Enforce that symbol comparison should use an equality comparer

src/Microsoft.CodeAnalysis.Analyzers/Core/CodeAnalysisDiagnosticsResources.resx

@@ -339,7 +339,7 @@
     <value>Upgrade MSBuildWorkspace</value>
   </data>
   <data name="CompareSymbolsCorrectlyDescription" xml:space="preserve">
-    <value>Symbols should be compared for equality, not identity.</value>
+    <value>Symbols should be compared for equality with an EqualityComparer.</value>
   </data>
   <data name="CompareSymbolsCorrectlyMessage" xml:space="preserve">
     <value>Compare symbols correctly</value>

src/Microsoft.CodeAnalysis.Analyzers/Core/MetaAnalyzers/CompareSymbolsCorrectlyAnalyzer.cs

@@ -1,8 +1,11 @@
 // 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.Linq;
 using System.Collections.Immutable;
 using Analyzer.Utilities;
 using Analyzer.Utilities.Extensions;
+using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Operations;
 
@@ -16,6 +19,8 @@ public class CompareSymbolsCorrectlyAnalyzer : DiagnosticAnalyzer
         private static readonly LocalizableString s_localizableDescription = new LocalizableResourceString(nameof(CodeAnalysisDiagnosticsResources.CompareSymbolsCorrectlyDescription), CodeAnalysisDiagnosticsResources.ResourceManager, typeof(CodeAnalysisDiagnosticsResources));
 
         private static readonly string s_symbolTypeFullName = typeof(ISymbol).FullName;
+        private const string s_symbolEqualsName = nameof(ISymbol.Equals);
+        private const string s_symbolEqualityComparerName = "Microsoft.CodeAnalysis.Shared.Utilities.SymbolEquivalenceComparer";
 
         public static readonly DiagnosticDescriptor Rule = new DiagnosticDescriptor(
             DiagnosticIds.CompareSymbolsCorrectlyRuleId,
@@ -43,11 +48,30 @@ public override void Initialize(AnalysisContext context)
                     return;
                 }
 
-                context.RegisterOperationAction(context => HandleBinaryOperator(in context, symbolType), OperationKind.BinaryOperator);
+                // Check that the s_symbolEqualityComparerName exists and can be used, otherwise the Roslyn version
+                // being used it too low to need the change for method references
+                var symbolEqualityComparerType = context.Compilation.GetTypeByMetadataName(s_symbolEqualityComparerName);
+                var operatorsToHandle = symbolEqualityComparerType is null ?
+                    new[] { OperationKind.BinaryOperator } :
+                    new[] { OperationKind.BinaryOperator, OperationKind.MethodReference };
+
+                context.RegisterOperationAction(context => HandleOperation(in context, symbolType), operatorsToHandle);
             });
         }
 
-        private void HandleBinaryOperator(in OperationAnalysisContext context, INamedTypeSymbol symbolType)
+        private void HandleOperation(in OperationAnalysisContext context, INamedTypeSymbol symbolType)
+        {
+            if (context.Operation is IBinaryOperation)
+            {
+                HandleBinaryOperator(context, symbolType);
+            }
+            if (context.Operation is IMethodReferenceOperation)
+            {
+                HandleMethodReferenceOperation(context, symbolType);
+            }
+        }
+
+        private static void HandleBinaryOperator(in OperationAnalysisContext context, INamedTypeSymbol symbolType)
         {
             var binary = (IBinaryOperation)context.Operation;
             if (binary.OperatorKind != BinaryOperatorKind.Equals && binary.OperatorKind != BinaryOperatorKind.NotEquals)
@@ -90,19 +114,27 @@ private void HandleBinaryOperator(in OperationAnalysisContext context, INamedTyp
             context.ReportDiagnostic(binary.Syntax.GetLocation().CreateDiagnostic(Rule));
         }
 
-        private static bool IsSymbolType(IOperation operation, INamedTypeSymbol symbolType)
+        private static void HandleMethodReferenceOperation(OperationAnalysisContext context, INamedTypeSymbol symbolType)
         {
-            if (operation.Type is object)
+            var methodReference = (IMethodReferenceOperation)context.Operation;
+
+            if (methodReference.Instance != null && !IsSymbolType(methodReference.Instance, symbolType))
             {
-                if (operation.Type.Equals(symbolType))
-                {
-                    return true;
-                }
+                return;
+            }
 
-                if (operation.Type.AllInterfaces.Contains(symbolType))
-                {
-                    return true;
-                }
+            var parameters = methodReference.Method.Parameters;
+            if (methodReference.Method.Name == s_symbolEqualsName && parameters.All(p => IsSymbolType(p.Type, symbolType)))
+            {
+                context.ReportDiagnostic(methodReference.Syntax.GetLocation().CreateDiagnostic(Rule));
+            }
+        }
+
+        private static bool IsSymbolType(IOperation operation, INamedTypeSymbol symbolType)
+        {
+            if (operation.Type is object && IsSymbolType(operation.Type, symbolType))
+            {
+                return true;
             }
 
             if (operation is IConversionOperation conversion)
@@ -113,6 +145,26 @@ private static bool IsSymbolType(IOperation operation, INamedTypeSymbol symbolTy
             return false;
         }
 
+        private static bool IsSymbolType(ITypeSymbol typeSymbol, INamedTypeSymbol symbolType)
+        {
+            if (typeSymbol == null)
+            {
+                return false;
+            }
+
+            if (typeSymbol.Equals(symbolType))
+            {
+                return true;
+            }
+
+            if (typeSymbol.AllInterfaces.Contains(symbolType))
+            {
+                return true;
+            }
+
+            return false;
+        }
+
         private static bool IsSymbolClassType(IOperation operation)
         {
             if (operation.Type is object)

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.cs.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">Symboly by se měly porovnat podle rovnosti, ne podle identity.</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">Symboly by se měly porovnat podle rovnosti, ne podle identity.</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.de.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">Symbole sollten hinsichtlich Gleichheit verglichen werden, nicht hinsichtlich Identität.</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">Symbole sollten hinsichtlich Gleichheit verglichen werden, nicht hinsichtlich Identität.</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.es.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">Solo se debe realizar una comparación de igualdad de los símbolos, no de identidad.</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">Solo se debe realizar una comparación de igualdad de los símbolos, no de identidad.</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.fr.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">La comparaison des symboles doit porter sur l'égalité, pas sur l'identité.</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">La comparaison des symboles doit porter sur l'égalité, pas sur l'identité.</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.it.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">È necessario confrontare i simboli per verificarne l'uguaglianza, non l'identità.</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">È necessario confrontare i simboli per verificarne l'uguaglianza, non l'identità.</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.ja.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">シンボルは、ID ではなく等値で比較する必要があります。</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">シンボルは、ID ではなく等値で比較する必要があります。</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.ko.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">기호는 ID가 아니라 같은지 비교해야 합니다.</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">기호는 ID가 아니라 같은지 비교해야 합니다.</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.pl.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">Symbole powinny być porównywane pod kątem równości, a nie tożsamości.</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">Symbole powinny być porównywane pod kątem równości, a nie tożsamości.</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.pt-BR.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">Os símbolos devem ser comparados quanto à igualdade, não à identidade.</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">Os símbolos devem ser comparados quanto à igualdade, não à identidade.</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.ru.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">Символы необходимо сравнивать на равенство, а не на тождественность.</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">Символы необходимо сравнивать на равенство, а не на тождественность.</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.tr.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">Semboller kimlik değil eşitlik için karşılaştırılmalıdır.</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">Semboller kimlik değil eşitlik için karşılaştırılmalıdır.</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.zh-Hans.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">符号应比较相等性，而不是标识。</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">符号应比较相等性，而不是标识。</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">

src/Microsoft.CodeAnalysis.Analyzers/Core/xlf/CodeAnalysisDiagnosticsResources.zh-Hant.xlf

@@ -8,8 +8,8 @@
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyDescription">
-        <source>Symbols should be compared for equality, not identity.</source>
-        <target state="translated">應比較符號是否相等，而非比較身分識別。</target>
+        <source>Symbols should be compared for equality with an EqualityComparer.</source>
+        <target state="needs-review-translation">應比較符號是否相等，而非比較身分識別。</target>
         <note />
       </trans-unit>
       <trans-unit id="CompareSymbolsCorrectlyMessage">