[GHC] #15084: Functions in HsUtils don't have the most general type

[GHC]

#15084: Functions in HsUtils don't have the most general type
-------------------------------------+-------------------------------------
           Reporter:  mpickering     |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  high           |         Milestone:  8.6.1
          Component:  Compiler       |           Version:  8.2.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 In 1aa1d405d8212a99ac24dcfd48024a17c3ffd296 the types of a lot of
 functions in
 `HsUtils` was changed and now they are too restrictive. For example,
 `nlHsfunTy` has the following type.

 {{{
 nlHsFunTy :: LHsType (GhcPass p) -> Rig -> LHsType (GhcPass p) -> LHsType
 (GhcPass p)
 }}}


 It should instead be given the more general type which will allow it to
 work as before in many situations.

 {{{
 nlHsFunTy :: (XFunTy p ~ PlaceHolder) => LHsType p -> Rig -> LHsType p ->
 LHsType p
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15084>
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