Add a bookmarks feature for the decompiled C# view

ICSharpCode.ILSpyX/Settings/ILSpySettings.cs

@@ -18,7 +18,6 @@
 
 using System;
 using System.IO;
-using System.Threading;
 using System.Xml;
 using System.Xml.Linq;
 
@@ -129,34 +128,5 @@ static string GetConfigFile()
 		}
 
 		const string ConfigFileMutex = "01A91708-49D1-410D-B8EB-4DE2662B3971";
-
-		/// <summary>
-		/// Helper class for serializing access to the config file when multiple ILSpy instances are running.
-		/// </summary>
-		sealed class MutexProtector : IDisposable
-		{
-			readonly Mutex mutex;
-
-			public MutexProtector(string name)
-			{
-				this.mutex = new Mutex(true, name, out bool createdNew);
-				if (createdNew)
-					return;
-
-				try
-				{
-					mutex.WaitOne();
-				}
-				catch (AbandonedMutexException)
-				{
-				}
-			}
-
-			public void Dispose()
-			{
-				mutex.ReleaseMutex();
-				mutex.Dispose();
-			}
-		}
 	}
 }

ICSharpCode.ILSpyX/Settings/MutexProtector.cs

@@ -0,0 +1,55 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Threading;
+
+namespace ICSharpCode.ILSpyX.Settings
+{
+	/// <summary>
+	/// Guards a config-file read-modify-write with a named <see cref="Mutex"/> so that two ILSpy
+	/// instances editing the same sidecar (the settings XML, the bookmark list, ...) fold their
+	/// changes in turn instead of overwriting each other. Acquire it around the
+	/// read-update-write block and dispose it to release.
+	/// </summary>
+	public sealed class MutexProtector : IDisposable
+	{
+		readonly Mutex mutex;
+
+		public MutexProtector(string name)
+		{
+			this.mutex = new Mutex(true, name, out bool createdNew);
+			if (createdNew)
+				return;
+
+			try
+			{
+				mutex.WaitOne();
+			}
+			catch (AbandonedMutexException)
+			{
+			}
+		}
+
+		public void Dispose()
+		{
+			mutex.ReleaseMutex();
+			mutex.Dispose();
+		}
+	}
+}

ILSpy.Tests/AppEnv/ConfigurationFilesTests.cs

@@ -0,0 +1,62 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.IO;
+
+using AwesomeAssertions;
+
+using ICSharpCode.ILSpy.AppEnv;
+using ICSharpCode.ILSpyX.Settings;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.ILSpy.Tests.AppEnv;
+
+// ConfigurationFiles.GetPath underpins where the dock layout and the bookmark list are
+// stored: as JSON sidecars in the same directory as ILSpy.xml. These tests pin that
+// "next to the settings file" contract and the headless fallback.
+[TestFixture]
+public class ConfigurationFilesTests
+{
+	Func<string>? savedProvider;
+
+	[SetUp]
+	public void SaveProvider() => savedProvider = ILSpySettings.SettingsFilePathProvider;
+
+	[TearDown]
+	public void RestoreProvider() => ILSpySettings.SettingsFilePathProvider = savedProvider;
+
+	[Test]
+	public void GetPath_returns_sidecar_in_settings_directory()
+	{
+		var settingsDir = Path.Combine(Path.GetTempPath(), "ILSpyConfigTest");
+		ILSpySettings.SettingsFilePathProvider = () => Path.Combine(settingsDir, "ILSpy.xml");
+
+		ConfigurationFiles.GetPath("ILSpy.Bookmarks.json")
+			.Should().Be(Path.Combine(settingsDir, "ILSpy.Bookmarks.json"));
+	}
+
+	[Test]
+	public void GetPath_falls_back_to_bare_name_when_provider_is_absent()
+	{
+		ILSpySettings.SettingsFilePathProvider = null;
+
+		ConfigurationFiles.GetPath("ILSpy.Bookmarks.json").Should().Be("ILSpy.Bookmarks.json");
+	}
+}

