Simplify CreateWithLocationTags API

src/Analyzers/CSharp/Analyzers/InvokeDelegateWithConditionalAccess/InvokeDelegateWithConditionalAccessAnalyzer.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.CSharp.CodeStyle;
@@ -11,7 +10,6 @@
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Text;
-using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CSharp.InvokeDelegateWithConditionalAccess
 {
@@ -173,9 +171,8 @@ private void SyntaxNodeAction(SyntaxNodeAnalysisContext syntaxContext)
                 Descriptor,
                 fadeLocation,
                 ReportDiagnostic.Default,
-                additionalLocations.Add(fadeLocation),
-                tagIndices: ImmutableDictionary<string, IEnumerable<int>>.Empty
-                    .Add(nameof(WellKnownDiagnosticTags.Unnecessary), SpecializedCollections.SingletonEnumerable(additionalLocations.Length)),
+                additionalLocations,
+                additionalUnnecessaryLocations: ImmutableArray.Create(fadeLocation),
                 properties));
 
             // Put a diagnostic with the appropriate severity on the expression-statement itself.
@@ -193,9 +190,8 @@ private void SyntaxNodeAction(SyntaxNodeAnalysisContext syntaxContext)
                     Descriptor,
                     fadeLocation,
                     ReportDiagnostic.Default,
-                    additionalLocations.Add(fadeLocation),
-                    tagIndices: ImmutableDictionary<string, IEnumerable<int>>.Empty
-                        .Add(nameof(WellKnownDiagnosticTags.Unnecessary), SpecializedCollections.SingletonEnumerable(additionalLocations.Length)),
+                    additionalLocations,
+                    additionalUnnecessaryLocations: ImmutableArray.Create(fadeLocation),
                     properties));
             }
         }

src/Analyzers/CSharp/Analyzers/RemoveUnreachableCode/CSharpRemoveUnreachableCodeDiagnosticAnalyzer.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
 using Microsoft.CodeAnalysis.CodeStyle;
@@ -114,14 +113,16 @@ private void AnalyzeSemanticModel(SemanticModelAnalysisContext context)
 
             // 'additionalLocations' is how we always pass along the locaiton of the first unreachable
             // statement in this group.
-            var additionalLocations = SpecializedCollections.SingletonEnumerable(firstStatementLocation);
+            var additionalLocations = ImmutableArray.Create(firstStatementLocation);
 
             if (fadeOutCode)
             {
-                var tagIndices = ImmutableDictionary<string, IEnumerable<int>>.Empty
-                    .Add(nameof(WellKnownDiagnosticTags.Unnecessary), new int[] { 0 });
-                context.ReportDiagnostic(
-                    DiagnosticHelper.CreateWithLocationTags(Descriptor, firstStatementLocation, ReportDiagnostic.Default, additionalLocations, tagIndices));
+                context.ReportDiagnostic(DiagnosticHelper.CreateWithLocationTags(
+                    Descriptor,
+                    firstStatementLocation,
+                    ReportDiagnostic.Default,
+                    additionalLocations: ImmutableArray<Location>.Empty,
+                    additionalUnnecessaryLocations: additionalLocations));
             }
             else
             {
@@ -134,22 +135,18 @@ private void AnalyzeSemanticModel(SemanticModelAnalysisContext context)
             {
                 var span = TextSpan.FromBounds(section[0].FullSpan.Start, section.Last().FullSpan.End);
                 var location = root.SyntaxTree.GetLocation(span);
+                var additionalUnnecessaryLocations = ImmutableArray<Location>.Empty;
 
                 // Mark subsequent sections as being 'cascaded'.  We don't need to actually process them
                 // when doing a fix-all as they'll be scooped up when we process the fix for the first
                 // section.
                 if (fadeOutCode)
                 {
-                    var tagIndices = ImmutableDictionary<string, IEnumerable<int>>.Empty
-                        .Add(nameof(WellKnownDiagnosticTags.Unnecessary), new int[] { additionalLocations.Count() });
-                    context.ReportDiagnostic(
-                        DiagnosticHelper.CreateWithLocationTags(Descriptor, location, ReportDiagnostic.Default, additionalLocations.Concat(location), tagIndices, s_subsequentSectionProperties));
-                }
-                else
-                {
-                    context.ReportDiagnostic(
-                        Diagnostic.Create(Descriptor, location, additionalLocations, s_subsequentSectionProperties));
+                    additionalUnnecessaryLocations = ImmutableArray.Create(location);
                 }
+
+                context.ReportDiagnostic(
+                    DiagnosticHelper.CreateWithLocationTags(Descriptor, location, ReportDiagnostic.Default, additionalLocations, additionalUnnecessaryLocations, s_subsequentSectionProperties));
             }
         }
     }

src/Analyzers/CSharp/Analyzers/UseDefaultLiteral/CSharpUseDefaultLiteralDiagnosticAnalyzer.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.CSharp.CodeStyle;
@@ -52,9 +51,8 @@ private void AnalyzeSyntax(SyntaxNodeAnalysisContext context)
                     Descriptor,
                     defaultExpression.GetLocation(),
                     preference.Notification.Severity,
-                    additionalLocations: new[] { defaultExpression.SyntaxTree.GetLocation(fadeSpan) },
-                    tagIndices: ImmutableDictionary<string, IEnumerable<int>>.Empty
-                        .Add(nameof(WellKnownDiagnosticTags.Unnecessary), new int[] { 0 })));
+                    additionalLocations: ImmutableArray<Location>.Empty,
+                    additionalUnnecessaryLocations: ImmutableArray.Create(defaultExpression.SyntaxTree.GetLocation(fadeSpan))));
         }
     }
 }

src/Analyzers/CSharp/Analyzers/UseInferredMemberName/CSharpUseInferredMemberNameDiagnosticAnalyzer.cs

@@ -4,7 +4,6 @@
 
 #nullable enable
 
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Threading;
 using Microsoft.CodeAnalysis.CodeStyle;
@@ -61,9 +60,8 @@ private void ReportDiagnosticsIfNeeded(NameColonSyntax nameColon, SyntaxNodeAnal
                     Descriptor,
                     nameColon.GetLocation(),
                     preference.Notification.Severity,
-                    additionalLocations: new[] { syntaxTree.GetLocation(fadeSpan) },
-                    tagIndices: ImmutableDictionary<string, IEnumerable<int>>.Empty
-                        .Add(nameof(WellKnownDiagnosticTags.Unnecessary), new int[] { 0 })));
+                    additionalLocations: ImmutableArray<Location>.Empty,
+                    additionalUnnecessaryLocations: ImmutableArray.Create(syntaxTree.GetLocation(fadeSpan))));
         }
 
         private void ReportDiagnosticsIfNeeded(NameEqualsSyntax nameEquals, SyntaxNodeAnalysisContext context, AnalyzerOptions options, SyntaxTree syntaxTree, CancellationToken cancellationToken)
@@ -89,9 +87,8 @@ private void ReportDiagnosticsIfNeeded(NameEqualsSyntax nameEquals, SyntaxNodeAn
                     Descriptor,
                     nameEquals.GetLocation(),
                     preference.Notification.Severity,
-                    additionalLocations: new[] { syntaxTree.GetLocation(fadeSpan) },
-                    tagIndices: ImmutableDictionary<string, IEnumerable<int>>.Empty
-                        .Add(nameof(WellKnownDiagnosticTags.Unnecessary), new int[] { 0 })));
+                    additionalLocations: ImmutableArray<Location>.Empty,
+                    additionalUnnecessaryLocations: ImmutableArray.Create(syntaxTree.GetLocation(fadeSpan))));
         }
     }
 }

