[GHC] #12794: Out of scope error not reported

[GHC]

#12794: Out of scope error not reported
-------------------------------------+-------------------------------------
           Reporter:  simonpj        |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           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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 Consider
 {{{
 {-# LANGUAGE TypeApplications #-}
 {-# OPTIONS -fdefer-type-errors #-}

 f = bar @Int
 }}}
 where `bar` is not in scope.  We get
 {{{
 T12768.hs:8:7: error:
     • Cannot apply expression of type ‘t1’
       to a visible type argument ‘Int’
     • In the expression: bar @Int
 }}}
 Confusingly, the "`bar` is not in scope`" error (the true error) has been
 suppressed.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12794>
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