implemented with Builtin.Word
The definition Swift.Int is becoming heavily platform-dependent, please
avoid using it in SIL and IR tests unless Swift.Int is being tested and
can't be replaced with a fixed-width type (e.g., Int32).
Swift SVN r24720
This only tackles the protocol case (<rdar://problem/17510790>); it
does not yet generalize to an arbitrary "class" requirement on either
existentials or generics.
Swift SVN r19896
In most cases this means adding @public to things that get serialized;
in a few cases it means using a modern public stdlib API instead of
a legacy thing I was trying to keep @internal.
Swift SVN r19350