src/Analyzers/Core/Analyzers/AbstractBuiltInCodeStyleDiagnosticAnalyzer.cs

@@ -33,7 +33,7 @@ internal abstract class AbstractBuiltInCodeStyleDiagnosticAnalyzer : AbstractCod
         /// Message for the diagnostic descriptor.
         /// <see langword="null"/> if the message is identical to the title.
         /// </param>
-        /// <param name="isUnnecessary"></param>
+        /// <param name="isUnnecessary"><see langword="true"/> if the diagnostic is reported on unnecessary code; otherwise, <see langword="false"/>.</param>
         /// <param name="configurable">Flag indicating if the reported diagnostics are configurable by the end users</param>
         protected AbstractBuiltInCodeStyleDiagnosticAnalyzer(
             string diagnosticId,
@@ -62,7 +62,7 @@ internal abstract class AbstractBuiltInCodeStyleDiagnosticAnalyzer : AbstractCod
         /// Message for the diagnostic descriptor.
         /// <see langword="null"/> if the message is identical to the title.
         /// </param>
-        /// <param name="isUnnecessary"></param>
+        /// <param name="isUnnecessary"><see langword="true"/> if the diagnostic is reported on unnecessary code; otherwise, <see langword="false"/>.</param>
         /// <param name="configurable">Flag indicating if the reported diagnostics are configurable by the end users</param>
         protected AbstractBuiltInCodeStyleDiagnosticAnalyzer(
             string diagnosticId,
@@ -90,7 +90,7 @@ internal abstract class AbstractBuiltInCodeStyleDiagnosticAnalyzer : AbstractCod
         /// Message for the diagnostic descriptor.
         /// Null if the message is identical to the title.
         /// </param>
-        /// <param name="isUnnecessary"></param>
+        /// <param name="isUnnecessary"><see langword="true"/> if the diagnostic is reported on unnecessary code; otherwise, <see langword="false"/>.</param>
         /// <param name="configurable">Flag indicating if the reported diagnostics are configurable by the end users</param>
         protected AbstractBuiltInCodeStyleDiagnosticAnalyzer(
             string diagnosticId,
@@ -120,7 +120,7 @@ internal abstract class AbstractBuiltInCodeStyleDiagnosticAnalyzer : AbstractCod
         /// Message for the diagnostic descriptor.
         /// Null if the message is identical to the title.
         /// </param>
-        /// <param name="isUnnecessary"></param>
+        /// <param name="isUnnecessary"><see langword="true"/> if the diagnostic is reported on unnecessary code; otherwise, <see langword="false"/>.</param>
         /// <param name="configurable">Flag indicating if the reported diagnostics are configurable by the end users</param>
         protected AbstractBuiltInCodeStyleDiagnosticAnalyzer(
             string diagnosticId,

