// from 
var res = RegexOptions.Compiled | RegexOptions.Singleline;
// to 
var res = (RegexOptions)((int)RegexOptions.Compiled | (int)RegexOptions.Singleline);

var target = new Interpreter();
target.Reference(typeof(RegexOptions));
target.Reference(typeof(DateTimeKind));

var result = target.Eval<RegexOptions>("RegexOptions.Compiled | RegexOptions.Singleline");
Assert.True(result.HasFlag(RegexOptions.Compiled));
Assert.True(result.HasFlag(RegexOptions.Singleline));