box expression is bad

[Louis-J]

i want to return an int as object in my function, but i got several false results

YConstantExpression yconstant0 = new YConstantExpression(0, typeof(int));
YExpression.TypeAs(YExpression.Box(yconstant0), typeof(object)) // Fatal error. System.AccessViolationException: Attempted to read or write protected memory.
YExpression.Convert(YExpression.Box(yconstant0), typeof(object)) // Fatal error. System.AccessViolationException: Attempted to read or write protected memory.
YExpression.Convert(YExpression.Box(yconstant0), typeof(object), true) // Fatal error. System.AccessViolationException: Attempted to read or write protected memory.
YExpression.TypeAs(yconstant0, typeof(object)) // Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
YExpression.Convert(yconstant0, typeof(object)) // Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
YExpression.Convert(yconstant0, typeof(object), true) // got a null object
YExpression.Box(yconstant0) // Fatal error. System.AccessViolationException: Attempted to read or write protected memory.

os: win10 x64
dotnet: net6.0 x64
code:

static Func<int, object> TestFib()
{
    var ymethod = YExpression.Lambda<Func<int, object>>(
        "ymethod",
        YExpression.Condition(
            // if (n < 2)
            ynParamI0 < yconstant2,
            // return n;
            // YExpression.TypeAs(YExpression.Box(ynParamI0), typeof(object)),
            // YExpression.Convert(YExpression.Box(ynParamI0), typeof(object)),
            // YExpression.TypeAs(ynParamI0, typeof(object)),
            // YExpression.Convert(ynParamI0, typeof(object)),

            // YExpression.TypeAs(YExpression.Box(yconstant0), typeof(object)),
            // YExpression.Convert(YExpression.Box(yconstant0), typeof(object)),
            // YExpression.Convert(YExpression.Box(yconstant0), typeof(object), true),
            // YExpression.TypeAs(yconstant0, typeof(object)),
            // YExpression.Convert(yconstant0, typeof(object)),
            // YExpression.Convert(yconstant0, typeof(object), true),
            YExpression.Box(yconstant0),

            // new YConstantExpression(0, typeof(object)),

            // else return (int)method(n - 1) + (int)method(n - 2);
            YExpression.TypeAs(
                YExpression.Unbox(YExpression.Invoke(ymethodInvokeIO, ynParamI0 - yconstant1), typeof(int)) +
                    YExpression.Unbox(YExpression.Invoke(ymethodInvokeIO, ynParamI0 - yconstant2), typeof(int)),
                typeof(object)
            )
        ),
        ynParamI0
    );
    var ypackExpr = YExpression.Lambda<Func<Func<int, object>>>(
        "ypackExpr",
        YExpression.Block(
            // Func<int, object> fibC0 = null;
            new[] { ymethodInvokeIO }.AsSequence(),
            YExpression.Assign(ymethodInvokeIO, ymethod),
            ymethodInvokeIO
        )
    );
    return ypackExpr.CompileWithNestedLambdas()();
}

[ackava]

TypeAs only works for object type, it will not work for value types such as int, you cannot write a as int.

However, your YExpression.Unbox will anyway give you int, you have to use Box again as shown below.

            // else return (int)method(n - 1) + (int)method(n - 2);
            // Use Box, not TypeAs
            YExpression.Box(
                YExpression.Unbox(YExpression.Invoke(ymethodInvokeIO, ynParamI0 - yconstant1), typeof(int)) +
                    YExpression.Unbox(YExpression.Invoke(ymethodInvokeIO, ynParamI0 - yconstant2), typeof(int)),
            )