[GHC] #10623: Handling of ASCII encodings introduced in D898 breaks Unicode terminal detection

[GHC]

#10623: Handling of ASCII encodings introduced in D898 breaks Unicode terminal
detection
-------------------------------------+-------------------------------------
        Reporter:  bgamari           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:  7.10.3
       Component:  Compiler          |                 Version:  7.10.2-rc2
      Resolution:                    |                Keywords:
Operating System:  Windows           |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:  T8958a
      Blocked By:                    |                Blocking:
 Related Tickets:  #10298, #7695     |  Differential Revisions:
                                     |  Phab:D1059, Phab:D1085
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Comment (by rwbarton):

 It's not a regression, just a new test (I added it in
 dbe6dac96543f426297a59d8d16c3f5afacf42d4). The test uses `mkTextEncoding
 "ASCII"` which clearly (if you read `GHC.IO.Encoding.mkTextEncoding'`)
 won't work on Windows. It didn't work in the past either except between
 e28462de700240288519a016d0fe44d4360d9ffd and
 d69dfba4e27c4ec33459906fd87c9a56a371f510.

 Should we make it work, i.e., handle encodings in our hard-coded list as
 ASCII on Windows too? Personally I don't see why not.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10623#comment:11>
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