Support constructor Haddocks in more places

This adds support for adding Haddocks on individual non-record fields
of regular (and GADT) constructors. The following now parses just fine
with `-haddock` enabled:

data Foo
  = Baz             -- ^ doc on the `Baz` constructor
      Int           -- ^ doc on the `Int` field of `Baz`
      String        -- ^ doc on the `String` field of `Baz`

  | Int             -- ^ doc on the `Int` field of the `:*` constructor
      :*            -- ^ doc on the `:*` constructor
    String          -- ^ doc on the `String` field of the `:*`
constructor

  | Boa             -- ^ doc on the `Boa` record constructor
      { y :: () }

The change is backwards compatible: if there is only one doc and it
occurs
on the last field, it is lifted to apply to the whole constructor (as
before).

Reviewers: bgamari, alanz

Subscribers: rwbarton, thomie, mpickering, carter

Differential Revision: https://phabricator.haskell.org/D4292

0 files changed, 0 insertions, 0 deletions