[GHC] #16401: Bad error message if we use TypeApplications with an identifier that doesn't exist

[GHC]

#16401: Bad error message if we use TypeApplications with an identifier that
doesn't exist
-------------------------------------+-------------------------------------
        Reporter:  Fuuzetsu          |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.3
      Resolution:  duplicate         |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13834            |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by RyanGlScott):

 * status:  new => closed
 * resolution:   => duplicate
 * related:   => #13834


Comment:

 Thanks for the bug report. This is "fixed" in GHC 8.8 in the sense that it
 will at least report that `doesNotExist` is not in scope:

 {{{
 [1 of 1] Compiling BadError         ( Bug.hs, interpreted )

 Bug.hs:6:7: error: Variable not in scope: doesNotExist
   |
 6 | foo = doesNotExist @123
   |       ^^^^^^^^^^^^

 Bug.hs:6:7: error:
     • Cannot apply expression of type ‘t1’
       to a visible type argument ‘123’
     • In the expression: doesNotExist @123
       In an equation for ‘foo’: foo = doesNotExist @123
   |
 6 | foo = doesNotExist @123
   |       ^^^^^^^^^^^^^^^^^
 }}}

 Of course, there's still the confusing "Cannot apply expression" part.
 That has previously been reported as #13834, so to avoid ticket
 duplication, I'll close this ticket in favor of that one.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16401#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler