[commit: ghc] ghc-8.2: Fix the pure unifier (aa39137)

[git at git.haskell.org]

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

On branch  : ghc-8.2
Link       : http://ghc.haskell.org/trac/ghc/changeset/aa39137316fcbb555bcb676cb2f89002d97d3e3c/ghc

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

commit aa39137316fcbb555bcb676cb2f89002d97d3e3c
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Tue May 16 15:43:55 2017 +0100

    Fix the pure unifier
    
    This patch fixes Trac #13705, by fixing a long-standing outright bug
    in the pure unifier.  I'm surprised this hasn't caused more trouble
    before now!
    
    (cherry picked from commit cec7d580c2c033c3aaeba093752328d8f3635cd0)


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

aa39137316fcbb555bcb676cb2f89002d97d3e3c
 compiler/types/Unify.hs                            | 380 ++++++++++-----------
 .../tests/indexed-types/should_compile/T13705.hs   |  15 +
 testsuite/tests/indexed-types/should_compile/all.T |   1 +
 3 files changed, 200 insertions(+), 196 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 aa39137316fcbb555bcb676cb2f89002d97d3e3c