[GHC] #16068: Unsaturated type synonyms as arguments work in 8.6.3 but not HEAD

[GHC]

#16068: Unsaturated type synonyms as arguments work in 8.6.3 but not HEAD
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        Reporter:                    |                Owner:  (none)
  quasicomputational                 |
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.7
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         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 simonpj):

 Yes -- you should really need `LiberalTypeSynonyms` to accept this; and
 it's a bug in 8.6 that it doesn't check for that.

 Perhaps it'd be worth adding to the 8.8 migration guide (Ben)?

 There are a number of other tickets on `LiberalTypeSynonyms` that Ryan is
 working on: eg #16059, #16013 I think.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16068#comment:1>
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