Delete the public TriggerDiagnosticDescriptor type.

src/Compilers/CSharp/Test/Semantic/Diagnostics/DiagnosticAnalyzerTests.cs

@@ -3,10 +3,8 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
-using System.Globalization;
 using System.Linq;
 using System.Runtime.Serialization;
-using System.Threading;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.CSharp.Test.Utilities;
 using Microsoft.CodeAnalysis.Diagnostics;
@@ -841,12 +839,12 @@ public class CodeBlockOrSyntaxNodeAnalyzer : DiagnosticAnalyzer
         {
             private readonly bool _isCodeBlockAnalyzer;
 
-            public static DiagnosticDescriptor Desciptor1 = new TriggerDiagnosticDescriptor("CodeBlockDiagnostic");
-            public static DiagnosticDescriptor Desciptor2 = new TriggerDiagnosticDescriptor("EqualsValueDiagnostic");
-            public static DiagnosticDescriptor Desciptor3 = new TriggerDiagnosticDescriptor("ConstructorInitializerDiagnostic");
-            public static DiagnosticDescriptor Desciptor4 = new TriggerDiagnosticDescriptor("PropertyExpressionBodyDiagnostic");
-            public static DiagnosticDescriptor Desciptor5 = new TriggerDiagnosticDescriptor("IndexerExpressionBodyDiagnostic");
-            public static DiagnosticDescriptor Desciptor6 = new TriggerDiagnosticDescriptor("MethodExpressionBodyDiagnostic");
+            public static DiagnosticDescriptor Desciptor1 = DescriptorFactory.CreateSimpleDescriptor("CodeBlockDiagnostic");
+            public static DiagnosticDescriptor Desciptor2 = DescriptorFactory.CreateSimpleDescriptor("EqualsValueDiagnostic");
+            public static DiagnosticDescriptor Desciptor3 = DescriptorFactory.CreateSimpleDescriptor("ConstructorInitializerDiagnostic");
+            public static DiagnosticDescriptor Desciptor4 = DescriptorFactory.CreateSimpleDescriptor("PropertyExpressionBodyDiagnostic");
+            public static DiagnosticDescriptor Desciptor5 = DescriptorFactory.CreateSimpleDescriptor("IndexerExpressionBodyDiagnostic");
+            public static DiagnosticDescriptor Desciptor6 = DescriptorFactory.CreateSimpleDescriptor("MethodExpressionBodyDiagnostic");
 
             public CodeBlockOrSyntaxNodeAnalyzer(bool isCodeBlockAnalyzer)
             {
@@ -936,6 +934,6 @@ public override void Initialize(AnalysisContext context)
                     ctxt.ReportDiagnostic(CodeAnalysis.Diagnostic.Create(Desciptor1, method.Locations[0], method.ToDisplayString()));
                 }, SymbolKind.Method);
             }
-        } 
+        }
     }
 }

src/Compilers/Core/Portable/CodeAnalysis.csproj

@@ -174,7 +174,6 @@
     <Compile Include="Diagnostic\CommonDiagnosticComparer.cs" />
     <Compile Include="Diagnostic\CommonMessageProvider.cs" />
     <Compile Include="Diagnostic\Diagnostic.cs" />
-    <Compile Include="Diagnostic\TriggerDiagnosticDescriptor.cs" />
     <Compile Include="Diagnostic\WellKnownDiagnosticTags.cs" />
     <Compile Include="Diagnostic\Diagnostic_SimpleDiagnostic.cs" />
     <Compile Include="DiagnosticAnalyzer\DiagnosticAnalysisContext.cs" />

src/Compilers/Core/Portable/Diagnostic/DiagnosticDescriptor.cs

@@ -1,18 +1,17 @@
 // 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 Roslyn.Utilities;
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
-using System.Globalization;
 using Microsoft.CodeAnalysis.Diagnostics;
+using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis
 {
     /// <summary>
     /// Provides a description about a <see cref="Diagnostic"/>
     /// </summary>
-    public class DiagnosticDescriptor : IEquatable<DiagnosticDescriptor>
+    public sealed class DiagnosticDescriptor : IEquatable<DiagnosticDescriptor>
     {
         /// <summary>
         /// An unique identifier for the diagnostic.

