Swift version specific rules

[jonah-williams]

Do you all have thoughts about how to manage sets of rules which are Swift 2.3 or Swift 3.0 specific?

Given Xcode 8 supporting both Swift versions how might we allow developers using SwiftLint to specify which set of rules should apply to a specific project? We could maintain rules with different names and include and exclude them individually but that's not a great interface to work with.

Should we specify the swift version as part of of our .swiftlint.yml? Could we resolve this at the same time as #221 by specifying a version of the ruleset to apply?

[jpsim]

SwiftLint works against any Swift version after 1.0, and will resolve the Swift version to use in the following order:

• $XCODE_DEFAULT_TOOLCHAIN_OVERRIDE
• $TOOLCHAIN_DIR
• xcrun -find swift
• /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain
• /Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain
• ~/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain
• ~/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain

That being said, I'm not aware of any rule that semantically should behave differently across Swift versions other than the change that came in #660.

If you can think of other rules that might need to behave differently with Swift 3, please let us know!

[jpsim]

As of #1081, we can detect the current Swift version and adjust rule behavior based on that.