[GHC] #9190: Iface type variable out of scope: s

[GHC]

#9190: Iface type variable out of scope:  s
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        Reporter:  nomeata           |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.9
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"e5257f8fe20f5278c23693f1523e298e6fdaa064/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="e5257f8fe20f5278c23693f1523e298e6fdaa064"
 Fix tyConToIfaceDecl (Trac #9190)

 There are three bugs here, one serious

  * We were failing to tidy the type arguments in an IfTyConParent
    This is what was causing Trac #9190.

  * toIfaceTcArgs is careful to suppress kind arguments, but there
    was a clone, tidyToIfaceTcArgs in IfaceSyn which didn't.
    Now the latter goes via the former.

  * When pretty-printing a IfaceDecl for an algebraic data type, and
    doing so in Haskell-98 syntax, we were silently assuming that the
    universal type variables of the TyCon and the DataCon were the
    same. But that has not been true for some time. Result: a very
    confusing display.

    Solution: during the conversion to IfaceSyn, take the opportunity
    to make the universal type variables line up exactly.  This is very
    easy to do, makes the pretty-printing easy, and leaves open the future
    possiblity of not serialising the universal type variables of the
    data constructor.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9190#comment:10>
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