I can't get this to reproduce with anything more self-contained,
unfortunately: it seems that IntegerLiteralConvertible is the interesting
protocol, and the type has to come from the standard library.
Swift SVN r25294
...rather than trying to serialize them again, which could lead to attempting
to cross-reference an ExtensionDecl, which can't be done.
rdar://problem/19794141
Swift SVN r25292
Most tests were using %swift or similar substitutions, which did not
include the target triple and SDK. The driver was defaulting to the
host OS. Thus, we could not run the tests when the standard library was
not built for OS X.
Swift SVN r24504
That is, if we need a type MyIndex<T> to be a valid ForwardIndex, we should
be able to find it in the conformance for BidirectionalIndex, which inherits
from ForwardIndex.
<rdar://problem/15484898>
Swift SVN r11270
