[GHC] #11098: TH mishandles type variables that begin with an underscore

[GHC]

#11098: TH mishandles type variables that begin with an underscore
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        Reporter:  goldfire          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Template Haskell  |              Version:  7.10.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by jstolarek):

 * cc: jstolarek (added)


Comment:

 I just tried with GHC 7.8.4, 7.10.1 and today's HEAD and I can't reproduce
 this behaviour:

 {{{
 [killy at GLaDOS : /dane/projekty/ghc/ghc-tests]
 /dane/sandboxes/ghc/7.10.1/bin/ghci
 GHCi, version 7.10.1: http://www.haskell.org/ghc/  :? for help
 Prelude> :m + Language.Haskell.TH
 Prelude Language.Haskell.TH> :set -XTemplateHaskell
 Prelude Language.Haskell.TH> :set -XRankNTypes
 Prelude Language.Haskell.TH> runQ [d|foo :: forall _a . _a -> _a ; foo x =
 x|]
 [SigD foo_1 (ForallT [PlainTV _a_0] [] (AppT (AppT ArrowT (VarT _a_0))
 (VarT _a_0))),FunD foo_1 [Clause [VarP x_2] (NormalB (VarE x_2)) []]]
 }}}
 Can you post your whole GHCi session and `~/.ghci`? Or perhaps this bug is
 specific to 7.10.2, but that would be surprising.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11098#comment:1>
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