From 69b5962ccdb91e5078c00c1ba90d068b1ac06bef Mon Sep 17 00:00:00 2001
From: Josef Pihrt <josef@pihrt.net>
Date: Wed, 8 May 2024 20:17:53 +0200
Subject: [PATCH] Fix analyzer RCS1085 (#1461)

---
 ChangeLog.md                                  |  1 +
 .../Analysis/UseAutoPropertyAnalyzer.cs       |  2 +-
 .../RCS1085UseAutoPropertyTests.cs            | 29 +++++++++++++++++++
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/ChangeLog.md b/ChangeLog.md
index f279354439..1b9117d4ab 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fix analyzer [RCS1246](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1246) ([PR](https://github.com/dotnet/roslynator/pull/1460))
+- Fix analyzer [RCS1085](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1085) ([PR](https://github.com/dotnet/roslynator/pull/1461))
 
 ## [4.12.2] - 2024-04-23
 
diff --git a/src/Analyzers/CSharp/Analysis/UseAutoPropertyAnalyzer.cs b/src/Analyzers/CSharp/Analysis/UseAutoPropertyAnalyzer.cs
index 422e2e1b58..16db72c43d 100644
--- a/src/Analyzers/CSharp/Analysis/UseAutoPropertyAnalyzer.cs
+++ b/src/Analyzers/CSharp/Analysis/UseAutoPropertyAnalyzer.cs
@@ -486,7 +486,7 @@ public override void VisitArgument(ArgumentSyntax node)
         {
             CancellationToken.ThrowIfCancellationRequested();
 
-            if (node.RefOrOutKeyword.IsKind(SyntaxKind.RefKeyword, SyntaxKind.OutKeyword))
+            if (node.RefOrOutKeyword.IsKind(SyntaxKind.RefKeyword, SyntaxKind.OutKeyword, SyntaxKind.InKeyword))
             {
                 ExpressionSyntax expression = node.Expression?.WalkDownParentheses();
 
diff --git a/src/Tests/Analyzers.Tests/RCS1085UseAutoPropertyTests.cs b/src/Tests/Analyzers.Tests/RCS1085UseAutoPropertyTests.cs
index a65b724594..3b72a81dbc 100644
--- a/src/Tests/Analyzers.Tests/RCS1085UseAutoPropertyTests.cs
+++ b/src/Tests/Analyzers.Tests/RCS1085UseAutoPropertyTests.cs
@@ -952,4 +952,33 @@ class C
 }
 ");
     }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.UseAutoProperty)]
+    public async Task TestNoDiagnostic_BackingFieldUsedByReference()
+    {
+        await VerifyNoDiagnosticAsync(@"
+using System.Buffers;
+
+class Repro(ReadOnlySequence<byte> data)
+{
+    public ReadOnlySequence<byte> Data => _data;
+    private readonly ReadOnlySequence<byte> _data = data;
+
+    public void Method(IBufferWriter<byte> writer)
+    {
+        Write1(in _data, writer);
+        Write2(in _data, writer);
+    }
+
+    private static void Write1(in ReadOnlySequence<byte> data, IBufferWriter<byte> writer)
+    {
+        data.CopyTo(writer.GetSpan((int)data.Length));
+    }
+
+    private static void Write2(ref readonly ReadOnlySequence<byte> data, IBufferWriter<byte> writer)
+    {
+        data.CopyTo(writer.GetSpan((int)data.Length));
+    }
+}");
+    }
 }