[DO NOT MERGE] Make Swift 3 / 4 consistent with SE-0054.

[rudkx]

As with Swift 5 mode, make Swift 3 / 4 reject IUOs in places where they are not allowed according to SE-0054.

[DougGregor]

Looks like there were only two issues! RxSwift had this:

print(convertResponseToString(data, response, error as NSError!, interval))

which has been fixed in the upstream repository already.

Alamofire has this:

if let encodingName = response?.textEncodingName as CFString!, convertedEncoding == nil {

where the '!' is effectively unnecessary. The code is still there upstream at https://github.com/Alamofire/Alamofire/blob/master/Source/ResponseSerialization.swift#L371

[rudkx]

Yup. It looks like we give a working fix-it in both cases as well (replace ! with ?).

[slavapestov]

@rudkx One alternative is to emit this as a warning in Swift 3/4 mode, and continue parsing as if it were a ?.

[rudkx]

@slavapestov Yes I mentioned that possibility in another forum. I think that's a reasonable choice for these casts, but probably not for something like [Int!] where other errors will surface and it will be even more confusing than just rejecting [Int!] in the first place.

[rudkx]

@swift-ci Please smoke test

[rudkx]

@swift-ci Please test source compatibility

[rudkx]

Updated this commit since cef6c94 is now in, which addresses some bugs in the earlier commit.

This is now limited to switching over to using the new tests all the time.

I still do not plan on merging this without further investigation, but want to verify where things stand and fix up any remaining code in our tree (e.g. in tests) that I may have missed.

[rudkx]

@swift-ci Please smoke test

[rudkx]

There is still a cast in Foundation that is disallowed by SE-0054. I opened swiftlang/swift-corelibs-foundation#1300 to make it a cast to Optional instead.

[rudkx]

@swift-ci Please smoke test

[rudkx]

Ran into a couple more casts in Foundation that need to be fixed up: swiftlang/swift-corelibs-foundation#1303

[rudkx]

@swift-ci Please test source compatibility

[rudkx]

@swift-ci Please smoke test Linux platform

[rudkx]

@swift-ci Please test source compatibility

[rudkx]

Please test with following pull request:
#12682
swiftlang/swift-corelibs-foundation#1306

@swift-ci Please smoke test

[rudkx]

@shahmishal Any idea what might have happened here? The multi-PR test doesn't seem to have actually started.

[shahmishal]

This is was during CI outage yesterday.

Please test with following pull request:
#12682
swiftlang/swift-corelibs-foundation#1306

@swift-ci Please smoke test

[shahmishal]

Also, it does not support same repository :(
Right now you can only provide one PR per repositories

[rudkx]

Closing in favor of a new PR I will open soon.