swift234

When importing external enum types, delay the creation of implicit members and their associated support functions until after the types are actually referenced.

This significantly reduces the amount of overhead incurred when naively importing large external modules without referencing many of its members, which should directly improve response times in the playground. For example, the repro code attached to rdar://problem/16387393 imports Foundation but references none of its members, and with these changes its total compilation time is almost 2.5x faster.

Swift SVN r15479