Swift4でのPackage.swiftエラー #love_swift

Swift愛好会合宿 2018/1/20-1/21で記事書いてます。 #love_swift

Manual Quickstartを参考にVaporでWebサーバー立ててた時の内容です。

$ swift build

をしたときにエラーになりました。

$ swift build
error: manifest parse error(s):
/home/n0bisuke/myswift/webapp/Package.swift:11:10: error: type 'Package.Dependency' has no member 'Package'
        .Package(url: "https://github.com/vapor/vapor.git", majorVersion: 2)
        ~^

$ swift build
error: manifest parse error(s):
/home/n0bisuke/myswift/webapp/Package.swift:10:10: error: ambiguous reference to member 'package'
        .package(url: "https://github.com/vapor/vapor.git", majorVersion: 2),
         ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/n0bisuke/myswift/webapp/Package.swift:10:10: note: overloads for 'package' exist with these partially matching parameter lists: (url: String, from: Version), (url: String, Package.Dependency.Requirement), (url: String, Range<Version>), (url: String, ClosedRange<Version>), (url: String, version: Version), (url: String, branch: String), (url: String, revision: String), (url: String, range: Range<Version>)
        .package(url: "https://github.com/vapor/vapor.git", majorVersion: 2),
         ^

他も見てるとSwift3系までのPackage.Swiftでの例が多いので注意が必要そうです。

3系と4系のPackage.swift

• 3系

// swift-tools-version:3.1

import PackageDescription

let package = Package(
    name: "Hello",
    dependencies: [
        .Package(url: "https://github.com/vapor/vapor.git", majorVersion: 2)
    ]
)

• 4系

// swift-tools-version:4.0
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "webapp",
    dependencies: [
        // Dependencies declare other packages that this package depends on.
        .package(url: "https://github.com/vapor/vapor.git", from: "2.4.0"),
    ],
    targets: [
        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
        // Targets can depend on other targets in this package, and on products in packages which this package depends on.
        .target(
            name: "webapp",
            dependencies: ["Vapor"]),
    ]
)

ざっくりと、.Packageは.packageに、 majorVersionはfromに変更するところです。

Swift Package Manager Manifest API Redesignなど参考にすると良さそうです。