Add targeted regression test for #115442 (#115817)

Resolves #115442.

Author: MichalStrehovsky

src/tests/nativeaot/SmokeTests/UnitTests/Generics.cs

@@ -60,6 +60,7 @@ internal static int Run()
         Test104913Regression.Run();
         Test105397Regression.Run();
         Test105880Regression.Run();
+        Test115442Regression.Run();
         TestInvokeMemberCornerCaseInGenerics.Run();
         TestRefAny.Run();
         TestNullableCasting.Run();
@@ -3685,6 +3686,19 @@ public static void Run()
         }
     }
 
+    class Test115442Regression
+    {
+        public readonly struct TypeBuilder<T1, T2>
+        {
+            public TypeBuilder<(T1, T2), T3> Add<T3>() => default;
+        }
+
+        public static void Run()
+        {
+            typeof(TypeBuilder<int, int>).GetMethod("Add").MakeGenericMethod(typeof(int)).Invoke(default(TypeBuilder<int, int>), []);
+        }
+    }
+
     class TestInvokeMemberCornerCaseInGenerics
     {
         class Generic<T>