[GHC] #10543: MacOS: validate fails on \u

[GHC]

#10543: MacOS: validate fails on \u
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        Reporter:  trommler          |                   Owner:
            Type:  bug               |                  Status:  closed
        Priority:  normal            |               Milestone:
       Component:  Build System      |                 Version:  7.10.1
      Resolution:  invalid           |                Keywords:  cpp
Operating System:  MacOS X           |            Architecture:
 Type of failure:  Building GHC      |  Unknown/Multiple
  failed                             |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:  Phab:D1004
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Comment (by rodlogic):

 Replying to [comment:5 geoff]:
 > So, I was the one to add this line — overriding `-Wno-invalid-pp-token
 -Wno-unicode -Wno-trigraphs` — because these flags are not universally
 supported by clang. If anyone could help me understand this better, it
 would be appreciated.
 https://github.com/Homebrew/homebrew/issues/41777#issuecomment-122826887

 I am not that familiar with GHC's build system, so I can't answer that.
 Hopefully someone else can? Here is the question, inlined:
 {{{
 @rodlogic Is there a reason why the stage 0 bootstrap has to be built with
 -Werror? These warnings are pretty benign (indeed, more benign than the
 flags to suppress them). And what exactly is the significance of the \u in
 the source file, in this particular case? Support for unicode literals are
 not mandatory in POSIX in many places, and Mac OS X being a certified UNIX
 system, this is unlikely to change. The only way to reliably encode an
 arbitrary Unicode character in ASCII is is to use the octal sequences that
 comprise the glyph. Or, you could simply use the actual glyph, treating
 the source file as UTF-8, of course.

 But this seems particularly odd to me here, since the character that
 follows is t! So why is this needed here at all? What am I missing?
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10543#comment:6>
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