We used to allow @objc enums on Linux, where Objective-C interop is disabled,
because the check first looked for an import of the Foundation module
(which could be the non-Objective-C corelibs-foundation) before checking
if Objective-C interop was enabled.
Since @objc enums don't actually depend on Foundation or Objective-C and
only have a different layout in IRGen, let's bring back and formalize the
old behavior.
Fixes https://bugs.swift.org/browse/SR-14548 / rdar://problem/77325078.
Because people put all sorts of nonsense into @objc enums (most
reasonably, "private cases", which represent valid values that are not
API), the Swift-synthesized implementation of 'hash(into:)' needs to
not expect a switch statement to be exhaustive. And since
Swift-defined @objc enums are supposed to behave enough like C-defined
enums, they should at least handle simple method calls with an invalid
raw value, which means that 'rawValue' likewise should not use a
switch.
This patch provides alternate implementations that look like this:
extension ImportedEnum {
public var rawValue: Int {
return unsafeBitCast(self, to: Int.self)
}
public func hash(into hasher: inout Hasher) {
hasher.combine(self.rawValue)
}
}
rdar://problem/41913284
