[GHC] #13837: Calling qReifyInstances on out-of-scope Name leads to GHC internal error

[GHC]

#13837: Calling qReifyInstances on out-of-scope Name leads to GHC internal error
-------------------------------------+-------------------------------------
        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:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D3793
       Wiki Page:                    |
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Comment (by Ryan Scott <ryan.gl.scott@…>):

 In [changeset:"d6186496d414638aa66a677bb4e555dba376ec97/ghc"
 d6186496/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="d6186496d414638aa66a677bb4e555dba376ec97"
 Error eagerly after renaming failures in reifyInstances

 Summary:
 Previously, if `reifyInstances` failed to discover a `Name` during
 renaming, it would blindy charge into typechecking, at which point GHC
 would
 become very confused at the absence of that `Name` and throw an internal
 error.
 A simple workaround is to fail eagerly after renaming errors.

 Test Plan: make test TEST=T13837

 Reviewers: goldfire, austin, bgamari, simonpj

 Reviewed By: simonpj

 Subscribers: simonpj, rwbarton, thomie

 GHC Trac Issues: #13837

 Differential Revision: https://phabricator.haskell.org/D3793
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13837#comment:2>
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