[GHC] #8569: ASSERT in testcase type-rep, only in some ways:

[GHC]

#8569: ASSERT in testcase type-rep, only in some ways:
-------------------------------------+------------------------------------
        Reporter:  nomeata           |            Owner:
            Type:  bug               |           Status:  closed
        Priority:  normal            |        Milestone:
       Component:  Test Suite        |          Version:  7.7
      Resolution:  wontfix           |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
-------------------------------------+------------------------------------
Changes (by nomeata):

 * status:  new => closed
 * resolution:   => wontfix


Comment:

 Guess I did not update the ticket after later discussions.

 I believe that this is currently a wontfix:

  * The demand analyser is quite untyped, so in the example in comment:3,
 where the two branches of a case happen to have quite different types (one
 being a product, and one not) can only be handled on a best effort basis.
 Therefore, the code needs to cope with situations where a product demand
 does not have the right number of components for the constructor at hand.
 That is also the reason why `lubStr (SCall _)  (SProd _)` should not
 panic.
  * The `Note [Don't optimise UProd(Used) to Used]` continues to be
 relevant: We differentiate these semantically equivalent terms to get some
 insight about how a product is being used.

 I believe the test suite is now set up to reflect this, i.e. type-rep will
 expectedly fail when GHC is compiled with `-DDEBUG` *and* the way is an
 optimizing way.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8569#comment:11>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler