Marshal.GetDelegateForFunctionPointer(IntPtr, Type) is obsolete in

netstandard

src/csharp/Grpc.Core/Internal/UnmanagedLibrary.cs

@@ -134,7 +134,11 @@ namespace Grpc.Core.Internal
             {
                 throw new MissingMethodException(string.Format("The native method \"{0}\" does not exist", methodName));
             }
-            return Marshal.GetDelegateForFunctionPointer(ptr, typeof(T)) as T;
+#if NETSTANDARD1_5
+            return Marshal.GetDelegateForFunctionPointer<T>(ptr);  // non-generic version is obsolete
+#else
+            return Marshal.GetDelegateForFunctionPointer(ptr, typeof(T)) as T;  // generic version not available in .NET45
+#endif
         }
 
         /// <summary>