From 6ae8466979a566a89b1f30ab1348e995034714a0 Mon Sep 17 00:00:00 2001
From: Siegfried Pammer <siegfriedpammer@gmail.com>
Date: Sat, 4 Jul 2026 13:11:08 +0200
Subject: [PATCH] Add pretty test for exception filters with side effects

All existing filter tests only read state; a filter that mutates a
ref local observed by the handler pins the ordering between the
filter expression and the handler body.

Assisted-by: Claude:claude-fable-5:Claude Code
---
 .../TestCases/Pretty/ExceptionHandling.cs     | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/ICSharpCode.Decompiler.Tests/TestCases/Pretty/ExceptionHandling.cs b/ICSharpCode.Decompiler.Tests/TestCases/Pretty/ExceptionHandling.cs
index 090ccc71c..d564f15ff 100644
--- a/ICSharpCode.Decompiler.Tests/TestCases/Pretty/ExceptionHandling.cs
+++ b/ICSharpCode.Decompiler.Tests/TestCases/Pretty/ExceptionHandling.cs
@@ -500,6 +500,25 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 #pragma warning restore CA2200 // Rethrow to preserve stack details
 			}
 		}
+
+		private static bool FilterWithSideEffect(Exception e, ref int log)
+		{
+			log++;
+			return e.Message.Length > 0;
+		}
+
+		public static void SideEffectingFilter()
+		{
+			int log = 0;
+			try
+			{
+				Console.WriteLine("try");
+			}
+			catch (Exception e) when (FilterWithSideEffect(e, ref log))
+			{
+				Console.WriteLine(log);
+			}
+		}
 #endif
 
 		public static void ContinueInCatchInForeach(int[] arr)