[release/8.0-staging] Fix analyzer crash on C# 14 extensions

src/tools/illink/src/ILLink.RoslynAnalyzer/TrimAnalysis/MethodParameterValue.cs

@@ -9,11 +9,6 @@ namespace ILLink.Shared.TrimAnalysis
 {
 	internal partial record MethodParameterValue
 	{
-		public MethodParameterValue (IParameterSymbol parameterSymbol)
-			: this (new ParameterProxy (parameterSymbol)) { }
-		public MethodParameterValue (IMethodSymbol methodSymbol, ParameterIndex parameterIndex, DynamicallyAccessedMemberTypes dynamicallyAccessedMemberTypes)
-			: this (new (new (methodSymbol), parameterIndex), dynamicallyAccessedMemberTypes) { }
-
 		public MethodParameterValue (ParameterProxy parameter)
 			: this (parameter, FlowAnnotations.GetMethodParameterAnnotation (parameter)) { }
 

src/tools/illink/src/ILLink.RoslynAnalyzer/TrimAnalysis/ParameterProxy.cs

@@ -9,10 +9,10 @@ namespace ILLink.Shared.TypeSystemProxy
 {
 	internal partial struct ParameterProxy
 	{
-		public ParameterProxy (IParameterSymbol parameter)
+		public ParameterProxy (IParameterSymbol parameter, IMethodSymbol method)
 		{
-			Method = new ((IMethodSymbol) parameter.ContainingSymbol);
-			Index = (ParameterIndex) parameter.Ordinal + (Method.HasImplicitThis () ? 1 : 0);
+			Method = new (method);
+			Index = (ParameterIndex) parameter.Ordinal + (method.HasImplicitThis () ? 1 : 0);
 		}
 
 		public partial ReferenceKind GetReferenceKind ()

src/tools/illink/src/ILLink.RoslynAnalyzer/TrimAnalysis/TrimAnalysisVisitor.cs

@@ -113,7 +113,7 @@ public override MultiValue VisitInstanceReference (IInstanceReferenceOperation i
 			// The instance reference operation represents a 'this' or 'base' reference to the containing type,
 			// so we get the annotation from the containing method.
 			if (instanceRef.Type != null && instanceRef.Type.IsTypeInterestingForDataflow ())
-				return new MethodParameterValue (Method, (ParameterIndex) 0, Method.GetDynamicallyAccessedMemberTypes ());
+				return new MethodParameterValue (new ParameterProxy (new (Method), (ParameterIndex) 0));
 
 			return TopValue;
 		}
@@ -187,7 +187,11 @@ public override MultiValue GetFieldTargetValue (IFieldSymbol field)
 
 		public override MultiValue GetParameterTargetValue (IParameterSymbol parameter)
 		{
-			return parameter.Type.IsTypeInterestingForDataflow () ? new MethodParameterValue (parameter) : TopValue;
+			// Skip analysis for extension members (we have no way to represent a parameter on an extension type).
+			if (parameter.ContainingSymbol is not IMethodSymbol method)
+				return TopValue;
+
+			return parameter.Type.IsTypeInterestingForDataflow () ? new MethodParameterValue (new ParameterProxy (parameter, method)) : TopValue;
 		}
 
 		public override void HandleAssignment (MultiValue source, MultiValue target, IOperation operation)

src/tools/illink/test/ILLink.RoslynAnalyzer.Tests/DataFlowTests.cs

@@ -131,6 +131,12 @@ public Task EventDataFlow ()
 			return RunTest ();
 		}
 
+		[Fact]
+		public Task ExtensionsDataFlow ()
+		{
+			return RunTest ();
+		}
+
 		[Fact]
 		public Task FieldDataFlow ()
 		{

src/tools/illink/test/Mono.Linker.Tests.Cases/DataFlow/ExtensionsDataFlow.cs

@@ -0,0 +1,66 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using Mono.Linker.Tests.Cases.Expectations.Assertions;
+using Mono.Linker.Tests.Cases.Expectations.Helpers;
+
+namespace Mono.Linker.Tests.Cases.DataFlow
+{
+	[SkipKeptItemsValidation]
+	[ExpectedNoWarnings]
+	public class ExtensionsDataFlow
+	{
+		public static void Main ()
+		{
+			TestExtensionMethod ();
+			TestExtensionMethodMismatch ();
+			TestExtensionMethodRequires ();
+		}
+
+		[ExpectedWarning ("IL2072", "GetWithMethods", nameof (Extensions.ExtensionMethod))]
+		static void TestExtensionMethod ()
+		{
+			GetWithFields ().ExtensionMethod ();
+			GetWithMethods ().ExtensionMethod ();
+		}
+
+		static void TestExtensionMethodMismatch ()
+		{
+			GetWithFields ().ExtensionMethodMismatch ();
+		}
+
+		[ExpectedWarning ("IL2026", nameof (Extensions.ExtensionMethodRequires))]
+		static void TestExtensionMethodRequires ()
+		{
+			GetWithFields ().ExtensionMethodRequires ();
+		}
+
+		[return: DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicFields)]
+		static Type GetWithFields () => null;
+
+		[return: DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicMethods)]
+		static Type GetWithMethods () => null;
+	}
+
+	[ExpectedNoWarnings]
+	public static class Extensions
+	{
+		public static void ExtensionMethod ([DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicFields)] this Type type)
+		{
+			type.RequiresPublicFields ();
+		}
+
+		[ExpectedWarning ("IL2067", "RequiresPublicMethods")]
+		public static void ExtensionMethodMismatch ([DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicFields)] this Type type)
+		{
+			type.RequiresPublicMethods ();
+		}
+
+		[RequiresUnreferencedCode (nameof (ExtensionMethodRequires))]
+		public static void ExtensionMethodRequires ([DynamicallyAccessedMembers (DynamicallyAccessedMemberTypes.PublicFields)] this Type type)
+		{
+		}
+	}
+}