SWIFT_VERSION breaks Carthage build

[JonasVautherin]

I am not completely sure, but it seems to me that Xcode sets SWIFT_VERSION in a way that is incompatible with swiftenv.

Say I have Swift 4.2.1 installed on my system, and I don't have Swift 4.2. Xcode doesn't care, and calls it 4.2. And it sets SWIFT_VERSION = "4.2".

Now, swiftenv reads SWIFT_VERSION (that apparently overrides .swiftenv) and tries to run with Swift 4.2 instead of 4.2.1.

It results in the following error:

swiftenv: version `4.2' (set by SWIFT_VERSION environment variable) is not installed
no such command: swift

More specifically, this means that I can build manually from Xcode, but Carthage fails to build my project. Like if Carthage was using swiftenv, but Xcode didn't care and went directly to its own Swift binary.

Uninstalling swiftenv fixed my issue.

Would there be a way to somehow improve this behavior?

[davisford]

I don't think swiftenv works with Carthage at all. The latter appears to completely ignore the former.

If I run

$ swift --version
Apple Swift version 4.2.1 (swift-4.2.1-RELEASE)

...which is set by .swiftenv but then run carthage bootstrap --platform iOS it still uses the default 5.0:

***  Skipped installing ios-snapshot-test-case.framework binary due to the error:
	"Incompatible Swift version - framework was built with 4.2.1 (swiftlang-1000.11.42 clang-1000.11.45.1) and the local version is 5.0 (swiftlang-1001.0.69.5 clang-1001.0.46.3)."

[JonasVautherin]

But then I don't really get how I was getting the error mentioned above 🤔... And that's unfortunate, because it would actually be practical to use swiftenv with Carthage, right? 😅.

[davisford]

Who / what sets the SWIFT_VERSION environment variable?

[kylef]

I am not completely sure, but it seems to me that Xcode sets SWIFT_VERSION in a way that is incompatible with swiftenv.

The Xcode build configuration SWFIT_VERSION is different to the environmental variable SWIFT_VERSION and I think this is unrelated.

But then I don't really get how I was getting the error mentioned above 🤔... And that's unfortunate, because it would actually be practical to use swiftenv with Carthage, right? 😅.

If I understand correctly, Carthage is an Xcode tool which uses the Xcode build system. swiftenv manages the swift version for the swift CLI which is outside Xcode. Perhaps depending on how the system is configured swiftenv shims could be set to be used in Xcode, not sure if this is possible. Been a while since I last used Xcode but I don't think it picks up on shell configuration (at least for me with fish).

Who / what sets the SWIFT_VERSION environment variable?

The end user usually. Setting the SWIFT_VERSION environmental variable allows users to set the version of swift tools that the swiftenv shims use. swiftenv allows you to use a .swift-version file too, this should be explained in https://swiftenv.fuller.li/en/latest/getting-started.html#switching-swift-versions, the SWIFT_VERSION environemntal variable can be used to tempoarily override those selected versions,

[JonasVautherin]

Not sure where that is going, and I stopped using swiftenv because it doesn't seem to apply to Carthage (anymore?). Thanks for the help!