[Pitch] Adding metadata to SPM Package

[Aciid (Ankit Aggarwal)]

@Ponyboy47

While I do agree that supporting multiple SwiftPM versions is a nightmare

Here's one idea to potentially resolve this problem:

Using #if compiler from now on instead of swift-tools-version annotation

The swift-tools-version annotation is used to determine the version of PackageDescription library that should be used to evaluate the manifest file. We need this information before the manifest can be evaluated. This feature allows SwiftPM to evolve the PackageDescription library without breaking the existing package ecosystem. For e.g., if you update your package's tools version, your clients on older tools version will continue to use the latest version of the older manifest until they update …

It'd be great if someone can write a full proposal for supporting multiple tools versions in a single manifest.