ApiAnnotations : AST version of nested forall loses forall annotation

Summary:
When parsing

    {-# LANGUAGE ScopedTypeVariables #-}

    extremumNewton :: forall tag. forall tag1.
                       tag -> tag1 -> Int
    extremumNewton = undefined

the parser creates nested HsForAllTy's for the two forall statements.

These get flattened into a single one in `HsTypes.mk_forall_ty`

This patch removes the flattening, so that API Annotations are not lost in the
process.

Test Plan: ./validate

Reviewers: goldfire, austin, simonpj

Reviewed By: simonpj

Subscribers: bgamari, mpickering, thomie, goldfire

Differential Revision: https://phabricator.haskell.org/D836

GHC Trac Issues: #10278, #10315, #10354, #10363

0 files changed, 0 insertions, 0 deletions