[GHC] #11518: Test TcCoercibleFail hangs with substitution sanity checks enabled

[GHC]

#11518: Test TcCoercibleFail hangs with substitution sanity checks enabled
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        Reporter:  niteria           |                Owner:  niteria
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by goldfire):

 Replying to [comment:11 niteria]:
 > It's always been 100: [0b7e538a09bc958474ec704063eaa08836e9270e].
 >

 No. Before that commit, `checkRecTc` allowed one unwrapping. The second
 failed (because the `TyCon` was in the `NameSet` nearby. But there's also
 a reference to the ticket that inspired the increase, which is helpful.

 I guess, in the end, we're never going to get this number correct. We
 could just have a flag for it, as suggested in the code there. Then, for
 this test, we use the flag.

 In the end, we're talking about a slowdown that affect only `DEBUG`
 compilers, yes? So I'm more worried about getting the test to pass before
 the end of the universe than in actually removing the exponential behavior
 -- especially given that the user's program indeed introduces the
 exponential behavior.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11518#comment:12>
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