Conditional target dependencies proposal implementation

[hartbit]

This is the implementation of the target dependency proposal that I plan to write a proposal for. I implemented it so that it only affects the build plan, but not the dependency resolver. This allows the Package.resolved file to stay platform and configuration independent:

• I modified TargetDescription.Dependency, Target.Dependency, ResolvedTarget.Dependency to store the conditions configured in the manifest for each case.
• I merged Target.dependencies and Target.targetDeps into one Target.dependencies property containing all dependencies, and adapted code using those properties in consequence.
• I modified ResolvedTarget.recursiveDependencies to get all dependencies (target + product) and added a recursiveTargetDependencies function to do what the previous function did. I also added a buildDependencies function to filter dependencies that satisfy an certain build environment. Similarly, I defined recursiveBuildDependencies and recursiveBuildTargetDependencies that do the same thing but recursively.
• I created reachableBuildTargets and reachableBuildProducts functions on PackageGraph that mirror the reachableTargets and reachableProducts properties but filter dependencies that don't satisfy the input environment.
• Using the above new properties and functions, I modified the implementation of LLBuildManifestBuilder and BuildPlan to only take into account dependencies that satisfy the build environment.

But I'm facing one issue: how to generate an Xcode project with targets that have conditional dependencies on configuration? I don't want to add target dependencies universally. I'm not even sure if this is supported by Xcode. Any ideas?

[hartbit]

@swift-ci please smoke test

[hartbit]

@swift-ci please smoke test

[jakepetroules]

But I'm facing one issue: how to generate an Xcode project with targets that have conditional dependencies on configuration? I don't want to add target dependencies universally. I'm not even sure if this is supported by Xcode. Any ideas?

For linkage you can use EXCLUDED_SOURCE_FILE_NAMES tricks, but for target dependencies, there's no way to conditionalize them.

[hartbit]

@jakepetroules Thanks for the answer! As it won't be able to officially support conditional target dependencies, @aciidb0mb3r suggested outputting a warning in those situations, which I have done. The implementation is now complete from my side.

[aciidgh]

Is it not possible to let compiler auto synthesize this?

[hartbit]

No, because we don't want to have equality on conditions.

[aciidgh]

I have minor nitpicky comments but it looks great! Thanks for working on it!

[hartbit]

@swift-ci please smoke test

[rvenable]

@jakepetroules Thanks for the answer! As it won't be able to officially support conditional target dependencies, @aciidb0mb3r suggested outputting a warning in those situations, which I have done. The implementation is now complete from my side.

So it sounds like .when(configuration: .debug) won't work at all for generating Xcode projects. Is that true? What about when just opening the Package.swift in Xcode without generating a project? Will Xcode be able to handle this? If so, will Xcode actually put flags into the build so that #if DEBUG conditions can be used in source code?

[E13Lau]

@jakepetroules Thanks for the answer! As it won't be able to officially support conditional target dependencies, @aciidb0mb3r suggested outputting a warning in those situations, which I have done. The implementation is now complete from my side.

So it sounds like .when(configuration: .debug) won't work at all for generating Xcode projects. Is that true? What about when just opening the Package.swift in Xcode without generating a project? Will Xcode be able to handle this? If so, will Xcode actually put flags into the build so that #if DEBUG conditions can be used in source code?

Same question.How can i using .when(configuration: .debug) with iOS project? That's no way to edit the Package.swift.