Linq Select throws exception (ValueTuple?) issue?

[yggdrasil-tynor]

context.AddVariable("list1", new int[] { 1, 2, 3, 8 });
context.AddVariable("list2", new int[] { 4, 5, 6, 7 });
var test = context.Evaluate("list1.Cast<int>().Select<int, int>((item, i) => item - list1[i]).Cast<int>().Sum()");

throws:

ExpressionEvaluatorSyntaxErrorException : The call of the method "Sum" on type [System.Linq.Enumerable+SelectArrayIterator`2[System.Int32,System.Int32]] generate this error : Index was outside the bounds of the array.

With Zip or EquiZip it works fine:

list1.Cast<int>().EquiZip<int, int, int>(list2, (l1, l2) => l1 + l2).Cast<int>().Sum()"

What is wrong with select?

[yggdrasil-tynor]

EDIT: Seems like it's an issue when using ValueTuple.... Maybe this is not supported?

Here is a simple .NET fiddle example which shows the unexpected behaviour:

[yggdrasil-tynor]

This line breaks it:

ExpressionEvaluator/CodingSeb.ExpressionEvaluator/ExpressionEvaluator.cs

Line 3425 in 365551a

vars[argsNames[a]] = args[a];

For some reason the internalDelegate args contains 1 item, and should contain 2 in this case...

ExpressionEvaluator/CodingSeb.ExpressionEvaluator/ExpressionEvaluator.cs

Lines 3504 to 3516 in 365551a

	// For Linq methods that are overloaded and implement possibly lambda arguments
	try
	{
	if (methodInfos.Count > 1
	&& type == typeof(Enumerable)
	&& args.Count == 2
	&& args[1] is InternalDelegate internalDelegate
	&& args[0] is IEnumerable enumerable
	&& enumerable.GetEnumerator() is IEnumerator enumerator
	&& enumerator.MoveNext()
	&& methodInfos.Any(m => m.GetParameters().Any(p => p.ParameterType.Name.StartsWith("Func"))))
	{
	Type lambdaResultType = internalDelegate.Invoke(enumerator.Current).GetType();

I guess this overload requires some special handling?

[yggdrasil-tynor]

FYI this is still an issue in 1.5.0-alpha releases