Implement ForeachStatement for (static) Arrays

I am currently stuck at the semantic analysis.
because depending on the type of the expression that is itterated foreach does diffrent things
how I check If the itterated type has thoose methods ?
-  `popFront()`/`front()`
-  `opApply`

What is idx useful for here ? As far as I understand, idx is reading the value of a variable and throwing it away, that do not make any sense.