Previously often times when casting a value, we would just pass along the
cleanup of the uncasted value. With semantic SIL this is no longer correct since
the cleanup now needs to be on the cast result.
This caused problems for certain usages of Builtin.castToNativeObject(...) by
the stdlib. Specifically, the stdlib was using this on AnyObject values that
were not necessarily native. Since we were recreating the cleanup on the native
value, a swift native release was being used =><=.
In this commit I solve this problem by:
1. Adding an assert in Builtin.castToNativeObject(...) that ensures that any value
passed to Builtin.castToNativeObject() is known conservatively to use swift
native reference counting.
2. I changed all uses where we do not have a precondition of a native ref
counting type to use Builtin.castToUnknownObject(...).
3. I added a new Builtin called Builtin.unsafeCastToNativeObject(...) that does
not have the compile time check. I used this to rewrite callsites in the stdlib
where we know via preconditions that an AnyObject will dynamically always be
native.
rdar://29791263
In various cases where we had global operators for non-generic
concrete types (such as String + String), move those operators into
the type. This should not affect the sources, but makes the exposition
of the library cleaner.
Plus, it's a good test for the compiler, which uncovered a few issues
where the compiler was coupled with the library.
Allow 'static' (or, in classes, final 'class') operators to be
declared within types and extensions thereof. Within protocols,
require operators to be marked 'static'. Use a warning with a Fix-It
to stage this in, so we don't break the world's code.
Protocol conformance checking already seems to work, so add some tests
for that. Update a pile of tests and the standard library to include
the required 'static' keywords.
There is an amusing name-mangling change here. Global operators were
getting marked as 'static' (for silly reasons), so their mangled names
had the 'Z' modifier for static methods, even though this doesn't make
sense. Now, operators within types and extensions need to be 'static'
as written.
