Bug 23687 – IFTI fails forwarding an alias to struct field

``` import std.stdio; import std.range; struct LinkedListAdaptor(alias nextField, T){ T current; @safe: nothrow: this(T head){ current = head; } bool empty() const { return current == null; } T front() { return current; } void popFront() { current = __traits(child, current, nextField); } } auto linkedListAdaptor(alias nextField, T)(T head) if(is(T == U*, U)){ return LinkedListAdaptor!(nextField, T)(head); //fails with: //onlineapp.d(27): Error: symbol or expression expected as first argument of __traits `child` instead of `Node*` // return LinkedListAdaptor!(__traits(child, T, nextField), T)(head); } struct Node{ int data; Node* next; } void main(){ Node* head = new Node(10, new Node(20, null)); auto rng1 = LinkedListAdaptor!(Node.next, Node*)(head); //OK auto rng = linkedListAdaptor!(Node.next)(head); foreach(const x; rng){ writeln(x.data); } } ``` fails on the `auto rng = linkedListAdaptor!(Node.next)(head);` line with `Error: need `this` for `linkedListAdaptor` of type `pure nothrow @nogc @safe LinkedListAdaptor!(next, Node*)(Node* head)``

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