src/Analyzers/Core/Analyzers/Helpers/DiagnosticHelper.cs

@@ -69,11 +69,13 @@ internal static class DiagnosticHelper
         /// <param name="additionalLocations">
         /// An optional set of additional locations related to the diagnostic.
         /// Typically, these are locations of other items referenced in the message.
-        /// If null, <see cref="Diagnostic.AdditionalLocations"/> will return an empty list.
+        /// These locations are joined with <paramref name="additionalUnnecessaryLocations"/> to produce the value for
+        /// <see cref="Diagnostic.AdditionalLocations"/>.
         /// </param>
-        /// <param name="tagIndices">
-        /// a map of location tag to index in additional locations.
-        /// "AbstractRemoveUnnecessaryParenthesesDiagnosticAnalyzer" for an example of usage.
+        /// <param name="additionalUnnecessaryLocations">
+        /// An optional set of additional locations indicating unnecessary code related to the diagnostic.
+        /// These locations are joined with <paramref name="additionalLocations"/> to produce the value for
+        /// <see cref="Diagnostic.AdditionalLocations"/>.
         /// </param>
         /// <param name="messageArgs">Arguments to the message of the diagnostic.</param>
         /// <returns>The <see cref="Diagnostic"/> instance.</returns>
@@ -81,11 +83,74 @@ internal static class DiagnosticHelper
             DiagnosticDescriptor descriptor,
             Location location,
             ReportDiagnostic effectiveSeverity,
-            IEnumerable<Location> additionalLocations,
-            IDictionary<string, IEnumerable<int>> tagIndices,
+            ImmutableArray<Location> additionalLocations,
+            ImmutableArray<Location> additionalUnnecessaryLocations,
             params object[] messageArgs)
         {
-            return CreateWithLocationTags(descriptor, location, effectiveSeverity, additionalLocations, tagIndices, ImmutableDictionary<string, string>.Empty, messageArgs);
+            if (additionalUnnecessaryLocations.IsEmpty)
+            {
+                return Create(descriptor, location, effectiveSeverity, additionalLocations, ImmutableDictionary<string, string>.Empty, messageArgs);
+            }
+
+            var tagIndices = ImmutableDictionary<string, IEnumerable<int>>.Empty
+                .Add(WellKnownDiagnosticTags.Unnecessary, Enumerable.Range(additionalLocations.Length, additionalUnnecessaryLocations.Length));
+            return CreateWithLocationTags(
+                descriptor,
+                location,
+                effectiveSeverity,
+                additionalLocations.AddRange(additionalUnnecessaryLocations),
+                tagIndices,
+                ImmutableDictionary<string, string>.Empty,
+                messageArgs);
+        }
+
+        /// <summary>
+        /// Create a diagnostic that adds properties specifying a tag for a set of locations.
+        /// </summary>
+        /// <param name="descriptor">A <see cref="DiagnosticDescriptor"/> describing the diagnostic.</param>
+        /// <param name="location">An optional primary location of the diagnostic. If null, <see cref="Location"/> will return <see cref="Location.None"/>.</param>
+        /// <param name="effectiveSeverity">Effective severity of the diagnostic.</param>
+        /// <param name="additionalLocations">
+        /// An optional set of additional locations related to the diagnostic.
+        /// Typically, these are locations of other items referenced in the message.
+        /// These locations are joined with <paramref name="additionalUnnecessaryLocations"/> to produce the value for
+        /// <see cref="Diagnostic.AdditionalLocations"/>.
+        /// </param>
+        /// <param name="additionalUnnecessaryLocations">
+        /// An optional set of additional locations indicating unnecessary code related to the diagnostic.
+        /// These locations are joined with <paramref name="additionalLocations"/> to produce the value for
+        /// <see cref="Diagnostic.AdditionalLocations"/>.
+        /// </param>
+        /// <param name="properties">
+        /// An optional set of name-value pairs by means of which the analyzer that creates the diagnostic
+        /// can convey more detailed information to the fixer.
+        /// </param>
+        /// <param name="messageArgs">Arguments to the message of the diagnostic.</param>
+        /// <returns>The <see cref="Diagnostic"/> instance.</returns>
+        public static Diagnostic CreateWithLocationTags(
+            DiagnosticDescriptor descriptor,
+            Location location,
+            ReportDiagnostic effectiveSeverity,
+            ImmutableArray<Location> additionalLocations,
+            ImmutableArray<Location> additionalUnnecessaryLocations,
+            ImmutableDictionary<string, string> properties,
+            params object[] messageArgs)
+        {
+            if (additionalUnnecessaryLocations.IsEmpty)
+            {
+                return Create(descriptor, location, effectiveSeverity, additionalLocations, ImmutableDictionary<string, string>.Empty, messageArgs);
+            }
+
+            var tagIndices = ImmutableDictionary<string, IEnumerable<int>>.Empty
+                .Add(WellKnownDiagnosticTags.Unnecessary, Enumerable.Range(additionalLocations.Length, additionalUnnecessaryLocations.Length));
+            return CreateWithLocationTags(
+                descriptor,
+                location,
+                effectiveSeverity,
+                additionalLocations.AddRange(additionalUnnecessaryLocations),
+                tagIndices,
+                properties,
+                messageArgs);
         }
 
