Unable to build Xcode projects using SwiftPM in MacPorts sandbox

[Zero King]

Hi Ryan,

On Sat, Mar 23, 2024 at 11:19:03PM -0500, Ryan Schmidt wrote:
>On Mar 23, 2024, at 23:00, Zero King wrote:
>>
>> I think it could be base's sandbox that prevented writes to the home directory, where SwiftPM stores its cache.
>
>If disabling sandboxing in macports.conf makes it work, then your suspicion is probably correct.

Yes, it was the sandbox. I set `sandbox_enable no` and this error was 
gone.

>MacPorts sets the HOME environment variable to point to a directory within workpath. It looks like it's ignoring that and trying to write to a subdirectory of the macports user's real home directory, /opt/local/var/macports/home. That would be a bug to file with Apple. It has been a long-standing problem that has affected MacPorts in other ways before.

SwiftPM seems to prefer the "idiomatic" cache directory, which is 
constructed from FileManager's .cachesDirectory that points to 
Library/Caches.

https://github.com/apple/swift-tools-support-core/blob/930e82e5ae2432c71fe05f440b5d778285270bdb/Sources/TSCBasic/FileSystem.swift#L462
https://github.com/apple/swift-package-manager/blob/9d48dc70aab03a1824ee63abdf105212e08b1dbd/Sources/Basics/FileSystem/FileSystem%2BExtensions.swift#L241-L265
https://developer.apple.com/documentation/foundation/filemanager/searchpathdirectory/cachesdirectory

I'm not sure whether to file this as a bug. At its root is the 
FileManager, but I doubt Apple would change its API.

SwiftPM has a cache-path option that could be used to override the cache 
path, but I'm not sure how to use it in an Xcode project yet.

-- 
Zero