[commit: ghc] ghc-7.10: Deal with phantom type variables in rules (bdc464f)

[git at git.haskell.org]

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

On branch  : ghc-7.10
Link       : http://ghc.haskell.org/trac/ghc/changeset/bdc464f98d5dbe6fc85cc8dc5e769758ca2796a7/ghc

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

commit bdc464f98d5dbe6fc85cc8dc5e769758ca2796a7
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Wed Jul 29 16:06:29 2015 +0100

    Deal with phantom type variables in rules
    
    See Note [Unbound template type variables] in Rules.hs
    This fixes Trac #10689.
    
    The problem was a rule LHS that mentioned a type variable
    in a phantom argument to a type synonym.  Then matching the
    LHS didn't bind the type variable, and the rule matcher
    complained.
    
    This patch fixes the problem, as described by the Note.
    
    I also went back to not-cloning the template varaibles during
    rule matching.  I'm convinced that it's not necessary now
    (if it ever was), and cloning makes the fix for #10689 much more
    fiddly.


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bdc464f98d5dbe6fc85cc8dc5e769758ca2796a7
 compiler/specialise/Rules.hs                       | 120 +++++++++++++--------
 testsuite/tests/simplCore/should_compile/T10689.hs |  11 ++
 .../tests/simplCore/should_compile/T10689a.hs      | 114 ++++++++++++++++++++
 testsuite/tests/simplCore/should_compile/all.T     |   2 +
 4 files changed, 205 insertions(+), 42 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 bdc464f98d5dbe6fc85cc8dc5e769758ca2796a7