[commit: ghc] master: Refactor TcDeriv and TcGenDeriv (4a03012)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/4a03012aeb4cb6685221b30aea2b1a78145d902b/ghc

>---------------------------------------------------------------

commit 4a03012aeb4cb6685221b30aea2b1a78145d902b
Author: Ryan Scott <ryan.gl.scott at gmail.com>
Date:   Thu Oct 6 09:14:49 2016 -0400

    Refactor TcDeriv and TcGenDeriv
    
    Summary:
    Keeping a promise I made to Simon to clean up these modules.
    
    This change splits up the massive `TcDeriv` and `TcGenDeriv` modules into
    somewhat more manageable pieces. The new modules are:
    
    * `TcGenFunctor`: This contains the deriving machinery for `Functor`,
      `Foldable`, and `Traversable` (which all use the same underlying algorithm).
    * `TcDerivInfer`: This is the new home for `inferConstraints`,
      `simplifyInstanceContexts`, and related functions, whose role is to come up
      with the derived instance context and subsequently simplify it.
    * `TcDerivUtils`: This is a grab-bag module that contains several
      error-checking utilities originally in `TcDeriv`, as well as some functions
      that `TcDeriv` and `TcDerivInfer` both need.
    
    The end result is that `TcDeriv` is now less than 1,600 SLOC (originally 2,686
    SLOC), and `TcGenDeriv` is now about 2,000 SLOC (originally 2,964).
    
    In addition, this also implements a couple of tiny refactorings:
    
    * I transformed `type Condition = (DynFlags, TyCon) -> Validity` into
      `type Condition = DynFlags -> TyCon -> Validity`
    * I killed the `DerivSpecGeneric` constructor for `DerivSpecMechanism`, and
      merged its functionality into `DerivSpecStock`. In addition,
      `hasStockDeriving` now contains key-value pairs for `Generic` and `Generic1`,
      so they're no longer treated as an awkward special case in `TcDeriv`.
    
    Test Plan: ./validate
    
    Reviewers: simonpj, austin, bgamari
    
    Reviewed By: simonpj
    
    Subscribers: thomie, mpickering
    
    Differential Revision: https://phabricator.haskell.org/D2568


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4a03012aeb4cb6685221b30aea2b1a78145d902b
 compiler/ghc.cabal.in               |    3 +
 compiler/typecheck/TcDeriv.hs       | 1168 +----------------------------------
 compiler/typecheck/TcDerivInfer.hs  |  653 ++++++++++++++++++++
 compiler/typecheck/TcDerivUtils.hs  |  610 ++++++++++++++++++
 compiler/typecheck/TcGenDeriv.hs    |  923 +--------------------------
 compiler/typecheck/TcGenFunctor.hs  |  875 ++++++++++++++++++++++++++
 compiler/typecheck/TcGenGenerics.hs |    1 +
 7 files changed, 2184 insertions(+), 2049 deletions(-)

Diff suppressed because of size. To see it, use:

    git diff-tree --root --patch-with-stat --no-color --find-copies-harder --ignore-space-at-eol --cc 4a03012aeb4cb6685221b30aea2b1a78145d902b