[GHC] #12688: derived Show instances aren't protected from RebindableSyntax+OverloadedStrings

[GHC]

#12688: derived Show instances aren't protected from
RebindableSyntax+OverloadedStrings
-------------------------------------+-------------------------------------
        Reporter:  daviddarais       |                Owner:  RyanGlScott
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.0.2
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
                                     |  rebindablesyntax overloadedstrings
                                     |  deriving show string
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2591
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Ryan Scott <ryan.gl.scott@…>):

 In [changeset:"b501709ed79ba03e72518ef9dd101ce2d03db2de/ghc" b501709/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="b501709ed79ba03e72518ef9dd101ce2d03db2de"
 Fix Show derivation in the presence of RebindableSyntax/OverloadedStrings

 Summary:
 To fix this issue, we simply disable `RebindableSyntax` whenever we rename
 the code generated from a deriving clause.

 Fixes #12688.

 Test Plan: make test TEST=T12688

 Reviewers: simonpj, austin, bgamari

 Reviewed By: simonpj, bgamari

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D2591

 GHC Trac Issues: #12688
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12688#comment:5>
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