[GHC] #13271: GHC Panic With Injective Type Families

[GHC]

#13271: GHC Panic With Injective Type Families
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        Reporter:  wayofthepie   |                Owner:  (none)
            Type:  bug           |               Status:  new
        Priority:  normal        |            Milestone:
       Component:  Compiler      |              Version:  8.0.1
      Resolution:                |             Keywords:
Operating System:  Linux         |         Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown  |            Test Case:
      Blocked By:                |             Blocking:
 Related Tickets:                |  Differential Rev(s):
       Wiki Page:                |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"0c9d9dec0a924a4f34f4cff26d004143c028861a/ghc" 0c9d9de/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="0c9d9dec0a924a4f34f4cff26d004143c028861a"
 Remove panics for TcTyCon

 Previously TcTyCons were used only for knot-tying, but now they
 are also used after an error, to add a benign TyCon to the envt
 so we can carry on; see TyCon.makeRecoveryTyCon.  But since it
 is used in this way, subsequent declarations may see a TcTyCon
 (e.g. during injectivity checks) and should not have a heart attack
 as a result.

 See Note [TcTyCon] in TyCon.

 This fixes Trac #13271
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13271#comment:1>
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