add property bag to diagnostic and remember origin of the diagnostic

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

@@ -6,6 +6,7 @@
 using System.Globalization;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
+using System.Collections.Immutable;
 
 namespace Microsoft.CodeAnalysis
 {
@@ -34,7 +35,24 @@ public static Diagnostic Create(
             Location location,
             params object[] messageArgs)
         {
-            return Create(descriptor, location, null, messageArgs);
+            return Create(descriptor, location, null, null, messageArgs);
+        }
+
+        /// <summary>
+        /// Creates a <see cref="Diagnostic"/> instance.
+        /// </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="properties">An optional set of properties of the diagnostic. If null, <see cref="Properties"/> will return <see cref="ImmutableDictionary{TKey, TValue}.Empty"/>.</param>
+        /// <param name="messageArgs">Arguments to the message of the diagnostic.</param>
+        /// <returns>The <see cref="Diagnostic"/> instance.</returns>
+        public static Diagnostic Create(
+            DiagnosticDescriptor descriptor,
+            Location location,
+            ImmutableDictionary<string, string> properties,
+            params object[] messageArgs)
+        {
+            return Create(descriptor, location, null, properties, messageArgs);
         }
 
         /// <summary>
@@ -54,6 +72,29 @@ public static Diagnostic Create(
             Location location,
             IEnumerable<Location> additionalLocations,
             params object[] messageArgs)
+        {
+            return Create(descriptor, location, additionalLocations, properties: null, messageArgs: messageArgs);
+        }
+
+        /// <summary>
+        /// Creates a <see cref="Diagnostic"/> instance.
+        /// </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="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="AdditionalLocations"/> will return an empty list.
+        /// </param>
+        /// <param name="properties">An optional set of properties of the diagnostic. If null, <see cref="Properties"/> will return <see cref="ImmutableDictionary{TKey, TValue}.Empty"/>.</param>
+        /// <param name="messageArgs">Arguments to the message of the diagnostic.</param>
+        /// <returns>The <see cref="Diagnostic"/> instance.</returns>
+        public static Diagnostic Create(
+            DiagnosticDescriptor descriptor,
+            Location location,
+            IEnumerable<Location> additionalLocations,
+            ImmutableDictionary<string, string> properties,
+            params object[] messageArgs)
         {
             if (descriptor == null)
             {
@@ -67,7 +108,8 @@ public static Diagnostic Create(
                 warningLevel: warningLevel,
                 location: location ?? Location.None,
                 additionalLocations: additionalLocations,
-                messageArgs: messageArgs);
+                messageArgs: messageArgs,
+                properties: properties);
         }
 
         /// <summary>
@@ -93,6 +135,7 @@ public static Diagnostic Create(
         /// An optional set of custom tags for the diagnostic. See <see cref="WellKnownDiagnosticTags"/> for some well known tags.
         /// If null, <see cref="CustomTags"/> will return an empty list.
         /// </param>
+        /// <param name="properties">An optional set of properties of the diagnostic. If null, <see cref="Properties"/> will return <see cref="ImmutableDictionary{TKey, TValue}.Empty"/>.</param>
         /// <returns>The <see cref="Diagnostic"/> instance.</returns>
         public static Diagnostic Create(
             string id,
@@ -107,7 +150,8 @@ public static Diagnostic Create(
             string helpLink = null,
             Location location = null,
             IEnumerable<Location> additionalLocations = null,
-            IEnumerable<string> customTags = null)
+            IEnumerable<string> customTags = null,
+            ImmutableDictionary<string, string> properties = null)
         {
             if (id == null)
             {
@@ -125,7 +169,7 @@ public static Diagnostic Create(
             }
 
             return SimpleDiagnostic.Create(id, title ?? string.Empty, category, message, description ?? string.Empty, helpLink ?? string.Empty,
-                severity, defaultSeverity, isEnabledByDefault, warningLevel, location ?? Location.None, additionalLocations, customTags);
+                severity, defaultSeverity, isEnabledByDefault, warningLevel, location ?? Location.None, additionalLocations, customTags, properties);
         }
 
         internal static Diagnostic Create(CommonMessageProvider messageProvider, int errorCode)
@@ -223,6 +267,12 @@ public bool IsWarningAsError
         /// </summary>
         internal virtual IReadOnlyList<string> CustomTags { get { return (IReadOnlyList<string>)this.Descriptor.CustomTags; } }
 
+        /// <summary>
+        /// Gets property bag for the diagnostic. it will return <see cref="ImmutableDictionary{TKey, TValue}.Empty"/> if there is no entry.
+        /// This can be used to put diagnostic specific information you want to pass around. for example, to corresponding fixer.
+        /// </summary>
+        public virtual ImmutableDictionary<string, string> Properties { get { return ImmutableDictionary<string, string>.Empty; } }
+
         string IFormattable.ToString(string ignored, IFormatProvider formatProvider)
         {
             return DiagnosticFormatter.Instance.Format(this, formatProvider);

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

@@ -22,14 +22,16 @@ internal sealed class SimpleDiagnostic : Diagnostic
             private readonly Location _location;
             private readonly IReadOnlyList<Location> _additionalLocations;
             private readonly object[] _messageArgs;
+            private readonly ImmutableDictionary<string, string> _properties;
 
             private SimpleDiagnostic(
                 DiagnosticDescriptor descriptor,
                 DiagnosticSeverity severity,
                 int warningLevel,
                 Location location,
                 IEnumerable<Location> additionalLocations,
-                object[] messageArgs)
+                object[] messageArgs,
+                ImmutableDictionary<string, string> properties)
             {
                 if ((warningLevel == 0 && severity != DiagnosticSeverity.Error) ||
                     (warningLevel != 0 && severity == DiagnosticSeverity.Error))
@@ -48,6 +50,7 @@ private SimpleDiagnostic(
                 _location = location ?? Location.None;
                 _additionalLocations = additionalLocations == null ? SpecializedCollections.EmptyReadOnlyList<Location>() : additionalLocations.ToImmutableArray();
                 _messageArgs = messageArgs ?? SpecializedCollections.EmptyArray<object>();
+                _properties = properties ?? ImmutableDictionary<string, string>.Empty;
             }
 
             internal static SimpleDiagnostic Create(
@@ -56,19 +59,21 @@ internal static SimpleDiagnostic Create(
                 int warningLevel,
                 Location location,
                 IEnumerable<Location> additionalLocations,
-                object[] messageArgs)
+                object[] messageArgs,
+                ImmutableDictionary<string, string> properties)
             {
-                return new SimpleDiagnostic(descriptor, severity, warningLevel, location, additionalLocations, messageArgs);
+                return new SimpleDiagnostic(descriptor, severity, warningLevel, location, additionalLocations, messageArgs, properties);
             }
 
             internal static SimpleDiagnostic Create(string id, LocalizableString title, string category, LocalizableString message, LocalizableString description, string helpLink,
                                       DiagnosticSeverity severity, DiagnosticSeverity defaultSeverity,
                                       bool isEnabledByDefault, int warningLevel, Location location,
-                                      IEnumerable<Location> additionalLocations, IEnumerable<string> customTags)
+                                      IEnumerable<Location> additionalLocations, IEnumerable<string> customTags,
+                                      ImmutableDictionary<string, string> properties)
             {
                 var descriptor = new DiagnosticDescriptor(id, title, message,
                      category, defaultSeverity, isEnabledByDefault, description, helpLink, customTags.ToImmutableArrayOrEmpty());
-                return new SimpleDiagnostic(descriptor, severity, warningLevel, location, additionalLocations, messageArgs: null);
+                return new SimpleDiagnostic(descriptor, severity, warningLevel, location, additionalLocations, messageArgs: null, properties: properties);
             }
 
             public override DiagnosticDescriptor Descriptor
@@ -117,6 +122,11 @@ public override IReadOnlyList<Location> AdditionalLocations
                 get { return _additionalLocations; }
             }
 
+            public override ImmutableDictionary<string, string> Properties
+            {
+                get { return _properties; }
+            }
+
             public override bool Equals(Diagnostic obj)
             {
                 var other = obj as SimpleDiagnostic;
@@ -150,7 +160,7 @@ internal override Diagnostic WithLocation(Location location)
 
                 if (location != _location)
                 {
-                    return new SimpleDiagnostic(_descriptor, _severity, _warningLevel, location, _additionalLocations, _messageArgs);
+                    return new SimpleDiagnostic(_descriptor, _severity, _warningLevel, location, _additionalLocations, _messageArgs, _properties);
                 }
 
                 return this;
@@ -161,7 +171,7 @@ internal override Diagnostic WithSeverity(DiagnosticSeverity severity)
                 if (this.Severity != severity)
                 {
                     var warningLevel = GetDefaultWarningLevel(severity);
-                    return new SimpleDiagnostic(_descriptor, severity, warningLevel, _location, _additionalLocations, _messageArgs);
+                    return new SimpleDiagnostic(_descriptor, severity, warningLevel, _location, _additionalLocations, _messageArgs, _properties);
                 }
 
                 return this;

src/Compilers/Core/Portable/DiagnosticAnalyzer/CompilerDiagnosticAnalyzer.CompilationAnalyzer.cs

@@ -1,12 +1,20 @@
 // 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.Generic;
 using System.Collections.Immutable;
 
 namespace Microsoft.CodeAnalysis.Diagnostics
 {
     internal abstract partial class CompilerDiagnosticAnalyzer : DiagnosticAnalyzer
     {
+        private const string Origin = "Origin";
+        private const string Syntactic = "Syntactic";
+        private const string Declaration = "Declaration";
+
+        private static readonly ImmutableDictionary<string, string> s_syntactic = ImmutableDictionary<string, string>.Empty.Add(Origin, Syntactic);
+        private static readonly ImmutableDictionary<string, string> s_declaration = ImmutableDictionary<string, string>.Empty.Add(Origin, Declaration);
+
         /// <summary>
         /// Per-compilation DiagnosticAnalyzer for compiler's syntax/semantic/compilation diagnostics.
         /// </summary>
@@ -23,13 +31,13 @@ public void AnalyzeSyntaxTree(SyntaxTreeAnalysisContext context)
             {
                 var semanticModel = _compilation.GetSemanticModel(context.Tree);
                 var diagnostics = semanticModel.GetSyntaxDiagnostics(cancellationToken: context.CancellationToken);
-                ReportDiagnostics(diagnostics, context.ReportDiagnostic, IsSourceLocation);
+                ReportDiagnostics(diagnostics, context.ReportDiagnostic, IsSourceLocation, s_syntactic);
             }
 
             public void AnalyzeSemanticModel(SemanticModelAnalysisContext context)
             {
                 var declDiagnostics = context.SemanticModel.GetDeclarationDiagnostics(cancellationToken: context.CancellationToken);
-                ReportDiagnostics(declDiagnostics, context.ReportDiagnostic, IsSourceLocation);
+                ReportDiagnostics(declDiagnostics, context.ReportDiagnostic, IsSourceLocation, s_declaration);
 
                 var bodyDiagnostics = context.SemanticModel.GetMethodBodyDiagnostics(cancellationToken: context.CancellationToken);
                 ReportDiagnostics(bodyDiagnostics, context.ReportDiagnostic, IsSourceLocation);
@@ -38,25 +46,83 @@ public void AnalyzeSemanticModel(SemanticModelAnalysisContext context)
             public static void AnalyzeCompilation(CompilationEndAnalysisContext context)
             {
                 var diagnostics = context.Compilation.GetDeclarationDiagnostics(cancellationToken: context.CancellationToken);
-                ReportDiagnostics(diagnostics, context.ReportDiagnostic, location => !IsSourceLocation(location));
+                ReportDiagnostics(diagnostics, context.ReportDiagnostic, location => !IsSourceLocation(location), s_declaration);
             }
 
             private static bool IsSourceLocation(Location location)
             {
                 return location != null && location.Kind == LocationKind.SourceFile;
             }
 
-            private static void ReportDiagnostics(ImmutableArray<Diagnostic> diagnostics, Action<Diagnostic> reportDiagnostic, Func<Location, bool> locationFilter)
+            private static void ReportDiagnostics(
+                ImmutableArray<Diagnostic> diagnostics,
+                Action<Diagnostic> reportDiagnostic,
+                Func<Location, bool> locationFilter,
+                ImmutableDictionary<string, string> properties = null)
             {
                 foreach (var diagnostic in diagnostics)
                 {
                     if (locationFilter(diagnostic.Location) &&
                         diagnostic.Severity != DiagnosticSeverity.Hidden)
                     {
-                        reportDiagnostic(diagnostic);
+                        var current = properties == null ? diagnostic : new CompilerDiagnostic(diagnostic, properties);
+                        reportDiagnostic(current);
                     }
                 }
             }
+
+            private class CompilerDiagnostic : Diagnostic
+            {
+                private readonly Diagnostic _original;
+                private readonly ImmutableDictionary<string, string> _properties;
+
+                public CompilerDiagnostic(Diagnostic original, ImmutableDictionary<string, string> properties)
+                {
+                    _original = original;
+                    _properties = properties;
+                }
+
+#pragma warning disable RS0013 // we are delegating to delegatee so it is okay here
+                public override DiagnosticDescriptor Descriptor => _original.Descriptor;
+#pragma warning restore RS0013 
+
+                public override string Id => _original.Id;
+                public override DiagnosticSeverity Severity => _original.Severity;
+                public override int WarningLevel => _original.WarningLevel;
+                public override Location Location => _original.Location;
+                public override IReadOnlyList<Location> AdditionalLocations => _original.AdditionalLocations;
+                public override ImmutableDictionary<string, string> Properties => _properties;
+
+                public override string GetMessage(IFormatProvider formatProvider = null)
+                {
+                    return _original.GetMessage(formatProvider);
+                }
+
+                public override bool Equals(object obj)
+                {
+                    return _original.Equals(obj);
+                }
+
+                public override int GetHashCode()
+                {
+                    return _original.GetHashCode();
+                }
+
+                public override bool Equals(Diagnostic obj)
+                {
+                    return _original.Equals(obj);
+                }
+
+                internal override Diagnostic WithLocation(Location location)
+                {
+                    return new CompilerDiagnostic(_original.WithLocation(location), _properties);
+                }
+
+                internal override Diagnostic WithSeverity(DiagnosticSeverity severity)
+                {
+                    return new CompilerDiagnostic(_original.WithSeverity(severity), _properties);
+                }
+            }
         }
     }
 }

src/Compilers/Core/Portable/DiagnosticAnalyzer/CompilerDiagnosticAnalyzer.cs

@@ -1,9 +1,6 @@
 // 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.Generic;
 using System.Collections.Immutable;
-using System.Diagnostics;
 
 namespace Microsoft.CodeAnalysis.Diagnostics
 {