[SR-8056] UIApplication.LaunchOptionsKey migrates to UIApplication.UIApplication.LaunchOptionsKey

[keith]

Previous ID	SR-8056
Radar	rdar://problem/41350748
Original Reporter	@keith
Type	Bug

Environment

Xcode 10.0 beta 2 (10L177m)

Additional Detail from JIRA

Votes	0
Component/s	Source Tooling
Labels	Bug, Migrator
Assignee	@nkcsgexi
Priority	Medium

md5: 36fe65333275d13d9b576e1fcb364899

Issue Description:

If you create a new project in Xcode 10, and then change the SWIFT_VERSION to 4, and then migrate to Swift 4.2, it attempts to migrate this code from the template:

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

To:

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.UIApplication.LaunchOptionsKey: Any]?) -> Bool {

Instead of leaving it alone

[belkadan]

cc @nkcsgexi

[nkcsgexi]

This is not a common case because the code under migration is written in Xcode 10 already.

[belkadan]

4 to 4.2 is a valid migration even for new Xcode 10 code, though.

[nkcsgexi]

Swift 4.2 migrator is designed to update users' codebase written in Xcode 9 to Xcode 10 to incorporate SDK changes. The change from 4 to 4.2 in Xcode 10 should be minimal.

[belkadan]

That is incorrect. The SDK changes going from Xcode 9 / Swift 4 to Xcode 10 / Swift 4.2 are almost identical to those going from Xcode 10 / Swift 4 to Xcode 10 / Swift 4.2. This should not be gated on Xcode version.

[nkcsgexi]

This specific code example:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {}

It doesn't build in Xcode 9 / Swift 4 but it builds in Xcode 10 / Swift 4.

[belkadan]

That's only because we always allow using the "newest" names for types even in old language modes. An Xcode 10 / Swift 4 user is still more likely to use the previous name of UIApplicationLaunchOptionsKey.

[nkcsgexi]

That's correct. In the "more likely" cases, migrator performs correctly. The problem in this bug is about using new names in Swift 4 mode gets touched while migrating.

[nkcsgexi]

@swift-ci create

[NachoSoto]

FWIW I got the same bug without using the Migrator: the fixit made this change for me.