src/Compilers/Core/Portable/PublicAPI.txt

@@ -1383,8 +1383,6 @@ Microsoft.CodeAnalysis.Text.TextSpan.Overlap(Microsoft.CodeAnalysis.Text.TextSpa
 Microsoft.CodeAnalysis.Text.TextSpan.OverlapsWith(Microsoft.CodeAnalysis.Text.TextSpan span)
 Microsoft.CodeAnalysis.Text.TextSpan.Start.get
 Microsoft.CodeAnalysis.Text.TextSpan.TextSpan(int start, int length)
-Microsoft.CodeAnalysis.TriggerDiagnosticDescriptor
-Microsoft.CodeAnalysis.TriggerDiagnosticDescriptor.TriggerDiagnosticDescriptor(string id, params string[] customTags)
 Microsoft.CodeAnalysis.TypeInfo
 Microsoft.CodeAnalysis.TypeInfo.ConvertedType.get
 Microsoft.CodeAnalysis.TypeInfo.Equals(Microsoft.CodeAnalysis.TypeInfo other)
@@ -2128,4 +2126,4 @@ virtual Microsoft.CodeAnalysis.Text.SourceText.ToString(Microsoft.CodeAnalysis.T
 virtual Microsoft.CodeAnalysis.Text.SourceText.WithChanges(System.Collections.Generic.IEnumerable<Microsoft.CodeAnalysis.Text.TextChange> changes)
 virtual Microsoft.CodeAnalysis.Text.SourceText.Write(System.IO.TextWriter writer, Microsoft.CodeAnalysis.Text.TextSpan span, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken))
 virtual Microsoft.CodeAnalysis.Text.TextLineCollection.GetLineFromPosition(int position)
-virtual Microsoft.CodeAnalysis.Text.TextLineCollection.GetLinePosition(int position)
+virtual Microsoft.CodeAnalysis.Text.TextLineCollection.GetLinePosition(int position)

src/Compilers/VisualBasic/Test/Semantic/Diagnostics/DiagnosticAnalyzerTests.vb

@@ -1,9 +1,7 @@
 ' Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 Imports System.Collections.Immutable
-Imports System.Globalization
 Imports System.Runtime.Serialization
-Imports System.Threading
 Imports Microsoft.CodeAnalysis.Diagnostics
 Imports Microsoft.CodeAnalysis.Diagnostics.VisualBasic
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
@@ -523,7 +521,7 @@ End Namespace
         Private Class CodeBlockAnalyzer
             Inherits DiagnosticAnalyzer
 
-            Private Shared Descriptor As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("CodeBlockDiagnostic")
+            Private Shared Descriptor As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("CodeBlockDiagnostic")
 
             Public Overrides ReadOnly Property SupportedDiagnostics As ImmutableArray(Of DiagnosticDescriptor)
                 Get

src/Diagnostics/Roslyn/Core/Maintainability/UnusedDeclarationsAnalyzer.cs

@@ -20,7 +20,8 @@ internal abstract partial class UnusedDeclarationsAnalyzer<TLanguageKindEnum> :
 
         internal static readonly DiagnosticDescriptor s_rule = new DiagnosticDescriptor(RoslynDiagnosticIds.DeadCodeRuleId, s_title, s_messageFormat, Category, DiagnosticSeverity.Warning, isEnabledByDefault: true);
 
-        internal static readonly DiagnosticDescriptor s_triggerRule = new TriggerDiagnosticDescriptor(RoslynDiagnosticIds.DeadCodeTriggerRuleId, WellKnownDiagnosticTags.Unnecessary, WellKnownDiagnosticTags.Telemetry);
+        internal static readonly DiagnosticDescriptor s_triggerRule = new DiagnosticDescriptor(RoslynDiagnosticIds.DeadCodeTriggerRuleId, title: "", messageFormat: "", category: "", defaultSeverity: DiagnosticSeverity.Hidden, isEnabledByDefault: true,
+                                                                                               customTags: new[] { WellKnownDiagnosticTags.NotConfigurable, WellKnownDiagnosticTags.Unnecessary, WellKnownDiagnosticTags.Telemetry });
 
         public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics
         {

src/EditorFeatures/CSharpTest/Diagnostics/DiagnosticAnalyzerDriver/DiagnosticAnalyzerDriverTests.cs

@@ -4,7 +4,6 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
-using System.Threading;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Test.Utilities;
 using Microsoft.CodeAnalysis.Diagnostics;
@@ -253,7 +252,7 @@ void F(int x = 0, int y = 1, int z = 2)
 
         private class CodeBlockAnalyzerFactory : DiagnosticAnalyzer
         {
-            public static DiagnosticDescriptor Desciptor = new TriggerDiagnosticDescriptor("DummyDiagnostic");
+            public static DiagnosticDescriptor Desciptor = DescriptorFactory.CreateSimpleDescriptor("DummyDiagnostic");
 
             public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics
             {

src/EditorFeatures/CSharpTest/Diagnostics/FixAllProvider/BatchFixerTests.cs

@@ -23,7 +23,7 @@ internal override Tuple<DiagnosticAnalyzer, CodeFixProvider> CreateDiagnosticPro
         [DiagnosticAnalyzer(LanguageNames.CSharp)]
         private class QualifyWithThisAnalyzer : DiagnosticAnalyzer
         {
-            public static readonly DiagnosticDescriptor Descriptor = new TriggerDiagnosticDescriptor("QualifyWithThis");
+            public static readonly DiagnosticDescriptor Descriptor = DescriptorFactory.CreateSimpleDescriptor("QualifyWithThis");
 
             public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics
             {

src/EditorFeatures/Core/Implementation/RenameTracking/RenameTrackingDiagnosticAnalyzer.cs

@@ -10,8 +10,9 @@ namespace Microsoft.CodeAnalysis.Editor.Implementation.RenameTracking
     internal sealed class RenameTrackingDiagnosticAnalyzer : DiagnosticAnalyzer, IBuiltInAnalyzer
     {
         public const string DiagnosticId = "RenameTracking";
-        public static DiagnosticDescriptor DiagnosticDescriptor = new TriggerDiagnosticDescriptor(
-            DiagnosticId,
+        public static DiagnosticDescriptor DiagnosticDescriptor = new DiagnosticDescriptor(
+            DiagnosticId, title: "", messageFormat: "", category: "",
+            defaultSeverity: DiagnosticSeverity.Hidden, isEnabledByDefault: true,
             customTags: DiagnosticCustomTags.Microsoft.Append(WellKnownDiagnosticTags.NotConfigurable));
 
         internal const string RenameFromPropertyKey = "RenameFrom";

src/EditorFeatures/Test2/Diagnostics/DiagnosticServiceTests.vb

@@ -8,6 +8,7 @@ Imports Microsoft.CodeAnalysis.Diagnostics
 Imports Microsoft.CodeAnalysis.Diagnostics.EngineV1
 Imports Microsoft.CodeAnalysis.Editor.UnitTests.Diagnostics
 Imports Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces
+Imports Microsoft.CodeAnalysis.Test.Utilities
 Imports Microsoft.CodeAnalysis.Text
 Imports Roslyn.Utilities
 Imports Xunit.Sdk
@@ -1124,7 +1125,7 @@ public class B
                 Me.indexOfDeclToReportDiagnostic = indexOfDeclToReportDiagnostic
             End Sub
 
