Building via Carthage may result in misleading output

[fredpi]

Configuration

The Package.swift of a project includes dependency A. A itself has its Package.swift declared, requiring subdependency B. A is also Carthage-compatible, meaning it has a Cartfile referencing B.

Issue

Accio is smart, so it will build B before building A. Now, if A is built via Carthage, Accio will also copy the build result of B into the Carthage/Build/ folder within the A checkout. After that, the carthage build command is invoked, passing the platform to build for. Carthage will now parse the Cartfile of A if it exists (if A is Carthage-compatible, it will exist).

If the parsing goes well, Carthage will build A using the build result of B that was copied into the Carthage/Build/ folder within the A checkout. Yet, if the parsing doesn't go well, e. g. because B doesn't have a specific shared iOS scheme while the platform passed to the Carthage build command is iOS, there will be an output originating from Carthage similar to this one:

✨  Building library RxGesture with Carthage ...
*** xcodebuild output can be found in /var/folders/r6/ylx9g2f91bxcy402jv2w_3fh0000gn/T/carthage-xcodebuild.QYGDy2.log
*** Skipped building RxSwift due to the error:
Dependency "RxSwift" has no shared framework schemes for any of the platforms: iOS

If you believe this to be an error, please file an issue with the maintainers at https://github.com/ReactiveX/RxSwift/issues/new
*** Building scheme "RxGesture-iOS" in RxGesture.xcodeproj
✨  Completed building scheme RxGesture with Carthage.

However, because RxSwift has already been built via Accio before and copied to Carthage/Build/ folder within the A checkout, this doesn't have any effect, but may irritate the user.

Solution

We can simply fix this misleading output by removing the Cartfile and Cartfile.resolved just before invoking the carthage build command:

// remove Cartfile before carthage build as subdependencies have already been built via Accio
try bash("rm -rf '\(framework.projectDirectory)/Cartfile'")
try bash("rm -rf '\(framework.projectDirectory)/Cartfile.resolved'")

This way, Carthage will just build and do nothing else.