Array.Empty correct implementation and test added.

Author: iskiselev

JSIL.Libraries/Includes/Bootstrap/Core/Classes/System.Array.js

@@ -176,7 +176,19 @@ JSIL.ImplementExternals("System.Array", function ($) {
   $.Method({ Static: true, Public: true }, "Empty",
     new JSIL.MethodSignature($jsilcore.TypeRef("System.Array", ["!!0"]), [], ["T"]),
     function Empty(T) {
-      return [];
+      return $jsilcore.System.Array_EmptyArray$b1.Of(T).Value;
     }
   );
-});
+});
+
+
+JSIL.MakeStaticClass("System.Array+EmptyArray`1", false, ["T"], function($) {
+  $.Field({ Static: true, Public: true, ReadOnly: true }, "Value", $jsilcore.TypeRef("System.Array", [$.GenericParameter("T")]));
+
+  $.Method({ Static: true, Public: false }, ".cctor",
+    JSIL.MethodSignature.Void,
+    function EmptyArray$b1__cctor() {
+      this.Value = JSIL.Array.New(this.T, 0);
+    }
+  );
+});

Tests/SimpleTestCases/ArrayEmpty.cs

@@ -0,0 +1,30 @@
+using System;
+
+public static class Program {
+    public static void Main (string[] args)
+    {
+        var emptyObj1 = Array.Empty<object>();
+        var emptyObj2 = Array.Empty<object>();
+        var intObj1 = Array.Empty<int>();
+        var intObj2= Array.Empty<int>();
+
+        Console.WriteLine(emptyObj1.GetType());
+        Console.WriteLine(intObj1.GetType());
+        Console.WriteLine(emptyObj1 == emptyObj2 ? "true" : "false");
+        Console.WriteLine(intObj1 == intObj2 ? "true" : "false");
+        Console.WriteLine(Equals(emptyObj1, intObj1) ? "true" : "false");
+    }
+}
+
+public static class A
+{
+    public static T[] Empty<T>()
+    {
+        return EmptyArray<T>.Value;
+    }
+
+    internal static class EmptyArray<T>
+    {
+        public static readonly T[] Value = new T[0];
+    }
+}

Tests/SimpleTests.csproj

@@ -134,6 +134,7 @@
     <None Include="SimpleTestCases\ReflectionPositionalGenericNames_Issue509.cs" />
     <None Include="SimpleTestCases\ArrayType.cs" />
     <None Include="SimpleTestCases\Issue844.cs" />
+    <None Include="SimpleTestCases\ArrayEmpty.cs" />
     <Compile Include="SimpleTests.cs" />
     <None Include="SimpleTestCases\BaseAutoProperties.cs" />
     <None Include="SimpleTestCases\OverloadedVirtualMethods.cs" />