[GHC] #13834: Error cascade with type applications

[GHC]

#13834: Error cascade with type applications
-------------------------------------+-------------------------------------
        Reporter:  mpickering        |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
                                     |  TypeApplications, TypeErrorMessages
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #12794            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 As dbaynard noted in
 https://ghc.haskell.org/trac/ghc/ticket/12092#comment:4, things are even
 worse on GHC 8.6 than they used to be. That is, while you'd get these
 errors on GHC 8.4.4:

 {{{
 $ /opt/ghc/8.4.4/bin/ghc -XTypeApplications -e "notInScope @Bool"

 <interactive>:0:1: error: Variable not in scope: notInScope

 <interactive>:0:1: error:
     • Cannot apply expression of type ‘t1’
       to a visible type argument ‘Bool’
     • In the expression: notInScope @Bool
       In an equation for ‘it’: it = notInScope @Bool
 }}}

 You don't even get the `Variable not in scope` error on GHC 8.6.3:

 {{{
 $ /opt/ghc/8.6.3/bin/ghc -XTypeApplications -e "notInScope @Bool"

 <interactive>:0:1: error:
     • Cannot apply expression of type ‘t1’
       to a visible type argument ‘Bool’
     • In the expression: notInScope @Bool
       In an equation for ‘it’: it = notInScope @Bool
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13834#comment:5>
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