[GHC] #13420: Bizarre pretty-printing of closed type families in GHCi

[GHC]

#13420: Bizarre pretty-printing of closed type families in GHCi
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.4.1
       Component:  GHCi              |              Version:  8.0.2
      Resolution:                    |             Keywords:  TypeFamilies
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3497
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Ben Gamari <ben@…>):

 In [changeset:"da792e47981f65b2dba4fc76ce51dc3fb9c4c02d/ghc"
 da792e47/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="da792e47981f65b2dba4fc76ce51dc3fb9c4c02d"
 Only pretty-print binders in closed type families with -fprint-explicit-
 foralls

 Previously, we were unconditionally pretty-printing all type variable
 binders when pretty-printing closed type families (e.g., in the output
 of `:info` in GHCi). This threw me for a loop, so let's guard this behind
 the `-fprint-explicit-foralls` flag.

 Test Plan: make test TEST=T13420

 Reviewers: goldfire, austin, bgamari

 Reviewed By: bgamari

 Subscribers: rwbarton, thomie

 GHC Trac Issues: #13420

 Differential Revision: https://phabricator.haskell.org/D3497
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13420#comment:4>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler