[GHC] #8809: Prettier error messages?

[GHC]

#8809: Prettier error messages?
-------------------------------------+-------------------------------------
        Reporter:  joelteon          |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.9
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
  #8809,#10073,#10179,#12906         |
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Ben Gamari <ben@…>):

 In [changeset:"158530a5450b27eb5ae2d75b7895fd1662dde13b/ghc"
 158530a5/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="158530a5450b27eb5ae2d75b7895fd1662dde13b"
 Add caret diagnostics

 This is controlled by -f[no-]diagnostics-show-caret.

 Example of what it looks like:
 ```
     |
  42 |     x = 1 + ()
     |         ^^^^^^
 ```
 This is appended to each diagnostic message.

 Test Plan:
 testsuite/tests/warnings/should_fail/CaretDiagnostics1
 testsuite/tests/warnings/should_fail/CaretDiagnostics2

 Reviewers: simonpj, austin, bgamari

 Reviewed By: simonpj, bgamari

 Subscribers: joehillen, mpickering, Phyx, simonpj, alanz, thomie

 Differential Revision: https://phabricator.haskell.org/D2718

 GHC Trac Issues: #8809
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8809#comment:44>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler