The previous documentation was not accurate. It said that the length of
the error returned would be the length of the valid prefix. In case of
no valid prefix however the code will still return 1, contrary to the
documentation.
I fixed the documentation by adding the guarantee that the error length
will always be positive and removing the information about the valid
prefix as we might want to change the precise algorithm in the future.
When we are looking for the specific type for a protocol conformance (e.g.,
because we may have a subclass of the type that declared conformances), don't
go back through swift_conformsToProtocol() multiple times, which
requires more lookups in the global conformance table. Instead, use
the (known) protocol conformance descriptor.
Previously, they would forward their unused spare bits to be used by other multi-payload enums, but
did not implement anything for single-payload extra inhabitants.
These should be audited since some might not actually need to be
@inlinable, but for now:
- Anything public and @inline(__always) is now also @inlinable
- Anything @usableFromInline and @inline(__always) is now @inlinable
When a type in keypath metadata is non-dependent, use a mangled type name
rather than a symbolic reference to an accessor function.
Part of rdar://problem/38038799.
Switch key path metadata over to mangled names for each of the places it
refers to either a type metadata accessor or a witness table accessor. For
now, the mangled name is a symbolic reference to the existing accessors.
Part of rdar://problem/38038799.
- Remove __SwiftNativeNSEnumerator from the ABI. (It’s only used in internal classes and in the Objective-C runtime.)
- Remove inlinability of init() and deinit for all the __SwiftNativeNSFoo superclasses except Array’s and Data’s.
This restores the ability to build the standard library and the tools in two
separate build invocations. This is required to cross-compile the standard
library on various targets without building complete toolchains.
The current representation of an associated conformance in a witness
tables (e.g., Iterator: IteratorProtocol within a witness table for
Sequence) is a function that the client calls.
Replace this with something more like what we do for associated types:
an associated conformance is either a pointer to the witness table (once
it is known) or a pointer to a mangled name that describes that
conformance. On first access, demangle the mangled name and replace the
entry with the resulting witness table. This will give us a more compact
representation of associated conformances, as well as always caching
them.
For now, the mangled name is a sham: it’s a mangled relative reference to
the existing witness table accessors, not a true mangled name. In time,
we’ll extend the support here to handle proper mangled names.
Part of rdar://problem/38038799.
Previously, the stdlib provided:
- getters for AnyKeyPath and PartialKeyPath, which have remained;
- a getter for KeyPath, which still exists alongside a new read
coroutine; and
- a pair of owned mutable addressors that provided modify-like behavior
for WritableKeyPath and ReferenceWritableKeyPath, which have been
replaced with modify coroutines and augmented with dedicated setters.
SILGen then uses the most efficient accessor available for the access
it's been asked to do: for example, if it's been asked to produce a
borrowed r-value, it uses the read accessor.
Providing a broad spectrum of accessor functions here seems acceptable
because the code-size hit is fixed-size: we don't need to generate
extra code per storage declaration to support more alternatives for
key paths.
Note that this is just the compiler ABI; the implementation is still
basically what it was. That means the implementation of the setters
and the read accessor is pretty far from optimal. But we can improve
the implementation later; we can't improve the ABI.
The coroutine accessors have to be implemented in C++ and used via
hand-rolled declarations in SILGen because it's not currently possible
to declare independent coroutine accessors in Swift.
Because this feature mostly exists for the standard library, turn it on
specifically. This avoids having to serialize it in the flags necessary
for parseable interfaces.
Those attributes were generated automatically, but are not needed.
All the annotated declarations are only used stdlib internally
rdar://problem/45927899
