Fix #6640

src/NetAnalyzers/Core/Microsoft.CodeQuality.Analyzers/ApiDesignGuidelines/OperatorOverloadsHaveNamedAlternates.Fixer.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
 
 using System.Collections.Generic;
 using System.Collections.Immutable;

src/NetAnalyzers/Core/Microsoft.CodeQuality.Analyzers/ApiDesignGuidelines/OperatorOverloadsHaveNamedAlternates.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
 
 using System.Collections.Generic;
 using System.Collections.Immutable;
@@ -99,7 +99,7 @@ private static void AnalyzeSymbol(SymbolAnalysisContext symbolContext)
                     // don't report a diagnostic on the `op_False` method because then the user would see two diagnostics for what is really one error
                     // special-case looking for `IsTrue` instance property
                     // named properties can't be overloaded so there will only ever be 0 or 1
-                    IPropertySymbol property = typeSymbol.GetMembers(IsTrueText).OfType<IPropertySymbol>().FirstOrDefault();
+                    IPropertySymbol property = ClassHierarchy(typeSymbol).SelectMany(x => x.GetMembers(IsTrueText).OfType<IPropertySymbol>()).FirstOrDefault();
                     if (property == null || property.Type.SpecialType != SpecialType.System_Boolean)
                     {
                         symbolContext.ReportDiagnostic(CreateDiagnostic(PropertyRule, GetSymbolLocation(methodSymbol), AddAlternateText, IsTrueText, operatorName));
@@ -125,7 +125,7 @@ private static void AnalyzeSymbol(SymbolAnalysisContext symbolContext)
                         unmatchedMethods.Add(expectedGroup.AlternateMethod2);
                     }
 
-                    foreach (IMethodSymbol candidateMethod in typeSymbol.GetMembers().OfType<IMethodSymbol>())
+                    foreach (IMethodSymbol candidateMethod in ClassHierarchy(typeSymbol).SelectMany(x => x.GetMembers().OfType<IMethodSymbol>()))
                     {
                         if (candidateMethod.Name == expectedGroup.AlternateMethod1 || candidateMethod.Name == expectedGroup.AlternateMethod2)
                         {
@@ -168,6 +168,15 @@ private static void AnalyzeSymbol(SymbolAnalysisContext symbolContext)
             }
         }
 
+        private static IEnumerable<ITypeSymbol> ClassHierarchy(ITypeSymbol typeSymbol)
+        {
+            while (typeSymbol is not null)
+            {
+                yield return typeSymbol;
+                typeSymbol = typeSymbol.BaseType;
+            }
+        }
+
         private static Location GetSymbolLocation(ISymbol symbol)
         {
             return symbol.OriginalDefinition.Locations.First();

src/NetAnalyzers/UnitTests/Microsoft.CodeQuality.Analyzers/ApiDesignGuidelines/OperatorOverloadsHaveNamedAlternatesTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
 
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.Testing;
@@ -68,6 +68,24 @@ public class C
 ");
         }
 
+        [Fact]
+        public Task HasAlternateMethodOnBaseClass_CSharpAsync()
+        {
+            return VerifyCS.VerifyAnalyzerAsync(@"
+public class B
+{
+    public static D Add(D left, D right) { return new D(); }
+    public bool IsTrue => true;
+}
+
+public class D : B
+{
+    public static D operator +(D left, D right) { return new D(); }
+    public static bool operator true(D d) => true;
+    public static bool operator false(D d) => false;
+}");
+        }
+
         [Fact]
         public async Task HasMultipleAlternatePrimary_CSharpAsync()
         {