         /// <summary>
@@ -97,7 +162,6 @@ internal static class DiagnosticHelper
         /// <param name="additionalLocations">
         /// An optional set of additional locations related to the diagnostic.
         /// Typically, these are locations of other items referenced in the message.
-        /// If null, <see cref="Diagnostic.AdditionalLocations"/> will return an empty list.
         /// </param>
         /// <param name="tagIndices">
         /// a map of location tag to index in additional locations.
@@ -109,7 +173,7 @@ internal static class DiagnosticHelper
         /// </param>
         /// <param name="messageArgs">Arguments to the message of the diagnostic.</param>
         /// <returns>The <see cref="Diagnostic"/> instance.</returns>
-        public static Diagnostic CreateWithLocationTags(
+        private static Diagnostic CreateWithLocationTags(
             DiagnosticDescriptor descriptor,
             Location location,
             ReportDiagnostic effectiveSeverity,

src/Analyzers/Core/Analyzers/RemoveUnnecessaryParentheses/AbstractRemoveUnnecessaryParenthesesDiagnosticAnalyzer.cs

@@ -5,7 +5,6 @@
 #nullable enable
 
 using System;
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Threading;
@@ -34,12 +33,6 @@ internal abstract class AbstractRemoveUnnecessaryParenthesesDiagnosticAnalyzer<
                 new LocalizableResourceString(nameof(AnalyzersResources.Parentheses_can_be_removed), AnalyzersResources.ResourceManager, typeof(AnalyzersResources)),
                 isUnnecessary: true);
 
-        /// <summary>
-        /// This analyzer inserts the fade locations into indices 1 and 2 inside additional locations.
-        /// </summary>
-        private static readonly ImmutableDictionary<string, IEnumerable<int>> s_fadeLocations = ImmutableDictionary<string, IEnumerable<int>>.Empty
-            .Add(nameof(WellKnownDiagnosticTags.Unnecessary), new int[] { 1, 2 });
-
         protected AbstractRemoveUnnecessaryParenthesesDiagnosticAnalyzer()
             : base(ImmutableArray.Create(s_diagnosticDescriptor))
         {
@@ -120,7 +113,8 @@ private void AnalyzeSyntax(SyntaxNodeAnalysisContext context)
             var severity = preference.Notification.Severity;
 
             var additionalLocations = ImmutableArray.Create(
-                parenthesizedExpression.GetLocation(),
+                parenthesizedExpression.GetLocation());
+            var additionalUnnecessaryLocations = ImmutableArray.Create(
                 parenthesizedExpression.GetFirstToken().GetLocation(),
                 parenthesizedExpression.GetLastToken().GetLocation());
 
@@ -129,7 +123,7 @@ private void AnalyzeSyntax(SyntaxNodeAnalysisContext context)
                 GetDiagnosticSquiggleLocation(parenthesizedExpression, context.CancellationToken),
                 severity,
                 additionalLocations,
-                s_fadeLocations));
+                additionalUnnecessaryLocations));
         }
 
         /// <summary>

src/Analyzers/Core/Analyzers/SimplifyInterpolation/AbstractSimplifyInterpolationDiagnosticAnalyzer.cs

@@ -2,9 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System.Collections.Generic;
 using System.Collections.Immutable;
-using System.Linq;
 using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.EmbeddedLanguages.VirtualChars;
@@ -67,13 +65,17 @@ private void AnalyzeInterpolation(OperationAnalysisContext context)
                 return;
             }
 
+            // The diagnostic itself fades the first unnecessary location, and the remaining locations are passed as
+            // additional unnecessary locations.
+            var firstUnnecessaryLocation = unnecessaryLocations[0];
+            var remainingUnnecessaryLocations = unnecessaryLocations.RemoveAt(0);
+
             context.ReportDiagnostic(DiagnosticHelper.CreateWithLocationTags(
                 Descriptor,
-                unnecessaryLocations.First(),
+                firstUnnecessaryLocation,
                 option.Notification.Severity,
-                additionalLocations: ImmutableArray.Create(interpolation.Syntax.GetLocation()).AddRange(unnecessaryLocations.Skip(1)),
-                tagIndices: ImmutableDictionary<string, IEnumerable<int>>.Empty
-                    .Add(nameof(WellKnownDiagnosticTags.Unnecessary), Enumerable.Range(1, unnecessaryLocations.Length - 1))));
+                additionalLocations: ImmutableArray.Create(interpolation.Syntax.GetLocation()),
+                additionalUnnecessaryLocations: remainingUnnecessaryLocations));
         }
     }
 }

src/Analyzers/Core/Analyzers/UseCollectionInitializer/AbstractUseCollectionInitializerDiagnosticAnalyzer.cs

@@ -5,13 +5,11 @@
 #nullable enable
 
 using System.Collections;
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.LanguageServices;
 using Microsoft.CodeAnalysis.Text;
-using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.UseCollectionInitializer
 {
@@ -146,18 +144,20 @@ private void AnalyzeNode(SyntaxNodeAnalysisContext context, INamedTypeSymbol ien
                 if (syntaxFacts.IsInvocationExpression(expression))
                 {
                     var arguments = syntaxFacts.GetArgumentsOfInvocationExpression(expression);
-                    var location1 = Location.Create(syntaxTree, TextSpan.FromBounds(
-                        match.SpanStart, arguments[0].SpanStart));
+                    var additionalUnnecessaryLocations = ImmutableArray.Create(
+                        syntaxTree.GetLocation(TextSpan.FromBounds(match.SpanStart, arguments[0].SpanStart)),
+                        syntaxTree.GetLocation(TextSpan.FromBounds(arguments.Last().FullSpan.End, match.Span.End)));
+
+                    // Report the diagnostic at the first unnecessary location. This is the location where the code fix
+                    // will be offered.
+                    var location1 = additionalUnnecessaryLocations[0];
 
                     context.ReportDiagnostic(DiagnosticHelper.CreateWithLocationTags(
                         Descriptor,
                         location1,
                         ReportDiagnostic.Default,
-                        additionalLocations: locations
-                            .Add(location1)
-                            .Add(syntaxTree.GetLocation(TextSpan.FromBounds(arguments.Last().FullSpan.End, match.Span.End))),
-                        tagIndices: ImmutableDictionary<string, IEnumerable<int>>.Empty
-                            .Add(nameof(WellKnownDiagnosticTags.Unnecessary), new int[] { locations.Length - 1, locations.Length })));
+                        additionalLocations: locations,
+                        additionalUnnecessaryLocations: additionalUnnecessaryLocations));
                 }
             }
         }

src/Analyzers/Core/Analyzers/UseObjectInitializer/AbstractUseObjectInitializerDiagnosticAnalyzer.cs

@@ -4,14 +4,12 @@
 
 #nullable enable
 
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
 using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.LanguageServices;
 using Microsoft.CodeAnalysis.Text;
-using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.UseObjectInitializer
 {
@@ -132,11 +130,9 @@ private void AnalyzeNode(SyntaxNodeAnalysisContext context)
                         Descriptor,
                         location1,
                         ReportDiagnostic.Default,
-                        additionalLocations: locations.Add(Location.Create(syntaxTree, TextSpan.FromBounds(
-                            match.Initializer.FullSpan.End,
-                            match.Statement.Span.End))),
-                        tagIndices: ImmutableDictionary<string, IEnumerable<int>>.Empty
-                            .Add(nameof(WellKnownDiagnosticTags.Unnecessary), new int[] { locations.Length })));
+                        additionalLocations: locations,
+                        additionalUnnecessaryLocations: ImmutableArray.Create(
+                            syntaxTree.GetLocation(TextSpan.FromBounds(match.Initializer.FullSpan.End, match.Statement.Span.End)))));
                 }
                 else
                 {

src/Analyzers/VisualBasic/Analyzers/UseInferredMemberName/VisualBasicUseInferredMemberNameDiagnosticAnalyzer.vb

