[commit: ghc] ghc-8.4: Refactor coercion holes (b586f77)

[git at git.haskell.org]

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

On branch  : ghc-8.4
Link       : http://ghc.haskell.org/trac/ghc/changeset/b586f77b3384ce4d38e83205e7c0355c9b626b0a/ghc

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

commit b586f77b3384ce4d38e83205e7c0355c9b626b0a
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Thu Dec 21 13:31:13 2017 +0000

    Refactor coercion holes
    
    In fixing Trac #14584 I found that it would be /much/ more
    convenient if a "hole" in a coercion (much like a unification
    variable in a type) acutally had a CoVar associated with it
    rather than just a Unique.  Then I can ask what the free variables
    of a coercion is, and get a set of CoVars including those
    as-yet-un-filled in holes.
    
    Once that is done, it makes no sense to stuff coercion holes
    inside UnivCo.  They were there before so we could know the
    kind and role of a "hole" coercion, but once there is a CoVar
    we can get that info from the CoVar.  So I removed HoleProv
    from UnivCoProvenance and added HoleCo to Coercion.
    
    In summary:
    
    * Add HoleCo to Coercion and remove HoleProv from UnivCoProvanance
    
    * Similarly in IfaceCoercion
    
    * Make CoercionHole have a CoVar in it, not a Unique
    
    * Make tyCoVarsOfCo return the free coercion-hole variables
      as well as the ordinary free CoVars.  Similarly, remember
      to zonk the CoVar in a CoercionHole
    
    We could go further, and remove CoercionHole as a distinct type
    altogther, just collapsing it into HoleCo.  But I have not done
    that yet.
    
    (cherry picked from commit a492af06d3264530d134584f22ffb726a16c78ec)


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

b586f77b3384ce4d38e83205e7c0355c9b626b0a
 compiler/backpack/RnModIface.hs          |  1 +
 compiler/coreSyn/CoreFVs.hs              |  2 +-
 compiler/coreSyn/CoreLint.hs             |  7 ++-
 compiler/iface/IfaceSyn.hs               |  5 +-
 compiler/iface/IfaceType.hs              | 56 ++++++++++-----------
 compiler/iface/TcIface.hs                |  5 +-
 compiler/iface/ToIface.hs                |  5 +-
 compiler/typecheck/TcCanonical.hs        |  2 +-
 compiler/typecheck/TcEnv.hs              | 16 ++++--
 compiler/typecheck/TcErrors.hs           |  6 +--
 compiler/typecheck/TcHsSyn.hs            | 30 +++++-------
 compiler/typecheck/TcInteract.hs         |  6 +--
 compiler/typecheck/TcMType.hs            | 75 +++++++++++++++-------------
 compiler/typecheck/TcPluginM.hs          |  4 +-
 compiler/typecheck/TcRnTypes.hs          | 25 ++++++----
 compiler/typecheck/TcSMonad.hs           |  4 +-
 compiler/typecheck/TcTyDecls.hs          |  2 +-
 compiler/typecheck/TcType.hs             | 14 +++---
 compiler/typecheck/TcUnify.hs            | 19 +++++---
 compiler/typecheck/TcValidity.hs         |  4 +-
 compiler/types/Coercion.hs               | 42 +++++++---------
 compiler/types/FamInstEnv.hs             |  2 +-
 compiler/types/OptCoercion.hs            |  7 +--
 compiler/types/TyCoRep.hs                | 84 +++++++++++++++++++-------------
 compiler/types/Type.hs                   | 19 ++++----
 testsuite/tests/polykinds/T11821a.stderr |  2 +-
 testsuite/tests/polykinds/T14563.stderr  |  4 +-
 27 files changed, 237 insertions(+), 211 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 b586f77b3384ce4d38e83205e7c0355c9b626b0a