[GHC] #15738: -ddump-splices omits required parentheses around quantified constraints

[GHC]

#15738: -ddump-splices omits required parentheses around quantified constraints
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Template Haskell  |              Version:  8.6.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D5222
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"02b2116e458357e87718e7378a80579a7021e2a7/ghc" 02b2116/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="02b2116e458357e87718e7378a80579a7021e2a7"
 Fix #15738 by defining (and using) parenthesizeHsContext

 With `QuantifiedConstraints`, `forall`s can appear in more
 nested positions than they could before, but `Convert` and the TH
 pretty-printer were failing to take this into account. On the
 `Convert` side, this is fixed by using a `parenthesizeHsContext`
 to parenthesize singleton quantified constraints that appear to the
 left of a `=>`. (A similar fix is applied to the TH pretty-printer.)

 Test Plan: make test TEST=T15738

 Reviewers: goldfire, bgamari

 Reviewed By: bgamari

 Subscribers: rwbarton, carter

 GHC Trac Issues: #15738

 Differential Revision: https://phabricator.haskell.org/D5222
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15738#comment:2>
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