ILSpy.Tests/Bookmarks/BookmarkAnchoringTests.cs

@@ -0,0 +1,82 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System.Linq;
+using System.Threading.Tasks;
+
+using AvaloniaEdit.Document;
+
+using Avalonia.Headless.NUnit;
+
+using AwesomeAssertions;
+
+using ICSharpCode.Decompiler;
+using ICSharpCode.ILSpy.AppEnv;
+using ICSharpCode.ILSpy.Bookmarks;
+using ICSharpCode.ILSpy.Languages;
+using ICSharpCode.ILSpy.TextView;
+using ICSharpCode.ILSpy.TreeNodes;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.ILSpy.Tests.Bookmarks;
+
+// End-to-end anchoring against real decompiled output: a statement line yields a body anchor,
+// a definition line yields a token anchor, and a comment line yields nothing.
+[TestFixture]
+public class BookmarkAnchoringTests
+{
+	[AvaloniaTest]
+	public async Task Decompiled_type_offers_both_body_and_token_anchors()
+	{
+		var (_, vm) = await TestHarness.BootAsync(3);
+		var csharp = AppComposition.Current.GetExport<LanguageService>().Languages.First(l => l.Name == "C#");
+
+		var asm = vm.AssemblyTreeModel.FindNode<AssemblyTreeNode>("System.Linq");
+		var typeSystem = asm!.LoadedAssembly.GetTypeSystemOrNull();
+		var type = typeSystem!.MainModule.TypeDefinitions.First(t => t.FullName == "System.Linq.Enumerable");
+
+		var output = new AvaloniaEditTextOutput();
+		csharp.DecompileType(type, output, new DecompilationOptions(new DecompilerSettings()));
+
+		var document = new TextDocument(output.GetText());
+		var debugInfo = new DecompiledDebugInfo(output.MethodDebugInfos);
+
+		Bookmark? body = null, token = null;
+		for (int line = 1; line <= document.LineCount; line++)
+		{
+			var bookmark = BookmarkAnchoring.CreateForLine(debugInfo, output.References, document, line);
+			if (bookmark?.Kind == BookmarkKind.Body)
+				body ??= bookmark;
+			else if (bookmark?.Kind == BookmarkKind.Token)
+				token ??= bookmark;
+		}
+
+		body.Should().NotBeNull("statement lines must produce a body anchor");
+		token.Should().NotBeNull("definition lines must produce a token anchor");
+
+
+		// Line 1 is the "// <assembly name>" comment: neither a statement nor a definition,
+		// so it falls back to the visible line in the current decompiled document.
+		var fallback = BookmarkAnchoring.CreateForLine(debugInfo, output.References, document, 1, type);
+		fallback.Should().NotBeNull();
+		fallback!.Kind.Should().Be(BookmarkKind.Line);
+		fallback.LineNumber.Should().Be(1);
+		fallback.Token.Should().Be((uint)System.Reflection.Metadata.Ecma335.MetadataTokens.GetToken(type.MetadataToken));
+	}
+}

ILSpy.Tests/Bookmarks/BookmarkContextMenuTests.cs

@@ -0,0 +1,138 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+
+using Avalonia.Headless.NUnit;
+using Avalonia.Threading;
+
+using AvaloniaEdit.Document;
+
+using AwesomeAssertions;
+
+using ICSharpCode.ILSpy;
+using ICSharpCode.ILSpy.AppEnv;
+using ICSharpCode.ILSpy.Bookmarks;
+using ICSharpCode.ILSpy.Properties;
+using ICSharpCode.ILSpy.TextView;
+using ICSharpCode.ILSpy.TreeNodes;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.ILSpy.Tests.Bookmarks;
+
+[TestFixture]
+public class BookmarkContextMenuTests
+{
+	[AvaloniaTest]
+	public async Task Toggle_Bookmark_Entry_Acts_On_The_Right_Clicked_Line_Not_The_Caret()
+	{
+		var (window, vm) = await TestHarness.BootAsync(3);
+		var manager = AppComposition.Current.GetExport<BookmarkManager>();
+		manager.Clear();
+
+		var coreLibName = typeof(object).Assembly.GetName().Name!;
+		var typeNode = vm.AssemblyTreeModel.FindNode<TypeTreeNode>(coreLibName, "System", "System.Object");
+		vm.AssemblyTreeModel.SelectNode(typeNode);
+		await vm.DockWorkspace.WaitForDecompiledTextAsync();
+
+		var view = await window.WaitForComponent<DecompilerTextView>();
+		for (int i = 0; i < 8; i++)
+		{
+			Dispatcher.UIThread.RunJobs();
+			await Task.Delay(25);
+		}
+
+		var bookmarkableLines = Enumerable.Range(1, view.Editor.Document.LineCount)
+			.Where(view.CanToggleBookmarkAtLine)
+			.Take(2)
+			.ToArray();
+		bookmarkableLines.Should().HaveCount(2, "two distinct bookmarkable lines are needed to tell the caret from the click");
+
+		int caretLine = bookmarkableLines[0];
+		int clickedLine = bookmarkableLines[1];
+		view.Editor.TextArea.Caret.Offset = view.Editor.Document.GetLineByNumber(caretLine).Offset;
+		int clickedOffset = view.Editor.Document.GetLineByNumber(clickedLine).Offset;
+
+		var toggle = AppComposition.Current.GetExport<ContextMenuEntryRegistry>()
+			.GetEntry(nameof(Resources.BookmarkToggle));
+		toggle.Execute(new TextViewContext { TextView = view, TextLocation = clickedOffset });
+		Dispatcher.UIThread.RunJobs();
+
+		manager.Bookmarks.Should().ContainSingle();
+		view.GetLineForBookmark(manager.Bookmarks[0]).Should().Be(clickedLine);
+		manager.Bookmarks[0].LocationNodeName.Should().Be("System.Object");
+	}
+
+	[AvaloniaTest]
+	public async Task Navigation_Does_Not_Fall_Back_To_Entity_When_Saved_Tree_Path_Is_Missing()
+	{
+		var (window, vm) = await TestHarness.BootAsync(3);
+		var manager = AppComposition.Current.GetExport<BookmarkManager>();
+		manager.Clear();
+
+		var coreLibName = typeof(object).Assembly.GetName().Name!;
+		var objectNode = vm.AssemblyTreeModel.FindNode<TypeTreeNode>(coreLibName, "System", "System.Object");
+		vm.AssemblyTreeModel.SelectNode(objectNode);
+		await vm.DockWorkspace.WaitForDecompiledTextAsync();
+
+		var view = await window.WaitForComponent<DecompilerTextView>();
+		for (int i = 0; i < 8; i++)
+		{
+			Dispatcher.UIThread.RunJobs();
+			await Task.Delay(25);
+		}
+
+		int line = Enumerable.Range(1, view.Editor.Document.LineCount)
+			.First(view.CanToggleBookmarkAtLine);
+		int offset = view.Editor.Document.GetLineByNumber(line).Offset;
+		AppComposition.Current.GetExport<ContextMenuEntryRegistry>()
+			.GetEntry(nameof(Resources.BookmarkToggle))
+			.Execute(new TextViewContext { TextView = view, TextLocation = offset });
+		Dispatcher.UIThread.RunJobs();
+
+		manager.Bookmarks.Should().ContainSingle();
+		var bookmark = manager.Bookmarks[0];
+		bookmark.ViewState.Should().NotBeNull();
+		bookmark.ViewState = bookmark.ViewState! with { SelectedTreeNodePath = new[] { "Missing assembly", "Missing type" } };
+
+		var stringNode = vm.AssemblyTreeModel.FindNode<TypeTreeNode>(coreLibName, "System", "System.String");
+		vm.AssemblyTreeModel.SelectNode(stringNode);
+
+		await AppComposition.Current.GetExport<BookmarkNavigator>().NavigateToAsync(bookmark);
+
+		((object?)vm.AssemblyTreeModel.SelectedItem).Should().BeSameAs(stringNode);
+	}
+
+	[AvaloniaTest]
+	public async Task Queued_Bookmark_Scroll_Ignores_A_Replaced_Document()
+	{
+		var (window, _) = await TestHarness.BootAsync(3);
+		var view = await window.WaitForComponent<DecompilerTextView>();
+		view.Editor.Document = new TextDocument(string.Join("\n", Enumerable.Range(1, 30).Select(i => $"line {i}")));
+
+		var scrollToLine = typeof(DecompilerTextView).GetMethod("ScrollToLine", BindingFlags.Instance | BindingFlags.NonPublic);
+		scrollToLine.Should().NotBeNull();
+		scrollToLine!.Invoke(view, new object?[] { 20, null });
+
+		view.Editor.Document = new TextDocument("replacement");
+		Dispatcher.UIThread.RunJobs();
+	}
+}