Consider adding a ContractAnnotation attribute to LinqExtensions.IsNullOrEmpty<T>(this IList<T> list) to avoid a warning

[Michael Ryan]

I’m using Unity 2018.4.30 with Odin Inspector 3.0.3.0 (Editor Only) and JetBrains Rider 2021.1.5. on Windows 10 20H2.

In the following code sample, the usage of list on line 6 has a Possible ‘System.NullReferenceException’ warning generated by the code inspection.

private static Object TestMethod(IEnumerable<Object> targets)
{
   var list = targets?.ToList();
   if (!list.IsNullOrEmpty())
   {
      var count = list.Count;
   }

   return null;
}

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Compare that to the inline test of both conditions where the usage of list on line 6 does not generate any warnings.

private static Object TestMethod(IEnumerable<Object> targets)
{
   var list = targets?.ToList();
   if (!((list == null) || (list.Count == 0)))
   {
      var count = list.Count;
   }

   return null;
}

‌

I believe the Jetbrains.Annotations attributes have been embedded in all versions of Unity since 5.0.

Consider adding [JetBrains.Annotations.ContractAnnotation("null=>true", true)] to Sirenix.Utilities.LinqExtensions.IsNullOrEmpty<T>(this IList<T> list)to avoid the unnecessary “Possible NullReferenceException” warning on usages that follow the extension method call.

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https://www.jetbrains.com/help/resharper/Contract_Annotations.html

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