Add VBPretty spec for VB.NET parameterized properties

C# has no syntax for named properties with parameters, so the expected
output declares the accessors as ordinary methods, keeps the
property-level attributes under the inert 'property:' attribute target
(ignored by csc with CS0657), and consumes the properties through
direct accessor calls, which Roslyn permits exactly for properties
whose shape C# cannot bind. Red against the current decompiler, which
emits a parameterless property whose body references the vanished
parameters.

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

ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -148,6 +148,7 @@
     <None Include="TestCases\VBPretty\Issue1906.vb" />
     <None Include="TestCases\VBPretty\Issue2192.vb" />
     <None Include="TestCases\VBPretty\Select.vb" />
+    <None Include="TestCases\VBPretty\ParameterizedProperties.vb" />
     <None Include="TestCases\ILPretty\Unsafe.il" />
     <None Include="TestCases\ILPretty\Issue1389.il" />
     <None Include="TestCases\ILPretty\SequenceOfNestedIfs.il" />

ICSharpCode.Decompiler.Tests/TestCases/VBPretty/ParameterizedProperties.cs

@@ -0,0 +1,68 @@
+#pragma warning disable 657
+using System;
+
+public interface IParameterized
+{
+	// C# has no syntax for parameterized properties; the accessors of
+	// property 'IndexedValue' are emitted as ordinary methods.
+	int get_IndexedValue(int index);
+	void set_IndexedValue(int index, int Value);
+}
+
+public class ParameterizedProperties : IParameterized
+{
+	private int _field;
+
+	// C# has no syntax for parameterized properties; the accessors of
+	// property 'SharedProp' are emitted as ordinary methods.
+	public static int get_SharedProp(int index)
+	{
+		return index;
+	}
+
+	public static void set_SharedProp(int index, int value)
+	{
+	}
+
+	// C# has no syntax for parameterized properties; the accessors of
+	// property 'IndexedValue' are emitted as ordinary methods.
+	public int get_IndexedValue(int index)
+	{
+		return _field;
+	}
+
+	public void set_IndexedValue(int index, int value)
+	{
+		_field = value;
+	}
+
+	// C# has no syntax for parameterized properties; the accessors of
+	// property 'ReadOnlyProp' are emitted as ordinary methods.
+	public int get_ReadOnlyProp(int index)
+	{
+		return index;
+	}
+
+	// C# has no syntax for parameterized properties; the accessors of
+	// property 'Attributed' are emitted as ordinary methods. The property's
+	// attributes are kept below under the inert 'property:' target (CS0657).
+	[property: Obsolete("read-write parameterized property")]
+	public int get_Attributed(int index)
+	{
+		return index;
+	}
+
+	public void set_Attributed(int index, int value)
+	{
+	}
+
+	public void Use()
+	{
+		ParameterizedProperties.set_SharedProp(1, 2);
+		_field = ParameterizedProperties.get_SharedProp(3);
+		this.set_IndexedValue(4, 5);
+		_field = this.get_IndexedValue(6);
+		((IParameterized)this).set_IndexedValue(7, 8);
+		_field = ((IParameterized)this).get_IndexedValue(9);
+	}
+}

ICSharpCode.Decompiler.Tests/TestCases/VBPretty/ParameterizedProperties.vb

@@ -0,0 +1,53 @@
+Imports System
+
+Public Interface IParameterized
+	Property IndexedValue(index As Integer) As Integer
+End Interface
+
+Public Class ParameterizedProperties
+	Implements IParameterized
+
+	Private _field As Integer
+
+	Public Shared Property SharedProp(index As Integer) As Integer
+		Get
+			Return index
+		End Get
+		Set(value As Integer)
+		End Set
+	End Property
+
+	Public Property IndexedValue(index As Integer) As Integer Implements IParameterized.IndexedValue
+		Get
+			Return _field
+		End Get
+		Set(value As Integer)
+			_field = value
+		End Set
+	End Property
+
+	Public ReadOnly Property ReadOnlyProp(index As Integer) As Integer
+		Get
+			Return index
+		End Get
+	End Property
+
+	<Obsolete("read-write parameterized property")>
+	Public Property Attributed(index As Integer) As Integer
+		Get
+			Return index
+		End Get
+		Set(value As Integer)
+		End Set
+	End Property
+
+	Public Sub Use()
+		SharedProp(1) = 2
+		_field = SharedProp(3)
+		IndexedValue(4) = 5
+		_field = IndexedValue(6)
+		Dim p As IParameterized = Me
+		p.IndexedValue(7) = 8
+		_field = p.IndexedValue(9)
+	End Sub
+End Class

ICSharpCode.Decompiler.Tests/VBPrettyTestRunner.cs

@@ -113,6 +113,12 @@ namespace ICSharpCode.Decompiler.Tests
 			await Run(options: options | CompilerOptions.Library);
 		}
 
+		[Test]
+		public async Task ParameterizedProperties([ValueSource(nameof(defaultOptions))] CompilerOptions options)
+		{
+			await Run(options: options | CompilerOptions.Library);
+		}
+
 		[Test]
 		public async Task Select([ValueSource(nameof(defaultOptions))] CompilerOptions options)
 		{