Closure in async lambda throw InvalidOperationException

The following snippet throws InvalidOperationException with message Cannot close over byref parameter '' referenced in lambda ''

        var lambda = CodeGenerator.AsyncLambda<Func<Task<string>>>(_ =>
        {
            var hello = CodeGenerator.DeclareVariable<string>("hello");
            var foo = CodeGenerator.DeclareVariable<Func<string>>("foo");
            CodeGenerator.Statement(Expression.Assign(hello, Expression.Constant("hello")));
            CodeGenerator.Statement(Expression.Assign(foo, Expression.Lambda<Func<string>>(hello)));
            CodeGenerator.Return(Expression.Invoke(foo));
        });

        var compiled = lambda.Compile();

I want to use the AsyncLambda to generate async code from my own DSL but I havn’t been able to work around the above issue yet.

[sakno]

A new package has been published: https://www.nuget.org/packages/DotNext.Metaprogramming/4.7.5

[Cooke]

@sakno it works as expected. Thank you.