From c3160fe819e251b65053ec3d6c80b1ea01e7c609 Mon Sep 17 00:00:00 2001
From: Ivan Bondarev <ibond84@googlemail.com>
Date: Fri, 24 Dec 2021 15:14:40 +0100
Subject: [PATCH] #2579

---
 NETGenerator/NETGenerator.cs   | 30 +++++++++++++++++++++++++-----
 TestSuite/double_question3.pas |  8 ++++++++
 2 files changed, 33 insertions(+), 5 deletions(-)
 create mode 100644 TestSuite/double_question3.pas

diff --git a/NETGenerator/NETGenerator.cs b/NETGenerator/NETGenerator.cs
index 076be33d9..3b92f9ffa 100644
--- a/NETGenerator/NETGenerator.cs
+++ b/NETGenerator/NETGenerator.cs
@@ -10757,11 +10757,31 @@ namespace PascalABCCompiler.NETGenerator
             else
             {
                 value.condition.visit(this);
-                tmp_lb = il.DeclareLocal(helper.GetTypeReference(value.type).tp);
-                il.Emit(OpCodes.Stloc, tmp_lb);
-                il.Emit(OpCodes.Ldloc, tmp_lb);
-                il.Emit(OpCodes.Ldnull);
-                il.Emit(OpCodes.Ceq);
+                if (value.condition.type.is_nullable_type)
+                {
+                    
+                    tmp_lb = il.DeclareLocal(helper.GetTypeReference(value.type).tp);
+                    il.Emit(OpCodes.Stloc, tmp_lb);
+                    il.Emit(OpCodes.Ldloca, tmp_lb);
+                    MethodInfo mi = null;
+                    TypeInfo cond_ti = helper.GetTypeReference(value.condition.type);
+                    if (value.condition.type is IGenericTypeInstance)
+                        mi = TypeBuilder.GetMethod(cond_ti.tp, typeof(Nullable<>).GetMethod("get_HasValue"));
+                    else
+                        mi = cond_ti.tp.GetMethod("get_HasValue");
+                    il.Emit(OpCodes.Call, mi);
+                    il.Emit(OpCodes.Ldc_I4_0);
+                    il.Emit(OpCodes.Ceq);
+                }
+                else
+                {
+                    tmp_lb = il.DeclareLocal(helper.GetTypeReference(value.type).tp);
+                    il.Emit(OpCodes.Stloc, tmp_lb);
+                    il.Emit(OpCodes.Ldloc, tmp_lb);
+                    il.Emit(OpCodes.Ldnull);
+                    il.Emit(OpCodes.Ceq);
+                }
+                
             }
                 
 
diff --git a/TestSuite/double_question3.pas b/TestSuite/double_question3.pas
new file mode 100644
index 000000000..a09704683
--- /dev/null
+++ b/TestSuite/double_question3.pas
@@ -0,0 +1,8 @@
+begin
+  var i: integer?;
+  var x := i ?? 0;
+  assert(x.Value = 0);
+  i := 1;
+  x := i ?? 0;
+  assert(x.Value = 1);
+end.
\ No newline at end of file