Link this and base keyword expressions to their type

The override modifier already navigates to the overridden member and
constructor initializers link this/base to the invoked constructor, but
the primary expressions carried no reference at all. Matching IDE
go-to-definition behavior, 'this' now references the current type and
'base' the base type; both directions are added together deliberately,
linking only 'base' would make the two keywords behave inconsistently.

Assisted-by: Claude:claude-fable-5:Claude Code

ICSharpCode.Decompiler/Output/TextTokenWriter.cs

@@ -283,6 +283,17 @@ namespace ICSharpCode.Decompiler
 					output.WriteReference(member, keyword);
 					return;
 				}
+				// As primary expressions, 'this' and 'base' reference the current and the
+				// base type respectively, matching IDE go-to-definition behavior.
+				if (nodeStack.Peek() is ThisReferenceExpression or BaseReferenceExpression)
+				{
+					var type = ((Expression)nodeStack.Peek()).GetResolveResult().Type;
+					if (type.Kind != TypeKind.Unknown)
+					{
+						output.WriteReference(type, keyword);
+						return;
+					}
+				}
 			}
 			// Make the 'override' modifier a reference to the nearest overridden member,
 			// so that go-to-definition on 'override' navigates to the base member.

ILSpy.Tests/TextView/KeywordReferenceTests.cs

@@ -0,0 +1,107 @@
+// Copyright (c) 2026 Siegfried Pammer
+//
+// 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.Linq;
+
+using ICSharpCode.Decompiler;
+using ICSharpCode.Decompiler.CSharp;
+using ICSharpCode.Decompiler.CSharp.OutputVisitor;
+using ICSharpCode.Decompiler.CSharp.Syntax;
+using ICSharpCode.Decompiler.TypeSystem;
+
+using ICSharpCode.ILSpy.TextView;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.ILSpy.Tests.TextView;
+
+/// <summary>
+/// Pins which keywords the C# output links as navigable references:
+/// 'this' and 'base' primary expressions reference the current and base type,
+/// and the 'override' modifier references the overridden base member.
+/// </summary>
+[TestFixture]
+public class KeywordReferenceTests
+{
+	AvaloniaEditTextOutput output = null!;
+	string text = null!;
+
+	[OneTimeSetUp]
+	public void Setup()
+	{
+		var fileName = GetType().Assembly.Location;
+		var decompiler = new CSharpDecompiler(fileName, new DecompilerSettings());
+		var syntaxTree = decompiler.DecompileType(new FullTypeName(typeof(KeywordDerived).FullName!));
+		syntaxTree.AcceptVisitor(new InsertParenthesesVisitor { InsertParenthesesForReadability = true });
+		var settings = new DecompilerSettings();
+		output = new AvaloniaEditTextOutput();
+		var tokenWriter = new ICSharpCode.Decompiler.TextTokenWriter(output, settings);
+		syntaxTree.AcceptVisitor(new CSharpOutputVisitor(tokenWriter, settings.CSharpFormattingOptions));
+		text = output.GetText();
+	}
+
+	[Test]
+	public void BaseKeywordReferencesTheBaseType()
+	{
+		var reference = ReferencesFor("base").Select(r => r.Reference).OfType<IType>().FirstOrDefault();
+		Assert.That(reference, Is.Not.Null, "the 'base' keyword must carry a type reference");
+		Assert.That(reference!.Name, Is.EqualTo(nameof(KeywordBase)));
+	}
+
+	[Test]
+	public void ThisKeywordReferencesTheCurrentType()
+	{
+		var reference = ReferencesFor("this").Select(r => r.Reference).OfType<IType>().FirstOrDefault();
+		Assert.That(reference, Is.Not.Null, "the 'this' keyword must carry a type reference");
+		Assert.That(reference!.Name, Is.EqualTo(nameof(KeywordDerived)));
+	}
+
+	[Test]
+	public void OverrideModifierReferencesTheOverriddenMember()
+	{
+		var reference = ReferencesFor("override").Select(r => r.Reference).OfType<IMember>().FirstOrDefault();
+		Assert.That(reference, Is.Not.Null, "the 'override' modifier must carry a member reference");
+		Assert.That(reference!.DeclaringTypeDefinition!.Name, Is.EqualTo(nameof(KeywordBase)));
+	}
+
+	System.Collections.Generic.IEnumerable<ReferenceSegment> ReferencesFor(string keyword)
+	{
+		return output.References.Where(r => text.Substring(r.StartOffset, r.Length) == keyword);
+	}
+}
+
+public class KeywordBase
+{
+	public virtual void TestMethod() => throw new NotImplementedException();
+}
+
+public class KeywordDerived : KeywordBase
+{
+	public int TestField;
+
+	public override void TestMethod()
+	{
+		base.TestMethod();
+	}
+
+	public void Assign(int TestField)
+	{
+		this.TestField = TestField;
+	}
+}