[GHC] #11407: -XTypeInType uses up all memory when used in data family instance

[GHC]

#11407: -XTypeInType uses up all memory when used in data family instance
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler (Type    |              Version:  8.0.1-rc1
  checker)                           |             Keywords:  TypeInType,
      Resolution:                    |  TypeFamilies
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:                    |
-------------------------------------+-------------------------------------

Comment (by Richard Eisenberg <eir@…>):

 In [changeset:"e9bf7bb5cc9fb3f87dd05111aa23da76b86a8967/ghc"
 e9bf7bb5/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="e9bf7bb5cc9fb3f87dd05111aa23da76b86a8967"
 Fix #11407.

 This removes the `defer_me` check that was in checkTauTvUpdate
 and uses only a type family check instead. The old defer_me check
 repeated work done by fast_check in occurCheckExpand.

 There is also some error message improvement, necessitated by
 the terrible error message that the test case produced, even when
 it didn't consume all of memory.

 test case: dependent/should_fail/T11407

 [skip ci]
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11407#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler