[commit: ghc] master: Fix DeriveAnyClass (again) (fd841f8)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/fd841f877ab7a991f667a50b401404927f6f599c/ghc

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

commit fd841f877ab7a991f667a50b401404927f6f599c
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Tue Feb 21 10:27:41 2017 +0000

    Fix DeriveAnyClass (again)
    
    This patch fixes Trac #13272.  The general approach was fine, but
    we were simply not generating the correct implication constraint
    (in particular generating fresh unification variables).  I added
    a lot more commentary to Note [Gathering and simplifying
    constraints for DeriveAnyClass]
    
    I'm still not very happy with the overall architecture.  It feels
    more complicate than it should.


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

fd841f877ab7a991f667a50b401404927f6f599c
 compiler/typecheck/TcDerivInfer.hs                 | 244 +++++++++++----------
 testsuite/tests/deriving/should_compile/T13272.hs  |  23 ++
 testsuite/tests/deriving/should_compile/T13272a.hs |  21 ++
 testsuite/tests/deriving/should_compile/all.T      |   2 +
 4 files changed, 172 insertions(+), 118 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 fd841f877ab7a991f667a50b401404927f6f599c