Introduce narrow support for tuple/tuple dynamic casts that merely add
or remove labels, but require the element types to match exactly. This
gets us back to allowing the same correct dynamic casts as in Swift
3.0, when labels were completely ignored.
id-as-Any lets you pass Optional to an ObjC API that takes `nonnull id`, and also lets you bridge containers of `Optional` to `NSArray` etc. When this occurs, we can unwrap the value and bridge it so that inhabited optionals still pass into ObjC in the expected way, but we need something to represent `none` other than the `nil` pointer. Cocoa provides `NSNull` as the canonical "null for containers" object, which is the least bad of many possible answers. If we happen to have the rare nested optional `T??`, there is no precedented analog for these in Cocoa, so just generate a unique sentinel object to preserve the `nil`-ness depth so we at least don't lose information round-tripping across the ObjC-Swift bridge.
Making Optional conform to _ObjectiveCBridgeable is more or less enough to make this all work, though there are a few additional edge case things that need to be fixed up. We don't want to accept `AnyObject??` as an @objc-compatible type, so special-case Optional in `getForeignRepresentable`.
Implements SR-0140 (rdar://problem/27905315).
id-as-Any lets you pass Optional to an ObjC API that takes `nonnull id`, and also lets you bridge containers of `Optional` to `NSArray` etc. When this occurs, we can unwrap the value and bridge it so that inhabited optionals still pass into ObjC in the expected way, but we need something to represent `none` other than the `nil` pointer. Cocoa provides `NSNull` as the canonical "null for containers" object, which is the least bad of many possible answers. If we happen to have the rare nested optional `T??`, there is no precedented analog for these in Cocoa, so just generate a unique sentinel object to preserve the `nil`-ness depth so we at least don't lose information round-tripping across the ObjC-Swift bridge.
Making Optional conform to _ObjectiveCBridgeable is more or less enough to make this all work, though there are a few additional edge case things that need to be fixed up. We don't want to accept `AnyObject??` as an @objc-compatible type, so special-case Optional in `getForeignRepresentable`.
Implements SR-0140 (rdar://problem/27905315).
This affects the computed stride for fixed-sized types in IRGen as well as the stored stride in value witness tables.
The reason is to let comparisons and difference operations work for pointers to zero-sized types.
(Currently this is achieved by using Builtin.strideof_nonzero in MemoryLayout.stride, but this requires a std::max(1, stride) operation after loading the stride)
Provide default implementations for all of the CustomNSError requirements:
* errorDomain: default to the name of the enum type
* errorCode: default to the same thing "_code" gets, e.g., the enum tag or
raw value
* errorUserInfo: default to empty
This makes it significantly easier to customize just one aspect of the
NSError view of an error type, e.g., just the user-info dictionary,
without having to write boilerplate for the others. This was actually
part of SE-0112, but I missed it in the original implementation and we
thought it was an amendment.
Fixes rdar://problem/23511842.
IIRC we never had any evidence that the performance impact of a
separate allocator here was actually measurable, and it does come
at a significant fragmentation cost because every single cache
allocates at least a page of memory. Sharing that with the system
allocator makes more sense, even if these allocations are typically
permanent.
This also means that standard memory-debugging tools will actually
find problems with out-of-bounds accesses to metadata.
MetadataCache's allocator into it.
The major functional change here is that MetadataCache will now use
the slab allocator for tree nodes, but I also switched the Hashable
conformances cache to use ConcurrentMap directly instead of a
Lazy<ConcurrentMap<>>.
Previously, these were all using MetadataCache. MetadataCache is a
more heavyweight structure which acquires a lock before building the
metadata. This is appropriate if building the metadata is very
expensive or might have semantic side-effects which cannot be rolled
back. It's also useful when there's a risk of re-entrance, since it
can diagnose such things instead of simply dead-locking or infinitely
recursing. However, it's necessary for structural cases like tuple
and function types, and instead we can just use ConcurrentMap, which
does a compare-and-swap to publish the constructed metadata and
potentially destroys it if another thread successfully won the race.
This is an optimization which we could not previously attempt.
As part of this, fix tuple metadata uniquing to consider the label
string correctly. This exposes a bug where the runtime demangling
of tuple metadata nodes doesn't preserve labels; fix this as well.
be an ObjC class wrapper.
Fixes a longstanding bug that was exposed by my metadata cache improvements;
previously it was hidden due to a chain of coincidences around the
allocation of ObjCClassWrapper metadata.
Previously, these were all using MetadataCache. MetadataCache is a
more heavyweight structure which acquires a lock before building the
metadata. This is appropriate if building the metadata is very
expensive or might have semantic side-effects which cannot be rolled
back. It's also useful when there's a risk of re-entrance, since it
can diagnose such things instead of simply dead-locking or infinitely
recursing. However, it's necessary for structural cases like tuple
and function types, and instead we can just use ConcurrentMap, which
does a compare-and-swap to publish the constructed metadata and
potentially destroys it if another thread successfully won the race.
This is an optimization which we could not previously attempt.
As part of this, fix tuple metadata uniquing to consider the label
string correctly. This exposes a bug where the runtime demangling
of tuple metadata nodes doesn't preserve labels; fix this as well.
Rather than having Sema provide a default implementation of
Error._code when needed, introduce a runtime function to extract the
default code, so that we can provide a default implementation via a
protocol extension in the standard library.
When getting a mirror child that is a class existential, there
may be witness tables for the protocol composition to copy. Don't
just take the address of a class instance pointer from the stack -
make a temporary existential-like before calling into the Mirror
constructor.
This now correctly covers reflecting weak optional class types, and weak
optional class existential types, along with fixing a stack buffer
overflow reported by the Address Sanitizer (thanks, ASan!).
Tests were also updated to check for the validity of the child's data.
rdar://problem/27348445
Heap boxes don't have a "class" metadata kind, so make
sure to release them when creating a new owner for loading
weak references in the runtime mirrors.
rdar://problem/27348445
