Alan Zimmerman authored Oct 25, 2015 and Ben Gamari committed Oct 25, 2015

It is difficult for GHC developers to know if they have broken the API
Annotations.

This patch provides a utility that can be used as a test to show up
errors in the API Annotations.

It is based on the current tests for ghc-api/annotations which can parse
a file using the just-built GHC API, and check that no annotations are
disconnected from the ParsedSource in the output.

In addition, it should be able to dump the annotations to a file, so a
new feature developer can check that all changes to the parser do
provide annotations.

Trac ticket: #10917

Test Plan: ./validate

Reviewers: hvr, thomie, austin, bgamari

Reviewed By: bgamari

Differential Revision: https://phabricator.haskell.org/D1368

GHC Trac Issues: #10917