Rule Request: [duplicate_target_in_package]

New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

New rule request

This rule would warn about duplicate targets in a Package.swift file.

Violation:

let package = Package(
    name: "MyPackage",
    platforms: [.iOS(.v14)],
    products: [
        .library(
            name: "MyPackage",
            targets: [
                "BigDependency",
                "SmallDependency",
                "OtherDependency",
                "BigDependency"
            ]),
    ],

Non-violation

let package = Package(
    name: "MyPackage",
    platforms: [.iOS(.v14)],
    products: [
        .library(
            name: "MyPackage",
            targets: [
                "BigDependency",
                "SmallDependency",
                "OtherDependency"
            ]),
    ],

I've seen this problem occur usually when there are two people working on the same swift package. One of them adds a dependency. And the other adds another, and then the branches are merged. It isn't flagged as a problem by the compiler, but can cause issues.

Start by reviewing SwiftLint’s existing rule entry points and test conventions, then use the Package.swift violation and non-violation examples as the behavioral cases. Done means duplicate target names in a Package.swift file produce a warning while unique target names do not.