[GHC] #14771: TypeError reported too eagerly

[GHC]

#14771: TypeError reported too eagerly
-------------------------------------+-------------------------------------
        Reporter:  hsyl20            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |             Keywords:
      Resolution:                    |  CustomTypeErrors
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  error/warning at compile-time      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by diatchki):

 Ok, so I think issue 2) is not related to custom type errors.
 I haven't looked at this part of the error reporting much, but I suspect
 that in some cases GHC forgets that some type expression is the result of
 evaluating a function.  Tricky business.  I'd say it'd be better to file a
 separate ticket for this, especially if you can find a concrete example
 that might point out to exactly what we may fix.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14771#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler