[GHC] #7788: Recursive type family causes <<loop>>

GHC ghc-devs at haskell.org
Tue Dec 30 17:48:21 UTC 2014


#7788: Recursive type family causes <<loop>>
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        Reporter:  shachaf           |                   Owner:  simonpj
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:  7.10.1
       Component:  Compiler (Type    |                 Version:  7.6.2
  checker)                           |                Keywords:
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  Incorrect result  |               Test Case:
  at runtime                         |                Blocking:
      Blocked By:                    |  Differential Revisions:
 Related Tickets:                    |
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Comment (by simonpj):

 Richard, for the evaluation-depth thing, I think that all that is
 necessary is:

  * Call `bumpSubGoalDepth` on the `fe_loc` field of `fmode` in
 `try_to_reduce` in `TcFlatten.flatten_exact_fam_app_fully`.

  * And call `subGoalDepthExceeded` in the same function.

 Or the depth-exceeded check could be in `flatten_one`.

 Might you do this?

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7788#comment:8>
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