Add test for function templates

tests/CSharp/CSharp.Tests.cs

@@ -1900,4 +1900,12 @@ public unsafe class CSharpTests
     {
         return type.GetMethods(BindingFlags.NonPublic | BindingFlags.Static).Any(x => x.Name.Contains("NativeToManaged"));
     }
+
+    [Test]
+    public void TestFunctionTemplate()
+    {
+        Assert.That(CSharpTemplates.FunctionTemplate(5.0), Is.EqualTo(5 + 4.2));
+        Assert.That(CSharpTemplates.FunctionTemplate(6f), Is.EqualTo(6 + 4.1f));
+        Assert.That(CSharpTemplates.FunctionTemplate(7), Is.EqualTo(7 + 4));
+    }
 }

tests/CSharp/CSharpTemplates.h

@@ -945,6 +945,22 @@ public:
 };
 const FloatArrayF<6> I6{ 1., 1., 1., 0., 0., 0. };
 
+template <typename T>
+DLL_API inline T FunctionTemplate(T value) {
+    if (std::is_same<T, double>::value)
+        return 4.2 + value;
+    else if (std::is_same<T, float>::value)
+        return 4.1 + value;
+    return 4 + value;
+}
+
+inline void FunctionTemplateInstantiation()
+{
+    FunctionTemplate<double>({});
+    FunctionTemplate<float>({});
+    FunctionTemplate<int>({});
+}
+
 // KEEP ORDER OTHERWISE TEST WONT WORK
 namespace IncompleteClassTemplatesTests
 {