[GHC] #9567: tc124 fails as '*** Core Lint errors : in result of Simplifier ***' in WAY=optasm

[GHC]

#9567: tc124 fails as '*** Core Lint errors : in result of Simplifier ***' in
WAY=optasm
-------------------------------------+-------------------------------------
              Reporter:  slyfox      |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.9
            Resolution:              |         Keywords:
      Operating System:              |     Architecture:  x86_64 (amd64)
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:  GHC         |       Blocked By:
  rejects valid program              |  Related Tickets:
             Test Case:  tc124       |
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------

Comment (by slyfox):

 Slightly more trimmed example
 causing lint crash on the following commandline:
 {{{
 inplace/bin/ghc-stage2 -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-
 output -no-user-package-db -rtsopts -fno-ghci-history -c tc124.hs -O -fasm
 -fno-warn-incomplete-patterns

 *** Core Lint errors : in result of Simplifier ***
 <no location info>: Warning:
     In the type ‘a_12 -> a_anm -> a_anm’
     @ a_12 is out of scope
 *** Offending Program ***

 }}}

 {{{#!hs
 {-# LANGUAGE RankNTypes #-}
 module Foo  where
 data T = T { t1 :: forall a. a -> a }

 -- Test pattern bindings for polymorphic fields
 f :: T -> (Int,Char)
 f t = let T { t1 = my_t1 } = t
       in (my_t1 3, my_t1 'c')
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9567#comment:2>
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