-            Public Shared ReadOnly DiagDescriptor As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("DummyDiagnostic")
+            Public Shared ReadOnly DiagDescriptor As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("DummyDiagnostic")
 
             Public Overrides ReadOnly Property SupportedDiagnostics As ImmutableArray(Of DiagnosticDescriptor)
                 Get
@@ -1168,7 +1169,7 @@ public class B
         Private Class CodeBlockStartedAnalyzer(Of TLanguageKindEnum As Structure)
             Inherits DiagnosticAnalyzer
 
-            Public Shared Descriptor As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("DummyDiagnostic")
+            Public Shared Descriptor As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("DummyDiagnostic")
 
             Public Overrides ReadOnly Property SupportedDiagnostics As ImmutableArray(Of DiagnosticDescriptor)
                 Get
@@ -1196,7 +1197,7 @@ public class B
         Private Class CodeBlockEndedAnalyzer
             Inherits DiagnosticAnalyzer
 
-            Public Shared Descriptor As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("DummyDiagnostic")
+            Public Shared Descriptor As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("DummyDiagnostic")
 
             Public Overrides ReadOnly Property SupportedDiagnostics As ImmutableArray(Of DiagnosticDescriptor)
                 Get
@@ -1222,7 +1223,7 @@ public class B
         Private Class CodeBlockStartedAndEndedAnalyzer(Of TLanguageKindEnum As Structure)
             Inherits DiagnosticAnalyzer
 
-            Public Shared Descriptor As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("DummyDiagnostic")
+            Public Shared Descriptor As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("DummyDiagnostic")
 
             Public Overrides ReadOnly Property SupportedDiagnostics As ImmutableArray(Of DiagnosticDescriptor)
                 Get
@@ -1248,7 +1249,7 @@ public class B
         Private Class CompilationEndedAnalyzer
             Inherits DiagnosticAnalyzer
 
-            Public Shared Descriptor As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("CompilationEndedAnalyzerDiagnostic")
+            Public Shared Descriptor As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("CompilationEndedAnalyzerDiagnostic")
 
             Public Overrides ReadOnly Property SupportedDiagnostics As ImmutableArray(Of DiagnosticDescriptor)
                 Get
@@ -1312,12 +1313,12 @@ public class B
 
             Private ReadOnly _isCodeBlockAnalyzer As Boolean
 
-            Public Shared Desciptor1 As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("CodeBlockDiagnostic")
-            Public Shared Desciptor2 As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("EqualsValueDiagnostic")
-            Public Shared Desciptor3 As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("ConstructorInitializerDiagnostic")
-            Public Shared Desciptor4 As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("PropertyExpressionBodyDiagnostic")
-            Public Shared Desciptor5 As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("IndexerExpressionBodyDiagnostic")
-            Public Shared Desciptor6 As DiagnosticDescriptor = New TriggerDiagnosticDescriptor("MethodExpressionBodyDiagnostic")
+            Public Shared Desciptor1 As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("CodeBlockDiagnostic")
+            Public Shared Desciptor2 As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("EqualsValueDiagnostic")
+            Public Shared Desciptor3 As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("ConstructorInitializerDiagnostic")
+            Public Shared Desciptor4 As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("PropertyExpressionBodyDiagnostic")
+            Public Shared Desciptor5 As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("IndexerExpressionBodyDiagnostic")
+            Public Shared Desciptor6 As DiagnosticDescriptor = DescriptorFactory.CreateSimpleDescriptor("MethodExpressionBodyDiagnostic")
 
             Public Sub New(isCodeBlockAnalyzer As Boolean)
                 _isCodeBlockAnalyzer = isCodeBlockAnalyzer

src/Features/Core/Diagnostics/Analyzers/RemoveUnnecessaryImportsDiagnosticAnalyzerBase.cs

