Swift 4 support

[thebluepotato]

What changes:

• Replaces import CSQLite with the new import SQLite3 directly exposed to Swift code.
• Updates the project to Swift 4.0, with recommended warning and a slightly edited map syntax regarding tuples.
• All the .modulemap files have been removed since they are no longer necessary.

The aim of this PR is to have code that compiles without issues with Swift 4/Xcode 9. All tests pass, except for those regarding SQLCipher, which haven't been tested. pod lib lint fails due to errors relating to SQLCipher. My guess is that there needs to be some tweaking on how SQLCipher is imported in Swift now that there's a native access to the SQLite API.

[thebluepotato]

That's the issue in #664 : the map closure take one tuple argument instead of its components. That's new in Swift 4, see SE-0110.

[jberkel]

Thanks for getting the ball rolling. Hope travis will release a new Xcode image soon.

[thebluepotato]

So actually Travis succeeds, the only fails are in the validator schemes where there's some kind of timeout. The same commit has succeeded in Travis for my own branch : https://travis-ci.org/thebluepotato/SQLite.swift/builds/248984684.
I think we could merge into the swift 4 branch.

[abunur]

I updated my Podfile as such:
pod 'SQLite.swift', :git => 'https://github.com/stephencelis/SQLite.swift.git', :branch => 'swift-4'
but I am still getting that error 'sys/_symbol_aliasing.h' file not found

any thoughts?

thanks

[thebluepotato]

@abunur Well that's because the swift-4 branch hasn't been updated yet. That's why there's this pull request. We just need someone with write access to merge the PR.
In the meantime, use pod 'SQLite.swift, :git => 'https://github.com/thebluepotato/SQLite.swift.git', :branch => 'swift-4'
Btw, I forgot to mention that the Travis builds now work because there is an Xcode 9 image now.

[abunur]

@thebluepotato lol my bad sorry :)

[abunur]

@thebluepotato so after switching to your branch, doing a pod install --repo-update
and an option-clean in Xcode, I am still getting the same error. Any other steps I need to do? Running Xcode 9 Beta 2.

[thebluepotato]

@abunur I've tried switching to the latest release, pod update, build (the error showed up) then switching back to my branch, pod update and build (no error).
I'd suggest making sure that your Podfile is correct, saved before pod update and if the error still shows up, deintegrate Cocoapods using pod deintegrate or pod superdeintegrate and finally running pod installagain.

[jberkel]

@thebluepotato thanks! looks like there aren't any massive changes in swift4. and the simulator test instability bug is back...

[thebluepotato]

@jberkel Indeed, when I closed and reopened the PR yesterday to trigger a rebuild, Travis worked completely but merging the most recent commit from mastertriggered another build which did fail here on the PR but worked on my branch...
Indeed, Swift 4 introduces mostly incremental changes. It's designed to be mostly source code compatible with Swift 3. The new stricter difference between single-tuple and multiple arguments is one of the changes that needed some adjustment.