[commit: ghc] ghc-7.8: Honour the untouchability of kind variables (eefd614)

[git at git.haskell.org]

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

On branch  : ghc-7.8
Link       : http://ghc.haskell.org/trac/ghc/changeset/eefd614ae7ebe49bcf3df0d7ab1144a40e647bdf/ghc

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commit eefd614ae7ebe49bcf3df0d7ab1144a40e647bdf
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Mon Apr 14 13:03:40 2014 +0100

    Honour the untouchability of kind variables
    
    Trac #8985 showed up a major shortcoming in the kind unifier: it was
    ignoring untoucability.  This has unpredictably-bad consequences;
    notably, the skolem-escape check can fail.
    
    There were two things wrong
     * TcRnMonad.isTouchableTcM was returning a constant value for kind variables
       (wrong), and even worse the constant was back-to-front (it was always False).
    
     * We weren't even calling isTouchableTcM in TcType.unifyKindX.
    
    I'm not sure how this ever worked.
    
    Merge to 7.8.3 in due course.
    
    (cherry picked from commit e7f0ae7ff4f2199abe42f20bac825a7802bff466)


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eefd614ae7ebe49bcf3df0d7ab1144a40e647bdf
 compiler/typecheck/TcRnMonad.lhs |    5 --
 compiler/typecheck/TcUnify.lhs   |  138 +++++++++++++++++++++++---------------
 2 files changed, 84 insertions(+), 59 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 eefd614ae7ebe49bcf3df0d7ab1144a40e647bdf