[SR-1005] SwiftPM port to Foundation

[mxcl]

Previous ID	SR-1005
Radar	None
Original Reporter	@mxcl
Type	Task
Status	Closed
Resolution	Won't Do

Additional Detail from JIRA

Votes	0
Component/s	Package Manager
Labels	Task, StarterBug
Assignee	@ddunbar
Priority	Medium

md5: 4a38caa7b18a7e84315c664caa4922f4

relates to:

• SR-931 Make SwiftPM Path.relative(to:) solid

Issue Description:

SwiftPM was started before Foundation on Linux was mature enough for use, but this is no longer the case.

Port SwiftPM to Foundation and remove the POSIX module.

However we would prefer to keep a functional approach for eg. NSTask, so add wrappers to Utility.

[modocache]

Here's some of the work I think is involved here:

• I believe one would first need to link Foundation, which would require changes to the Utilities/bootstrap script.

• This would probably require some changes to Swift's utils/build-script-impl, in order to have the preset used for SwiftPM CI to continue to pass.

• It involves replacing a solid chunk of the SwiftPM codebase.

Between source changes and updates to the build system, I'd hesitate to recommend this as a "StarterBug" – but your bar may be set higher than mine. 🙂

[mxcl]

I classified it as Starter as it doesn't require a large understanding of the SwiftPM codebase to work on it.

Anyway, I'd like to see Foundation only used as a transitive dependency, I want to keep our high quality due to low optionality and mutable state low.

Mainly I see it being important for avoiding the edge-case plague of file system handling etc.

[Bouke]

Being a StarterBug, I've made an attempt at a partial implementation. See #284

[ddunbar]

I have posted my thoughts on what our direction should be here to:
https://lists.swift.org/pipermail/swift-build-dev/Week-of-Mon-20160509/000460.html

[ddunbar]

After seeing the impact of some of these changes, I think now the direction we want is to use Foundation for specific APIs where appropriate, versus just a general port. Closing this out, and we can consider changes on a case by case basis.