[GHC] #10547: feature request: expanding type synonyms in error messages

[GHC]

#10547: feature request: expanding type synonyms in error messages
-------------------------------------+-------------------------------------
        Reporter:  osa1              |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  low               |            Milestone:  8.0.1
       Component:  Compiler (Type    |              Version:
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
                                     |  typecheck/should_fail/ExpandSynsFail1,2,3,4
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1016
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by ezyang):

 * status:  closed => new
 * owner:  osa1 =>
 * resolution:  fixed =>


Comment:

 I think we should improve this a bit more. For one, this is not on by
 default, right? Any reason it shouldn't be? And if it's not on by default,
 GHC should at least mention that you can pass `-fprint-expanded-synonyms`
 to see the expansion of the type synonyms.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10547#comment:12>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler