Fix S3875 FP: Do not raise an issue when implementing IEqualityOperators interface

analyzers/src/SonarAnalyzer.CSharp/Rules/DotNotOverloadOperatorEqual.cs → analyzers/src/SonarAnalyzer.CSharp/Rules/DoNotOverloadOperatorEqual.cs

@@ -29,65 +29,41 @@
 namespace SonarAnalyzer.Rules.CSharp
 {
     [DiagnosticAnalyzer(LanguageNames.CSharp)]
-    public sealed class DotNotOverloadOperatorEqual : SonarDiagnosticAnalyzer
+    public sealed class DoNotOverloadOperatorEqual : SonarDiagnosticAnalyzer
     {
-        internal const string DiagnosticId = "S3875";
+        private const string DiagnosticId = "S3875";
         private const string MessageFormat = "Remove this overload of 'operator =='.";
 
         private static readonly ImmutableArray<KnownType> InterfacesRelyingOnOperatorEqualOverload =
             ImmutableArray.Create(
                 KnownType.System_IComparable,
                 KnownType.System_IComparable_T,
-                KnownType.System_IEquatable_T
-            );
+                KnownType.System_IEquatable_T,
+                KnownType.System_Numerics_IEqualityOperators_TSelf_TOther_TResult);
 
-        private static readonly DiagnosticDescriptor rule =
+        private static readonly DiagnosticDescriptor Rule =
             DescriptorFactory.Create(DiagnosticId, MessageFormat);
 
-        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } = ImmutableArray.Create(rule);
+        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } = ImmutableArray.Create(Rule);
 
-        protected override void Initialize(SonarAnalysisContext context)
-        {
+        protected override void Initialize(SonarAnalysisContext context) =>
             context.RegisterSyntaxNodeActionInNonGenerated(CheckForIssue, SyntaxKind.OperatorDeclaration);
-        }
 
-        private void CheckForIssue(SyntaxNodeAnalysisContext analysisContext)
+        private static void CheckForIssue(SyntaxNodeAnalysisContext analysisContext)
         {
             var declaration = (OperatorDeclarationSyntax)analysisContext.Node;
 
-            if (!declaration.OperatorToken.IsKind(SyntaxKind.EqualsEqualsToken))
-            {
-                return;
-            }
-
-            if (declaration.Parent is StructDeclarationSyntax)
-            {
-                return;
-            }
-
-            if (!(declaration.Parent is ClassDeclarationSyntax classDeclaration))
+            if (declaration.OperatorToken.IsKind(SyntaxKind.EqualsEqualsToken)
+               && declaration.Parent is ClassDeclarationSyntax classDeclaration
+               && !classDeclaration.ChildNodes()
+                      .OfType<OperatorDeclarationSyntax>()
+                      .Any(op => op.OperatorToken.IsKind(SyntaxKind.PlusToken)
+                                 || op.OperatorToken.IsKind(SyntaxKind.MinusToken))
+               && analysisContext.SemanticModel.GetDeclaredSymbol(classDeclaration) is { } namedTypeSymbol
+               && !namedTypeSymbol.ImplementsAny(InterfacesRelyingOnOperatorEqualOverload))
             {
-                return;
+                analysisContext.ReportIssue(Diagnostic.Create(Rule, declaration.OperatorToken.GetLocation()));
             }
-
-            var hasAdditionOrSubstractionOverload =
-                classDeclaration.ChildNodes()
-                                .OfType<OperatorDeclarationSyntax>()
-                                .Any(op => op.OperatorToken.IsKind(SyntaxKind.PlusToken) ||
-                                           op.OperatorToken.IsKind(SyntaxKind.MinusToken));
-            if (hasAdditionOrSubstractionOverload)
-            {
-                return;
-            }
-
-            var namedTypeSymbol = analysisContext.SemanticModel.GetDeclaredSymbol(classDeclaration);
-            if (namedTypeSymbol == null ||
-                namedTypeSymbol.ImplementsAny(InterfacesRelyingOnOperatorEqualOverload))
-            {
-                return;
-            }
-
-            analysisContext.ReportIssue(Diagnostic.Create(rule, declaration.OperatorToken.GetLocation()));
         }
     }
 }

analyzers/src/SonarAnalyzer.Common/Helpers/KnownType.cs

@@ -337,6 +337,7 @@ internal sealed partial class KnownType
         internal static readonly KnownType System_NotSupportedException = new("System.NotSupportedException");
         internal static readonly KnownType System_Nullable_T = new("System.Nullable", "T");
         internal static readonly KnownType System_NullReferenceException = new("System.NullReferenceException");
+        internal static readonly KnownType System_Numerics_IEqualityOperators_TSelf_TOther_TResult = new("System.Numerics.IEqualityOperators", "TSelf", "TOther", "TResult");
         internal static readonly KnownType System_Object = new("System.Object");
         internal static readonly KnownType System_ObsoleteAttribute = new("System.ObsoleteAttribute");
         internal static readonly KnownType System_OutOfMemoryException = new("System.OutOfMemoryException");

analyzers/tests/SonarAnalyzer.UnitTest/Rules/DotNotOverloadOperatorEqualTest.cs → analyzers/tests/SonarAnalyzer.UnitTest/Rules/DoNotOverloadOperatorEqualTest.cs

@@ -23,25 +23,25 @@
 namespace SonarAnalyzer.UnitTest.Rules
 {
     [TestClass]
-    public class DotNotOverloadOperatorEqualTest
+    public class DoNotOverloadOperatorEqualTest
     {
-        private readonly VerifierBuilder builder = new VerifierBuilder<DotNotOverloadOperatorEqual>();
+        private readonly VerifierBuilder builder = new VerifierBuilder<DoNotOverloadOperatorEqual>();
 
         [TestMethod]
-        public void DotNotOverloadOperatorEqual() =>
-            builder.AddPaths("DotNotOverloadOperatorEqual.cs").Verify();
+        public void DoNotOverloadOperatorEqual() =>
+            builder.AddPaths("DoNotOverloadOperatorEqual.cs").Verify();
 
 #if NET
 
         [TestMethod]
-        public void DotNotOverloadOperatorEqual_CSharp9() =>
-            builder.AddPaths("DotNotOverloadOperatorEqual.CSharp9.cs")
+        public void DoNotOverloadOperatorEqual_CSharp9() =>
+            builder.AddPaths("DoNotOverloadOperatorEqual.CSharp9.cs")
                 .WithOptions(ParseOptionsHelper.FromCSharp9)
                 .Verify();
 
         [TestMethod]
-        public void DotNotOverloadOperatorEqual_CSharp11() =>
-            builder.AddPaths("DotNotOverloadOperatorEqual.CSharp11.cs")
+        public void DoNotOverloadOperatorEqual_CSharp11() =>
+            builder.AddPaths("DoNotOverloadOperatorEqual.CSharp11.cs")
                 .WithOptions(ParseOptionsHelper.FromCSharp11)
                 .Verify();
 

analyzers/tests/SonarAnalyzer.UnitTest/TestCases/DotNotOverloadOperatorEqual.CSharp11.cs → analyzers/tests/SonarAnalyzer.UnitTest/TestCases/DoNotOverloadOperatorEqual.CSharp11.cs

@@ -4,7 +4,7 @@ namespace Tests.Diagnostics
 {
     class MyClass : IEqualityOperators<MyClass, MyClass, MyClass>
     {
-        public static MyClass operator ==(MyClass? left, MyClass? right) => new MyClass(); // Noncompliant FP (implementing IEqualityOperators interface require == operator overload)
+        public static MyClass operator ==(MyClass? left, MyClass? right) => new MyClass(); // Compliant 
 
         public static MyClass operator !=(MyClass? left, MyClass? right) => new MyClass();
     }