[GHC] #13968: TH gives "Illegal binding of built-in syntax" error

[GHC]

#13968: TH gives "Illegal binding of built-in syntax" error
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Template Haskell  |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Poor/confusing    |  Unknown/Multiple
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3789
       Wiki Page:                    |
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Comment (by Ryan Scott <ryan.gl.scott@…>):

 In [changeset:"d774b4e2de4f07d2432b67010305fede7aeefc78/ghc" d774b4e/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="d774b4e2de4f07d2432b67010305fede7aeefc78"
 Fix #13968 by consulting isBuiltInOcc_maybe

 Summary:
 We were unconditionally reporting `Illegal binding of built-in syntax`
 in an error message, but this error doesn't make sense in certain Template
 Haskell scenarios which can trigger it. Let's give a more sensible error
 message by first checking if the name we're binding really is built-in
 syntax,
 using the handy `isBuiltInOcc_maybe` function.

 Test Plan: make test TEST=T13968

 Reviewers: bgamari, austin, goldfire

 Reviewed By: goldfire

 Subscribers: goldfire, rwbarton, thomie

 GHC Trac Issues: #13968

 Differential Revision: https://phabricator.haskell.org/D3789
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13968#comment:2>
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