This trait should eventually go away, so we rename it (and supporting types) to make room for a new concrete `Diagnostic` type. This commit is just the rename. In the next commit, we'll move it to a different module.
This trait should eventually go away, so we rename it (and supporting types) to make room for a new concrete `Diagnostic` type. This commit is just the rename. In the next commit, we'll move it to a different module.