[commit: ghc] master: This changes fixes a bad error in canonicalisation, concerning kind equality (1128f1e)

[Simon Peyton Jones]

Repository : http://darcs.haskell.org/ghc.git/

On branch  : master

https://github.com/ghc/ghc/commit/1128f1e02ff06fee89b62fb756ac0c28edcf4625

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

commit 1128f1e02ff06fee89b62fb756ac0c28edcf4625
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Wed Apr 3 14:37:50 2013 +0100

    This changes fixes a bad error in canonicalisation, concerning kind equality
    
    We care careful not to construct a canonical equality whose LHS and RHS
    have incompatible kinds.  (This is one of the invariants of a canonical
    equality.)  See Note [Equalities with incompatible kinds].  However,
    what I had not dealt with is when LHS and RHS *look* as if they have
    different kinds, but after zonking they become the same.  Bad!
    
    (This led to an ASSERT failure in the test for Trac #7176.)

 compiler/typecheck/TcCanonical.lhs | 111 ++++++++++++++++++++++---------------
 1 file changed, 65 insertions(+), 46 deletions(-)


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

    git show 1128f1e02ff06fee89b62fb756ac0c28edcf4625