Feature: allow interception of any generic method call when using Arg.AnyType

src/NSubstitute/Core/CallInfo.cs

@@ -1,12 +1,13 @@
-using System.Diagnostics.CodeAnalysis;
 using NSubstitute.Exceptions;
+using System.Diagnostics.CodeAnalysis;
+using System.Reflection;
 
 // Disable nullability for entry-point API
 #nullable disable annotations
 
 namespace NSubstitute.Core;
 
-public class CallInfo(Argument[] callArguments)
+public class CallInfo(Argument[] callArguments, MethodInfo methodInfo)
 {
 
     /// <summary>
@@ -25,6 +26,8 @@ public object this[int index]
         }
     }
 
+    public MethodInfo MethodInfo => methodInfo;
+
     private void EnsureArgIsSettable(Argument argument, int index, object value)
     {
         if (!argument.IsByRef)

src/NSubstitute/Core/CallInfoFactory.cs

@@ -5,7 +5,7 @@ public class CallInfoFactory : ICallInfoFactory
     public CallInfo Create(ICall call)
     {
         var arguments = GetArgumentsFromCall(call);
-        return new CallInfo(arguments);
+        return new CallInfo(arguments, call.GetMethodInfo());
     }
 
     private static Argument[] GetArgumentsFromCall(ICall call)

src/NSubstitute/Core/CallSpecification.cs

@@ -1,5 +1,5 @@
-using System.Reflection;
 using NSubstitute.Core.Arguments;
+using System.Reflection;
 
 namespace NSubstitute.Core;
 
@@ -93,7 +93,7 @@ internal static bool TypesAreAllEquivalent(Type[] aArgs, Type[] bArgs)
     private static bool AreEquivalentDefinitions(MethodInfo a, MethodInfo b)
     {
         return a.IsGenericMethod == b.IsGenericMethod
-               && a.ReturnType == b.ReturnType
+               && TypesAreAllEquivalent([a.ReturnType], [b.ReturnType])
                && a.Name.Equals(b.Name, StringComparison.Ordinal);
     }