Fix for linker errors

Author: captainsafia

src/Components/Forms/src/FieldIdentifier.cs

@@ -126,7 +126,7 @@ private static void ParseAccessor<T>(Expression<Func<T>> accessor, out object mo
                         // so, given that it embeds captured values such as "this". We could consider special-casing
                         // for "() => something.Member" and building a cache keyed by "something.GetType()" with values
                         // of type Func<object, object> so we can cheaply map from "something" to "something.Member".
-                        var modelLambda = Expression.Lambda(memberExpression.Expression);
+                        var modelLambda = Expression.Lambda(typeof(Func<object?>), memberExpression.Expression);
                         var modelLambdaCompiled = (Func<object?>)modelLambda.Compile();
                         var result = modelLambdaCompiled() ??
                             throw new ArgumentException("The provided expression must evaluate to a non-null value.");
@@ -201,7 +201,7 @@ static Func<object, object> CreateAccessor((Type model, MemberInfo member) arg)
     private static object GetModelFromIndexer(Expression methodCallExpression)
     {
         object model;
-        var methodCallObjectLambda = Expression.Lambda(methodCallExpression!);
+        var methodCallObjectLambda = Expression.Lambda(typeof(Func<object?>), methodCallExpression!);
         var methodCallObjectLambdaCompiled = (Func<object?>)methodCallObjectLambda.Compile();
         var result = methodCallObjectLambdaCompiled();
         if (result is null)

src/SignalR/server/Core/src/DynamicHub.cs

@@ -1,11 +1,13 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics.CodeAnalysis;
 namespace Microsoft.AspNetCore.SignalR;
 
 /// <summary>
 /// A base class for SignalR hubs that use <c>dynamic</c> to represent client invocations.
 /// </summary>
+[RequiresDynamicCode("DynamicHub requires dynamic code generation to construct a call site.")]
 public abstract class DynamicHub : Hub
 {
     private DynamicHubClients? _clients;

src/SignalR/server/Core/src/DynamicHubClients.cs

@@ -1,13 +1,15 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.AspNetCore.SignalR.Internal;
 
 namespace Microsoft.AspNetCore.SignalR;
 
 /// <summary>
 /// A class that provides <c>dynamic</c> access to connections, including the one that sent the current invocation.
 /// </summary>
+[RequiresDynamicCodeAttribute("DynamicHubClient requires dynamic code generation to construct a call site.")]
 public class DynamicHubClients
 {
     private readonly IHubCallerClients _clients;

src/SignalR/server/Core/src/Internal/DynamicClientProxy.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics.CodeAnalysis;
 using System.Dynamic;
 
 namespace Microsoft.AspNetCore.SignalR.Internal;
@@ -9,6 +10,7 @@ internal sealed class DynamicClientProxy : DynamicObject
 {
     private readonly IClientProxy _clientProxy;
 
+    [RequiresDynamicCodeAttribute("This constructor requires dynamic code generation to construct a call site.")]
     public DynamicClientProxy(IClientProxy clientProxy)
     {
         _clientProxy = clientProxy;