checked_cast_br promises to maintain RC identity, but a cast from an ErrorType-conforming class to NSError may change the RC identity by bridging. Make sure that potential class-to-NSError casts go through the indirect cast entry points for now. The runtime implementation still needs to be fixed to handle the class-to-NSError case, but this is part of rdar://problem/21116814.
Swift SVN r29089
Then use that to ban NSError.init(), because it doesn't create a valid
NSError. In the long run Foundation will hopefully add this to their
headers, but they can't yet (rdar://problem/19977891).
rdar://problem/21042412
Swift SVN r28881
- Enable 'catch is NSError' and 'catch let e as NSError {' patterns to
a) work, and b) be considered to be exhaustive catches. This enables
people to catch an error and *use* it as an NSError directly, instead
of having to do boiler-platey cases. This is particularly important
for the migrator.
- Do not warn about non-noop coersion casts (like "_ as NSError" when
matching an ErrorType), since they provide useful type adjustment to
the subpattern. Still warn on noop ones.
- Simplify CatchStmt::isSyntacticallyExhaustive to use
Pattern::isRefutablePattern. Add a FIXME, because the parser is guiding
closure "throws" inference before the pattern is type checked, which means
that it is incorrect (but only in subtle cases).
- When diagnosing pointless 'as' patterns like:
switch 4 {
case _ as Int: break
say "'as' test is always true" instead of "'is' test is always true".
Swift SVN r28774
