Predicate.Invoke(Predicate.Invoke(..)) does not work

[matkoerner]

ExpressionExpander.VisitMethodCall; "Invoke"-Resolver (lines 65-85) is not resolving the case that one of the direct arguments in Invoke(..) is a call to another .Invoke.

Example:

System.Linq.Expressions.Expression<Func<string, string[], IEnumerable<string>>> PredicateFoo =
    (par1, par2) => par1.Split(par2, StringSplitOptions.None); // Just some stuff

System.Linq.Expressions.Expression<Func<string, string[], IEnumerable<string>>> PredicateInnerInvoke =
    (par1, par2) => PredicateFoo.Invoke(par1, par2); // Invoke

System.Linq.Expressions.Expression<Func<string, string[], IEnumerable<string>>> PredicateOuterInvoke =
    (par1, par2) => PredicateFoo.Invoke(PredicateInnerInvoke.Invoke(par1, par2).First(), par2); // Invoke(Invoke(..))

var bad = PredicateOuterInvoke.Expand().ToString();
// bad == (par1, par2) => value(xyz+<>c__DisplayClass2).PredicateOuterInvoke.Invoke(par1, par2).First().Split(par2, None)
// There is still a call to .Invoke here; Entity Framework does not know how to handle this
// Expected (no .Invoke anymore):
// good == (par1, par2) => par1.Split(par2, None).First().Split(par2, None)

We resolved this by using the following (very simple & not correct) Expand method:

public static Expression<TDelegate> ExpandEx<TDelegate>(this Expression<TDelegate> expr)
{
    while (expr.ToString().Contains(".Invoke"))
    {
        expr = LinqKit.Extensions.Expand(expr); // Expand will not expand all .Invoke calls, so do it recursively
    }
    return expr;
}

Our real life example:
Predicate1(X) = Get all users where X
Predicate2(X) = Get all users and their deputies from (Get all users where X)
so we are calling Predicate2.Invoke(Predicate1.Invoke(X)) and this fails.