MA0016 skips conversion methods

src/Meziantou.Analyzer/Rules/PreferReturningCollectionAbstractionInsteadOfImplementationAnalyzer.cs

@@ -146,6 +146,9 @@ public void AnalyzeSymbol(SymbolAnalysisContext context)
                     break;
 
                 case IMethodSymbol methodSymbol when methodSymbol.MethodKind is not MethodKind.PropertyGet and not MethodKind.PropertySet:
+                    if (context.Symbol is IMethodSymbol { MethodKind: MethodKind.Conversion })
+                        return;
+
                     if (!IsValidType(methodSymbol.ReturnType))
                     {
                         context.ReportDiagnostic(Rule, methodSymbol, DiagnosticMethodReportOptions.ReportOnReturnType);

tests/Meziantou.Analyzer.Test/Helpers/ProjectBuilder.Validation.cs

@@ -1,13 +1,5 @@
-using System;
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
-using System.Globalization;
-using System.IO;
-using System.Linq;
-using System.Text;
-using System.Threading;
-using System.Threading.Tasks;
 using Meziantou.Analyzer.Test.Helpers;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CodeActions;
@@ -17,7 +9,6 @@
 using Microsoft.CodeAnalysis.Formatting;
 using Microsoft.CodeAnalysis.Simplification;
 using Microsoft.CodeAnalysis.Text;
-using Xunit;
 
 namespace TestHelper;
 

tests/Meziantou.Analyzer.Test/Rules/PreferReturningCollectionAbstractionInsteadOfImplementationAnalyzerTests.cs

@@ -371,4 +371,44 @@ public class Test : ITest
                 """)
             .ValidateAsync();
     }
+
+    [Fact]
+    public async Task ConversionOperator()
+    {
+        await CreateProjectBuilder()
+            .WithSourceCode("""                
+                public class Sample
+                {
+                    public static implicit operator Sample(System.Collections.Generic.List<string> _) => throw null;
+                    public static implicit operator System.Collections.Generic.List<string>(Sample _) => throw null;
+                }
+                """)
+            .ValidateAsync();
+    }
+
+    [Fact]
+    public async Task AddOperator()
+    {
+        await CreateProjectBuilder()
+            .WithSourceCode("""                                
+                public class Sample
+                {
+                    public static Sample operator+(Sample instance, [|System.Collections.Generic.List<int>|] value) => throw null;
+                }
+                """)
+            .ValidateAsync();
+    }
+
+    [Fact]
+    public async Task AddOperator_Instance()
+    {
+        await CreateProjectBuilder()
+            .WithSourceCode("""                                
+                public class Sample : System.Collections.Generic.List<int>
+                {
+                    public static Sample operator+(Sample instance, int value) => throw null;
+                }
+                """)
+            .ValidateAsync();
+    }
 }