fn rebase(r: *Io.Reader, capacity: usize) Io.Reader.RebaseError!void
fn rebase(r: *Io.Reader, capacity: usize) Io.Reader.RebaseError!void { const fr: *File.Reader = @alignCast(@fieldParentPtr("interface", r)); const context: *Context = @fieldParentPtr("fr", fr); try fillUntimed(context, capacity); }