Revert "Implement FileManager.url{s,}(for:…) and NSSearchPathForDirectoriesInDomains."

[rudkx]

Reverts #1456

[rudkx]

@swift-ci Please test

[millenomi]

Let's revert for now. I guess we need to conditionalize the use of @testable import to debug configurations only.

[millenomi]

My aim is, whenever a revert is generated, to write a postmortem to show what occurred.

A while ago in the discussion for #1456 we asked @shahmishal to change our build process on CI to build Foundation in the debug configuration (build-script --debug-foundation ), and we made conditional to that configuration the use of -enable-testing during the Foundation build. This enables the use of @testable import.

Unfortunately, this change is set up only on the Foundation PR CI testing and not on other CI setups. This made it fail when running tests as part of other CI configurations. This is correct as we would like validation testing to run on the binary that's actually built the way we would like to distribute it (that is, a Release binary).

I think the long-term solution here is to have a --build-foundation-testable-import flag in build-script, and that all CI configurations that run tests do so with that flag set to true, whether Foundation is built debug or release. That is:

Command line invocation	Optimization settings	@testable import available
--foundation	Release	No
--debug-foundation	Debug	Yes
--foundation --build-foundation-testable-import true	Release	Yes
--debug-foundation --build-foundation-testable-import false	Debug	No

For now, I'm going to pipe down to the Swift build whether @testable import is available or not, and keep its enabledness as it is (on for Debug, off for Release), and we can tackle adding the flag and changing CI later in the game so that all tests are run on CI regardless of Debug-ness.

[rudkx]

Thanks so much for the write-up. I think that's an excellent process to follow and appreciate the explanation.