glibc warnings compiling for 5.9-RELEASE_ubuntu_jammy_aarch64

[rvsrvs]

I've created a simple helloworld tool, and compiling it generates warning messages that seem to be spurious. Here's the project structure:

./Package.swift
./Sources/helloworld/main.swift
./Tests/LinuxMain.swift
./Tests/helloworldTests/helloworldTests.swift
./Tests/helloworldTests/XCTestManifests.swift

Package consists of:

// swift-tools-version:5.9
import PackageDescription

let package = Package(
    name: "helloworld",
    dependencies: [],
    targets: [
        .executableTarget(
            name: "helloworld",
            dependencies: []
        ),
        .testTarget(
            name: "helloworldTests",
            dependencies: ["helloworld"]
        ),
    ]
)

main.swift consists of:

print("Successful launch!")

This produces the following output:

swift build --experimental-swift-sdk 5.9-RELEASE_ubuntu_jammy_aarch64
Building for debugging...
warning: Could not read SDKSettings.json for SDK at: /Users/rvs/Library/org.swift.swiftpm/swift-sdks/5.9-RELEASE_ubuntu_jammy_aarch64.artifactbundle/5.9-RELEASE_ubuntu_jammy_aarch64/aarch64-unknown-linux-gnu/ubuntu-jammy.sdk
<unknown>:0: warning: glibc not found for 'aarch64-unknown-linux-gnu'; C stdlib may be unavailable
<unknown>:0: warning: glibc not found for 'aarch64-unknown-linux-gnu'; C stdlib may be unavailable
warning: Could not read SDKSettings.json for SDK at: /Users/rvs/Library/org.swift.swiftpm/swift-sdks/5.9-RELEASE_ubuntu_jammy_aarch64.artifactbundle/5.9-RELEASE_ubuntu_jammy_aarch64/aarch64-unknown-linux-gnu/ubuntu-jammy.sdk
[5/5] Linking helloworld
Build complete! (9.02s)

The glibc warnings seem to be spurious.