Implementation of StrictData language extension

This implements the `StrictData` language extension, which lets the
programmer default to strict data fields in datatype declarations on a
per-module basis.

Specification and motivation can be found at
https://ghc.haskell.org/trac/ghc/wiki/StrictPragma

This includes a tricky parser change due to conflicts regarding `~` in
the type level syntax: all ~'s are parsed as strictness annotations (see
`strict_mark` in Parser.y) and then turned into equality constraints at
the appropriate places using `RdrHsSyn.splitTilde`.

Updates haddock submodule.

Test Plan: Validate through Harbormaster.

Reviewers: goldfire, austin, hvr, simonpj, tibbe, bgamari

Reviewed By: simonpj, tibbe, bgamari

Subscribers: lelf, simonpj, alanz, goldfire, thomie, bgamari, mpickering

Differential Revision: https://phabricator.haskell.org/D1033

GHC Trac Issues: #8347

1 files changed, 0 insertions, 0 deletions

diff --git a/utils/haddock b/utils/haddock
-Subproject 553c719236972f3a1d445146352ec94614979b6
+Subproject 5eb0785cde60997f072c3bdfefaf8c389c96d42