[GHC] #8978: Type synonyms in class associated types behave strangely

[GHC]

#8978: Type synonyms in class associated types behave strangely
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        Reporter:  joelteon                   |            Owner:
            Type:  bug                        |           Status:  closed
        Priority:  highest                    |        Milestone:  7.8.2
       Component:  Compiler                   |          Version:  7.8.1
      Resolution:  fixed                      |         Keywords:
Operating System:  Unknown/Multiple           |     Architecture:
 Type of failure:  GHC rejects valid program  |  Unknown/Multiple
       Test Case:                             |       Difficulty:  Unknown
        Blocking:                             |       Blocked By:
                                              |  Related Tickets:
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Comment (by Lemming):

 Replying to [comment:12 simonpj]:

 > Who else has come across this?

 I encountered the bug when working on the tfp package. I could fix one
 problem within the package using the one-equation type family work-around.
 But the bug also affected the dependending llvm-tf package at several
 places. Thus I stopped working around and this means, that there might be
 more yet unseen places where it causes problems.
 Before a new release I would like very much to get a "nightly snapshot
 build" or "release candidate" for testing on 64-bit Linux. Otherwise I am
 afraid that the bugfix causes other subtle problems that will be part of
 7.8.2.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8978#comment:16>
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