Swift Package Manager: dependency iOS version

I'm trying to build swift package with external dependency (CoreStore) with xCode11 beta 7. My package is targeted for iOS11+, it's declared in Package.swift:

// swift-tools-version:5.1
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "Storages",
    platforms: [.iOS(.v11)],
    products: [
        // Products define the executables and libraries produced by a package, and make them visible to other packages.
        .library(
            name: "Storages",
            targets: ["Storages"]),
    ],
    dependencies: [
        // Dependencies declare other packages that this package depends on.
        .package(url: "https://github.com/JohnEstropia/CoreStore.git", from: "6.3.0")
    ],
    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: "Storages",
            dependencies: [.product(name: "CoreStore")]),

        .testTarget(
            name: "StoragesTests",
            dependencies: ["Storages"]),
    ]
)

However, when I build it dependency builds without iOS version specified, so I get compatibility errors: "'uniquenessConstraints' is only available in iOS 9.0 or newer" and so on.

How can I fix it? Looks like it's xCode11 bug, but I'm not sure.

I'm not sure is it xCode bug or not, however with Swift Package Manager and xCode 11 you have to clearly specify iOS version when use #available check. Not matter if library is targeted for iOS 10+ or not, instead of

if #available(macOS 10.11, *) {
    info.append(("uniquenessConstraints", self.uniquenessConstraints))
}

you should use

if #available(macOS 10.11, iOS 9.0, *) {
    info.append(("uniquenessConstraints", self.uniquenessConstraints))
}

Pull request was posted: https://github.com/JohnEstropia/CoreStore/pull/341