Make sure we build the CatchStmt and DoCatchStmt AST nodes when
code-completing inside the body of a catch so that we can complete the
bindings from the catch.
It's often a good idea to early-exit once we see a code completion
token, but not when we skip building an AST node that provides variable
bindings. In code completion, we don't have Scope-based lookup, and
rely on having reachable AST nodes for patterns so that we can dig the
out the bindings we need.
Also extend the pattern checking to handle "IsPattern", since we
apparently weren't handling "let x as Foo", and that affects all complex
catch patterns because of an implicit "as ErrorType" or explicit
"as NSError".
rdar://problem/21116164
Swift SVN r29070
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
It's not okay to filter to only ErrorType results, since we may be
trying to chain to an error type result foo.bar.getError(). And the
existing logic had no way to handle results from other modules, so we
were missing key results like 'NSError'.
Eventually we'll want to bring back something like this that handles all
modules, but as a way to bump the priority of ErrorType results rather
than to filter out everything else.
rdar://problem/20985515
Swift SVN r28716
When the code completion token appears after throw keyword,
a set of visible decls and instances conforming _ErrorType are
recommended as completion.
Swift SVN r26565
