescriptor(
-            UseAutoPropertyFadedToken, FeaturesResources.Use_auto_property, FeaturesResources.Use_auto_property,
-            "Language", DiagnosticSeverity.Hidden, isEnabledByDefault: true,
-            customTags: new[] { WellKnownDiagnosticTags.Unnecessary });
+        //private readonly static DiagnosticDescriptor s_descriptor = new DiagnosticDescriptor(
+        //    UseAutoProperty, FeaturesResources.Use_auto_property, FeaturesResources.Use_auto_property,
+        //    "Language", DiagnosticSeverity.Hidden, isEnabledByDefault: true);
 
-        public sealed override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(s_descriptor, s_fadedTokenDescriptor);
+        //private readonly static DiagnosticDescriptor s_fadedTokenDescriptor = new DiagnosticDescriptor(
+        //    UseAutoPropertyFadedToken, FeaturesResources.Use_auto_property, FeaturesResources.Use_auto_property,
+        //    "Language", DiagnosticSeverity.Hidden, isEnabledByDefault: true,
+        //    customTags: new[] { WellKnownDiagnosticTags.Unnecessary });
 
         protected abstract void RegisterIneligibleFieldsAction(CompilationStartAnalysisContext context, ConcurrentBag<IFieldSymbol> ineligibleFields);
         protected abstract bool SupportsReadOnlyProperties(Compilation compilation);
@@ -36,7 +41,7 @@ internal abstract class AbstractUseAutoPropertyAnalyzer<TPropertyDeclaration, TF
         protected abstract TExpression GetSetterExpression(IMethodSymbol setMethod, SemanticModel semanticModel, CancellationToken cancellationToken);
         protected abstract SyntaxNode GetNodeToFade(TFieldDeclaration fieldDeclaration, TVariableDeclarator variableDeclarator);
 
-        public sealed override void Initialize(AnalysisContext context)
+        protected sealed override void InitializeWorker(AnalysisContext context)
             => context.RegisterCompilationStartAction(csac =>
                {
                    var analysisResults = new ConcurrentBag<AnalysisResult>();
@@ -251,7 +256,7 @@ private void Process(AnalysisResult result, CompilationAnalysisContext compilati
             var properties = ImmutableDictionary<string, string>.Empty.Add(nameof(result.SymbolEquivalenceKey), result.SymbolEquivalenceKey);
 
             // Fade out the field/variable we are going to remove.
-            var diagnostic1 = Diagnostic.Create(s_fadedTokenDescriptor, nodeToFade.GetLocation());
+            var diagnostic1 = Diagnostic.Create(UnnecessaryWithSuggestionDescriptor, nodeToFade.GetLocation());
             compilationContext.ReportDiagnostic(diagnostic1);
 
             // Now add diagnostics to both the field and the property saying we can convert it to 
@@ -259,10 +264,10 @@ private void Process(AnalysisResult result, CompilationAnalysisContext compilati
             // them when performing the code fix.
             IEnumerable<Location> additionalLocations = new Location[] { propertyDeclaration.GetLocation(), variableDeclarator.GetLocation() };
 
-            var diagnostic2 = Diagnostic.Create(s_descriptor, propertyDeclaration.GetLocation(), additionalLocations, properties);
+            var diagnostic2 = Diagnostic.Create(HiddenDescriptor, propertyDeclaration.GetLocation(), additionalLocations, properties);
             compilationContext.ReportDiagnostic(diagnostic2);
 
-            var diagnostic3 = Diagnostic.Create(s_descriptor, nodeToFade.GetLocation(), additionalLocations, properties);
+            var diagnostic3 = Diagnostic.Create(HiddenDescriptor, nodeToFade.GetLocation(), additionalLocations, properties);
             compilationContext.ReportDiagnostic(diagnostic3);
         }
 
@@ -297,4 +302,4 @@ internal class AnalysisResult
             }
         }
     }
-}
+}
\ No newline at end of file

src/Features/Core/Portable/UseAutoProperty/AbstractUseAutoPropertyCodeFixProvider.cs

@@ -9,6 +9,7 @@
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CodeActions;
 using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Editing;
 using Microsoft.CodeAnalysis.FindSymbols;
 using Microsoft.CodeAnalysis.Formatting;
@@ -28,8 +29,8 @@ internal abstract class AbstractUseAutoPropertyCodeFixProvider<TPropertyDeclarat
     {
         protected static SyntaxAnnotation SpecializedFormattingAnnotation = new SyntaxAnnotation();
 
-        public sealed override ImmutableArray<string> FixableDiagnosticIds => ImmutableArray.Create(
-            AbstractUseAutoPropertyAnalyzer<TPropertyDeclaration, TFieldDeclaration, TVariableDeclarator, TExpression>.UseAutoProperty);
+        public sealed override ImmutableArray<string> FixableDiagnosticIds 
+            => ImmutableArray.Create(IDEDiagnosticIds.UseAutoPropertyDiagnosticId);
 
         public sealed override FixAllProvider GetFixAllProvider() => WellKnownFixAllProviders.BatchFixer;