Module erased

Erased: the referent of a type-erased reference.

Some std types hold a value whose type only the generic code that stored it knows: a Waker's task, a Task's argument, a widget's click-handler context. SafeC has no trait objects, so such a type keeps a typed function and its context as '?&Erased' / 'fn R(?&Erased, ...)' fields, written only by a generic constructor that takes the matching 'fn R(?&T, ...)' and '?&T' — so every call through the erased pair is well-typed — and read back by calling the function with its context:

generic<T> struct Waker Waker::new(fn void(?&T, unsigned long) wake, ?&T data, unsigned long tag);
...
self.wake_(self.data_, self.tag_);   // calls wake(data, tag) as T

Erasing (T -> Erased) is a cast inside 'unsafe' in that constructor; nothing outside it ever turns an Erased back into a T. An Erased is never constructed: it only appears behind a reference. This replaces C's untyped userdata pointer everywhere in std.