Deprecated the `PlaygroundQuickLook` enum and `CustomPlaygroundQuickLookable`
protocol. These are being targeted for removal in Swift 5, so we want to
unconditionally deprecate them now to encourage use of
`CustomPlaygroundDisplayConvertible` instead.
This commit includes deprecated the various `CustomPlaygroundQuickLookable`
conformances across the standard library and overlay libraries.
As a temporary workaround for SR-5206, certain Foundation types which had custom behavior in JSONEncoder and JSONDecoder were granted special knowledge of those types internally in order to preserve strategies on encode/decode.
This replaces that special knowledge with a more general-purpose fix that works for all types and all encoders/decoders.
One of the limitations of not having conditional conformance at the
moment is that the implementation of `init(from:)` and `encode(to:)` on
types which require it is that failure to cast dependent types to
`Encodable` or `Decodable` is a runtime failure. There is no way to
statically guarantee that the wrapped type is `Encodable` or
`Decodable`.
As such, in those implementations, at best we can directly call
`(element as! Encodable).encode(to: encoder)`, or similar. However, this
encodes the element directly into an encoder, without giving the encoder
a chance to intercept the type. This is problematic for `JSONEncoder`
because it cannot apply a strategy if it doesn't get to intercept the
type.
This gives a temporary workaround for JSON strategies because of
internal Foundation knowledge.
This avoids indirection by making calls directly to the C implementations which prevents potentials of mismatched intent or changes of calling convention of @_silgen. The added benefit is that all of the shims in this case are no longer visible symbols (anyone using them was not authorized out side of the Foundation overlay). Also the callout methods in the headers now all share similar naming shcemes for easier refactoring and searching in the style of __NS<class><action> style. The previous compiled C/Objective-C source files were built with MRR the new headers MUST be ARC by Swift import rules.
The one caveat is that certain functions MUST avoid the bridge case (since they are part of the bridging code-paths and that would incur a recursive potential) which have the types erased up to NSObject * via the macro NS_NON_BRIDGED.
The remaining @_silgen declarations are either swift functions exposed externally to the rest of Swift’s runtime or are included in NSNumber.gyb which the Foundation team has other plans for removing those @_silgen functions at a later date and Data.swift has one external function left with @_silgen which is blocked by a bug in the compiler which seems to improperly import that particular method as an inline c function.
From the Swift documentation:
"If you define an optional variable without providing a default value,
the variable is automatically set to nil for you."
All generic bridgeable types can bridge for all their instantiations now. Removing this ferrets out some now-unnecessary traps that check for unbridgeable parameter types.
Foundation provides a number of specific operators defined in the
global scope. Push all of these into their corresponding types. This
cleanup helps verify that the SE-0091 implementation is generally
functional.
