1 files changed, 108 insertions, 0 deletions
diff --git a/tests/src/JIT/Regression/JitBlue/GitHub_12392/GitHub_12392.cs b/tests/src/JIT/Regression/JitBlue/GitHub_12392/GitHub_12392.cs
new file mode 100644
index 0000000000..23058fd768
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/GitHub_12392/GitHub_12392.cs
@@ -0,0 +1,108 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Reflection;
+
+namespace Test
+{
+    // This is a regression test for a bug in fgMorphRecognizeBoxNullable.
+    // See the comment in Setting<T>.HasValue for details.
+    class Program
+    {
+
+        static int Main(string[] args)
+        {
+            Test t = new Test();
+            if (!t.TestMethod())
+            {
+                Console.WriteLine("SUCCESS");
+                return 100;
+            }
+            else
+            {
+                Console.WriteLine("FAILURE");
+                return 0;
+            }
+        }
+    }
+
+    class Test
+    {
+        Setting<bool?> supportInteractive = Setting.ForBool(null);
+
+        public bool TestMethod()
+        {
+            return this.supportInteractive.HasValue;
+        }
+    }
+
+    public class Setting<T>
+    {
+        Setting()
+        {
+        }
+
+        public Setting(T value)
+        {
+            this.value = value;
+        }
+
+        public bool HasValue
+        {
+            get
+            {
+                if (this.value != null)
+                {
+                    Type t = this.value.GetType();
+                    if (t.IsGenericType)
+                    {
+                        if (t.GetGenericTypeDefinition() == typeof(Nullable<>))
+                        {
+                            PropertyInfo hasValueProperty = t.GetProperty("HasValue");
+                            bool result = (bool)hasValueProperty.GetValue(this.value, null);
+                            return result;
+                        }
+                    }
+                }
+
+                // The bug reproduces when the C# compiler generates
+                //   ldnull
+                //   cgt.un
+                //   ret
+                // for this statement.
+                // The code above this statement is necessary so that some assertions are
+                // propagated and the statement gets re-morphed.
+                // The bug in fgMorphRecognizeBoxNullable was that it couldn't deal
+                // with a morphed helper call correctly.
+                return null != this.value;
+            }
+        }
+
+        T value;
+        public T Value
+        {
+            get { return this.value; }
+            set { this.value = value; }
+        }
+    }
+
+    public class Setting
+    {
+        Setting()
+        {
+            ;
+        }
+
+        public static Setting<bool?> ForBool(string parameter)
+        {
+            if (null == parameter)
+            {
+                return new Setting<bool?>(null);
+            }
+            Setting<bool?> setting = new Setting<bool?>(bool.Parse(parameter));
+            return setting;
+        }
+    }
+}