Introduction

This is a proposal to separate out (some) target's runtime into separate repos for better project integration.

For e.g.: The current way of importing the Swift Antlr4 runtime is not ideal because:

1. It can only work with Xcode. (all of the configuration is Xcode dependent) so it does not work on non-darwin platforms.
2. It does not work with Swift Package Manager (1st party support for Swift's dependency management), neither Carthage (3rd party package manager) which also requires a git repo or at least a remote space that stores the artifact (not ideal for Swift because of ABI stability).

Motivation

Although in 4.6 release we added SPM integration, but without a separate repo for swift target, the workflow is like this:

• clone/fork the antlr4 repository
• 'git init' in the swift runtime folder, and tag the runtime repository
• create a remote repository that should hold the swift runtime
• push to the remote repository just created
• add the remote repository as dependency in our projects SPM manifest file.
• run 'swift build' will then pull dependency from the repository

This workflow is awkward. Reference.

This change will end all the hassle in adding swift runtime to a project, and instead, make it as easy as adding the git repository to Package.swift:

let package = Package(
  name: "ProjectUsingSwiftRuntime",
  targets: [
    Target(name: "ProjectUsingSwiftRuntime", dependencies: []),
  ],
  dependencies: [
    .Package(url: "https://github.com/antlr/antlr4-swift-runtime.git", majorVersion: x.x.x)
  ]
)