Fix RCS1085 with ref backing field

ChangeLog.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Fix analyzer [RCS1172](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1172) ([PR](https://github.com/dotnet/roslynator/pull/1710))
 - [CLI] Fix `loc` command ([PR](https://github.com/dotnet/roslynator/pull/1711))
+- Exclude ref-field backed properties from [RCS1085](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1085) ([PR](https://github.com/dotnet/roslynator/pull/1718))
 
 ## [4.14.1] - 2025-10-05
 

src/Analyzers/CSharp/Analysis/UseAutoPropertyAnalyzer.cs

@@ -108,6 +108,11 @@ private static void AnalyzePropertyDeclaration(SyntaxNodeAnalysisContext context
             return;
         }
 
+#if ROSLYN_4_4
+        if (fieldSymbol.RefKind is RefKind.Ref or RefKind.RefReadOnly)
+            return;
+#endif
+
         if (!CheckPreprocessorDirectives(property))
             return;
 

src/Tests/Analyzers.Tests/RCS1085UseAutoPropertyTests.cs

@@ -981,4 +981,30 @@ private static void Write2(ref readonly ReadOnlySequence<byte> data, IBufferWrit
     }
 }");
     }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.UseAutoProperty)]
+    public async Task TestNoDiagnostic_BackingFieldRef()
+    {
+        await VerifyNoDiagnosticAsync(
+            @"
+public ref struct Example(ref int value1, ref int value2)
+{
+    private ref int _value1 = ref value1;
+    private readonly ref int _value2 = ref value2;
+
+    public int Value1
+    {
+        get => _value1;
+        set => _value1 = value;
+    }
+
+    public int Value2
+    {
+        get => _value2;
+        set => _value2 = value;
+    }
+}
+"
+        );
+    }
 }