SPM - Target Dependency Condition ignored for .target dependencies

[gpfister]

Describe the bug

I have a package which holds my Cloud API (built on Firebase). I have multiple apps (macOS, iOS) which uses this API, shared as a single package. I'm now trying to build a watchOS companion App, and some of the Firebase API is not provided, namely the Analytics. So I split my code into multiple libraries (inside the same package), and user condition: .when(platforms: [.iOS, .macOS]) so that I can only included dependencies (Analytics is a behind the scene piece, not really something I manipulate within the app).

However, the condition is ignored, it tries to build this target which fails because the framework is missing for watchOS.

To Reproduce

Here's a swift package example:

import PackageDescription

let package = Package(
    name: "OSKCloudKit",
    platforms: [.iOS(.v15), .macOS(.v12), .watchOS(.v8)],
    products: [
        .library(
            name: "OSKCloudAnalytics",
            targets: ["OSKCloudAnalytics"]
        ),
        .library(
            name: "OSKCloudAuth",
            targets: ["OSKCloudAuth"]
        ),
        .library(
            name: "OSKCloudCore",
            targets: ["OSKCloudCore"]
        ),
        .library(
            name: "OSKCloudModel",
            targets: ["OSKCloudModel"]
        ),
        .library(
            name: "OSKCloudServices",
            targets: ["OSKCloudServices"]
        )
    ],
    dependencies: [
        .package(url: "https://github.com/firebase/firebase-ios-sdk.git", .upToNextMajor(from: "9.2.0")),
    ],
    targets: [
        .target(
            name: "OSKCloudAnalytics",
            dependencies: [
                .product(name: "FirebaseAnalytics", package: "firebase-ios-sdk"),
                .product(name: "FirebaseCrashlytics", package: "firebase-ios-sdk"),
            ]
        ),
        .target(
            name: "OSKCloudAuth",
            dependencies: [
                .target(name: "OSKCloudAnalytics", condition: .when(platforms: [.iOS, .macOS])),
                .target(name: "OSKCloudModel"),
                .product(name: "FirebaseAuth", package: "firebase-ios-sdk"),
            ]
        ),
        .target(
            name: "OSKCloudCore",
            dependencies: [
                .product(name: "FirebaseAppCheck", package: "firebase-ios-sdk", condition: .when(platforms: [.iOS, .macOS])),
                .product(name: "FirebaseAuth", package: "firebase-ios-sdk"),
                .product(name: "FirebaseFirestore", package: "firebase-ios-sdk", condition: .when(platforms: [.iOS, .macOS])),
                .product(name: "FirebaseFunctions", package: "firebase-ios-sdk"),
                .product(name: "FirebaseStorage", package: "firebase-ios-sdk")
            ]
        ),
        .target(
            name: "OSKCloudModel",
            dependencies: [
                .product(name: "FirebaseFirestoreSwift", package: "firebase-ios-sdk", condition: .when(platforms: [.iOS, .macOS])),
            ]
        ),
        .target(
            name: "OSKCloudServices",
            dependencies: [
                .target(name: "OSKCloudAnalytics"),
                .target(name: "OSKCloudModel"),
                .product(name: "FirebaseAnalytics", package: "firebase-ios-sdk"),
                .product(name: "FirebaseFirestore", package: "firebase-ios-sdk"),
                .product(name: "FirebaseFunctions", package: "firebase-ios-sdk"),
                .product(name: "FirebaseStorage", package: "firebase-ios-sdk")
            ]
        ),
        .testTarget(
            name: "OSKCloudKitTests",
            dependencies: [
                "OSKCloudModel",
                "OSKCloudServices",
            ]
        ),
    ]
)

When building OSKCloudAuth on iOS device, it works, on watchOS device it fails:

/Users/xxxxxxxx/Library/Developer/Xcode/DerivedData/ios-oskey-dev-azwwbbesmdjzuvbwptqniydxopne/SourcePackages/artifacts/firebase-ios-sdk/FirebaseAnalytics.xcframework:1:1: While building for watchOS Simulator, no library for this platform was found in '/Users/gpfister/Library/Developer/Xcode/DerivedData/ios-oskey-dev-azwwbbesmdjzuvbwptqniydxopne/SourcePackages/artifacts/firebase-ios-sdk/FirebaseAnalytics.xcframework'.

Expected behavior

The target OSKCloudAuth has a dependency on OSKCloudAnalytics:

        .target(
            name: "OSKCloudAuth",
            dependencies: [
                .target(name: "OSKCloudAnalytics", condition: .when(platforms: [.iOS, .macOS])),
                .target(name: "OSKCloudModel"),
                .product(name: "FirebaseAuth", package: "firebase-ios-sdk"),
            ]
        ),

It should not try to build it, just like if it was:

        .target(
            name: "OSKCloudAuth",
            dependencies: [
                .target(name: "OSKCloudModel"),
                .product(name: "FirebaseAuth", package: "firebase-ios-sdk"),
            ]
        ),

Screenshots
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Environment (please complete the following information):

• OS: macOS 12.4
• Xcode Version/Tag/Branch: Xcode 13.4.1

Additional context
Add any other context about the problem here.

[pchelnikov]

@gpfister did you find any solution? I've got the same issue when I updated Facebook SDK.

[gpfister]

@pchelnikov No, I think the issue is in the way SPM works: it should not try to resolve the dependency (i.e. check for a valid product with that name in the package for the arch you are building for), but check the conditions first, and only resolve it if they are met.

As a workaround, I proposed to Firebase team to allow the target to be built on any arch (even if the build fails, as it will not try to build it). That way SPM finds the product for the arch, but ignores it because it doesn't meet the condition.

Should I be in the shoes of thoses providing the SDK, I would argue that this is something that should be fixed here, as workaround is not a sustainable approach.

[gohnjanotis]

Has anyone found a workaround for this? I'd really like to be able to use Xcode Previews for watchOS apps.

[gpfister]

@gohnjanotis: This doesn't seem to get any attention from the project team...

[AnthonyLatsis]

This looks like a package manager issue, not a compiler one. @hborla Should we transfer it?

[neonichu]

The issue here is that we have two competing definitions of what should be built for root packages. On the one hand, there's the rule to always build all targets, on the other hand there's the reasonable expectation that if a target is conditionalized at least once, it should not be build in that context.

We're aware of this issue and it has recently been fixed for SwiftPM itself #5784 -- an equivalent fix will be needed on the Xcode build system side to solve this concrete case, though (tracked by rdar://91946186).

[gpfister]

Thank you for the feedback. It seems that this issue can be closed.

[linkrjr]

Do we have a solution for this in xcode?

[NikolayJuly]

I have same issue. Work with "swift build" in terminal and doesn't work in xcode. Here id Feedback id - FB15945161