WORKAROUND:
import std.stdio;
struct Foo {
     int val = 0;
     ~this() {
         writefln("destruct %s", val);
     }
}
void bar(ARGS...)() {
     struct Tuple {
         ARGS args;
         alias args this;
     }
     Tuple args;
     args[0].val = 1;
     writefln("val = %s", args[0].val);
}
void main() {
     bar!Foo();
}