@@ -65,8 +65,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.UseInferredMemberName
                     Descriptor,
                     nameColonEquals.GetLocation(),
                     preference.Notification.Severity,
-                    additionalLocations:={syntaxTree.GetLocation(fadeSpan)},
-                    tagIndices:=ImmutableDictionary(Of String, IEnumerable(Of Integer)).Empty.Add(NameOf(WellKnownDiagnosticTags.Unnecessary), {0})))
+                    additionalLocations:=ImmutableArray(Of Location).Empty,
+                    additionalUnnecessaryLocations:=ImmutableArray.Create(syntaxTree.GetLocation(fadeSpan))))
         End Sub
 
         Private Sub ReportDiagnosticsIfNeeded(
@@ -95,8 +95,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.UseInferredMemberName
                     Descriptor,
                     syntaxTree.GetLocation(fadeSpan),
                     preference.Notification.Severity,
-                    additionalLocations:={syntaxTree.GetLocation(fadeSpan)},
-                    tagIndices:=ImmutableDictionary(Of String, IEnumerable(Of Integer)).Empty.Add(NameOf(WellKnownDiagnosticTags.Unnecessary), {0})))
+                    additionalLocations:=ImmutableArray(Of Location).Empty,
+                    additionalUnnecessaryLocations:=ImmutableArray.Create(syntaxTree.GetLocation(fadeSpan))))
         End Sub
     End Class
 End Namespace

src/EditorFeatures/Test/Diagnostics/DiagnosticsClassificationTaggerProviderTests.cs

@@ -59,12 +59,6 @@ public async Task Test_FadingSpans()
 
         private class Analyzer : DiagnosticAnalyzer
         {
-            // Mark elements 1, and 2 in the locations as the fading locations.
-            private static readonly ImmutableDictionary<string, IEnumerable<int>> s_fadeLocations = new Dictionary<string, IEnumerable<int>>
-            {
-                { nameof(WellKnownDiagnosticTags.Unnecessary), new int[] { 1, 2 } },
-            }.ToImmutableDictionary();
-
             private readonly DiagnosticDescriptor _rule = new DiagnosticDescriptor(
                 "test", "test", "test", "test", DiagnosticSeverity.Error, true,
                 customTags: DiagnosticCustomTags.Create(isUnnecessary: true, isConfigurable: false));
@@ -76,15 +70,16 @@ public override void Initialize(AnalysisContext context)
             {
                 context.RegisterSyntaxTreeAction(c =>
                 {
+                    var additionalLocations = ImmutableArray.Create(Location.Create(c.Tree, new TextSpan(0, 10)));
+                    var additionalUnnecessaryLocations = ImmutableArray.Create(
+                        Location.Create(c.Tree, new TextSpan(0, 1)),
+                        Location.Create(c.Tree, new TextSpan(9, 1)));
+
                     c.ReportDiagnostic(DiagnosticHelper.CreateWithLocationTags(
                         _rule, Location.Create(c.Tree, new TextSpan(0, 10)),
                         ReportDiagnostic.Error,
-                        new Location[] {
-                            Location.Create(c.Tree, new TextSpan(0, 10)),
-                            Location.Create(c.Tree, new TextSpan(0, 1)),
-                            Location.Create(c.Tree, new TextSpan(9, 1)),
-                        },
-                        s_fadeLocations));
+                        additionalLocations,
+                        additionalUnnecessaryLocations));
                 });
             }
         }