How to obtain swiftc log for use in swiftlint

Hello,
[SwiftLint](https://github.com/realm/SwiftLint) is an application that can do static analysis of Swift files in order to improve code quality.

The analyze command (which offers some additional capabilities compared to the lint command) requires access to the swiftc log. Currently, I do not think this is exposed except to display error messages when compilation fails.

I was wondering if anyone has integrated this utility into their build, or if there would be interest in accepting a patch to produce the log file as an artifact from the swift_library build rule?

Thank you!

Start by examining the swift_library build rule and how its swiftc compilation information is currently exposed. Compare that with the swiftc log required by SwiftLint's analyze command. Done means the build rule makes the needed log available as an artifact for SwiftLint, with the integration behavior documented or verified.

Written by the indexing model from the issue text.