the value buffer comes first.
The motivation for doing this is similar to the
motivation for moving it for class existentials:
it eliminates the need for an offset for the most
common accesses, which is particularly important
for the generic value witnesses.
Also try to hard-code that layout in fewer places,
or at least static_assert the places that have to
do so.
Swift SVN r16279
A useful unsafe optimization for potential implementations of Mirror that have existing heap storage to share from the value, like for Array or Dictionary.
Swift SVN r14186
Define a "Mirror" protocol with methods for querying the number of children a structured value has, getting the name and mirror for each of those children, and a string and "IDE representation" of the value, as needed by playgrounds and by our planned generic printing facility.
In the runtime, define a "reflect" function that can provide a Mirror for any object, either using a "Reflectable" protocol conformance if available, or falling back to a magic implementation in the runtime that grovels the type metadata. Stub out a bare minimum default implementation.
Swift SVN r14139
