[GHC] #12213: In Python testsuite, setting stdout to unbuffered causes us to switch to ascii output locale

[GHC]

#12213: In Python testsuite, setting stdout to unbuffered causes us to switch to
ascii output locale
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        Reporter:  ezyang            |                Owner:  thomie
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Test Suite        |              Version:  8.0.1
      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 Thomas Miedema <thomasmiedema@…>):

 In [changeset:"e8d62711e6cbc3065ee5e6f6a654667f02a0bcd1/ghc" e8d6271/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="e8d62711e6cbc3065ee5e6f6a654667f02a0bcd1"
 Testsuite: do not depend on sys.stdout.encoding

 The cause of #12213 is in dump_stdout and dump_stderr:

       print(read_no_crs(<filename>))

 Commit 6f6f515401a29d26eaa5daae308b8e700abd4c04 changed read_no_crs to
 return a unicode string. Printing a unicode strings works fine as long
 as sys.stdout.encoding is 'UTF-8'.

 There are two reasons why sys.stdout.encoding might not be 'UTF-8'.

 * When output is going to a file, sys.stdout and sys.stdout do not respect
   the locale:

   $ LC_ALL=en_US.utf8 python -c 'import sys; print(sys.stderr.encoding)'
   UTF-8
   $ LC_ALL=en_US.utf8 python -c 'import sys; print(sys.stderr.encoding)'
 2>/dev/null
   None

 * When output is going to the terminal, explicitly reopening sys.stdout
 has
   the side-effect of changing sys.stdout.encoding from 'UTF-8' to 'None'.

       sys.stdout = os.fdopen(sys.__stdout__.fileno(), "w", 0)

   We currently do this to set a buffersize of 0 (the actual
   buffersize used is irrelevant for the sys.stdout.encoding problem).

 Solution: fix dump_stdout and dump_stderr to not use read_no_crs.
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12213#comment:5>
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