@@ -5,7 +5,6 @@
 using System.Collections.Immutable;
 using System.Linq;
 using System.Threading;
-using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
@@ -27,7 +26,14 @@ internal abstract class RemoveUnnecessaryImportsDiagnosticAnalyzerBase : Diagnos
                                                                                             isEnabledByDefault: true,
                                                                                             customTags: DiagnosticCustomTags.Unnecessary);
 
-        private static readonly DiagnosticDescriptor s_fixableIdDescriptor = new TriggerDiagnosticDescriptor(DiagnosticFixableId);
+        // The NotConfigurable custom tag ensures that user can't turn this diagnostic into a warning / error via
+        // ruleset editor or solution explorer. Setting messageFormat to empty string ensures that we won't display
+        // this diagnostic in the preview pane header.
+        private static readonly DiagnosticDescriptor s_fixableIdDescriptor = new DiagnosticDescriptor(DiagnosticFixableId,
+                                                                                            title: "", messageFormat: "", category: "",
+                                                                                            defaultSeverity: DiagnosticSeverity.Hidden,
+                                                                                            isEnabledByDefault: true,
+                                                                                            customTags: WellKnownDiagnosticTags.NotConfigurable);
 
         private static readonly ImmutableArray<DiagnosticDescriptor> s_descriptors = ImmutableArray.Create(s_fixableIdDescriptor, s_classificationIdDescriptor);
 

src/Test/Utilities/DescriptorFactory.cs

@@ -0,0 +1,30 @@
+// 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 Microsoft.CodeAnalysis;
+
+namespace Roslyn.Test.Utilities
+{
+    /// <summary>
+    /// Factory for creating different kinds of <see cref="DiagnosticDescriptor"/>s for use in tests.
+    /// </summary>
+    public static class DescriptorFactory
+    {
+        /// <summary>
+        /// Creates a <see cref="DiagnosticDescriptor"/> with specified <see cref="DiagnosticDescriptor.Id"/>.
+        /// </summary>
+        /// <remarks>
+        /// Returned <see cref="DiagnosticDescriptor"/> has
+        /// - empty <see cref="DiagnosticDescriptor.Title"/>, <see cref="DiagnosticDescriptor.MessageFormat"/> and <see cref="DiagnosticDescriptor.Category"/>
+        /// - <see cref="DiagnosticDescriptor.DefaultSeverity"/> set to <see cref="DiagnosticSeverity.Hidden"/>
+        /// - <see cref="WellKnownDiagnosticTags.NotConfigurable"/> custom tag added in <see cref="DiagnosticDescriptor.CustomTags"/>.
+        /// </remarks>
+        /// <param name="id">The value for <see cref="DiagnosticDescriptor.Id"/>.</param>
+        /// <returns>A <see cref="DiagnosticDescriptor"/> with specified <see cref="DiagnosticDescriptor.Id"/>.</returns>
+        public static DiagnosticDescriptor CreateSimpleDescriptor(string id)
+        {
+            return new DiagnosticDescriptor(id, title: "", messageFormat: "", category: "",
+                defaultSeverity: DiagnosticSeverity.Hidden, isEnabledByDefault: true,
+                customTags: WellKnownDiagnosticTags.NotConfigurable);
+        }
+    }
+}

src/Test/Utilities/TestUtilities.csproj

@@ -123,6 +123,7 @@
     <Compile Include="ConsoleOutput.cs" />
     <Compile Include="CultureContext.cs" />
     <Compile Include="DiagnosticDescription.cs" />
+    <Compile Include="DescriptorFactory.cs" />
     <Compile Include="DiagnosticExtensions.cs" />
     <Compile Include="DiffUtil.cs" />
     <Compile Include="DisposableDirectory.cs" />
@@ -229,4 +230,4 @@
     <Import Project="..\..\..\build\Roslyn.Toolsets.Xunit.targets" />
     <Import Project="$(SolutionDir)\.nuget\NuGet.targets" Condition="Exists('$(SolutionDir)\.nuget\NuGet.targets')" />
   </ImportGroup>
-</Project>
+</Project>