[GHC] #14113: Error message carets point at the wrong places in the presence of CPP macros

[GHC]

#14113: Error message carets point at the wrong places in the presence of CPP
macros
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Poor/confusing    |  Unknown/Multiple
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 Replying to [comment:3 Rufflewind]:
 > I think gcc has some internal magic with its cpp (and same for clang).
 If you compile using `gcc -E wat.c | gcc -x c -` you will run into exactly
 the same bug here.
 >
 > {{{
 > wat.c: In function ‘main’:
 > wat.c:4:12: warning: return makes integer from pointer without a cast
 [-Wint-conversion]
 >      FOO
 >             ^
 > }}}
 >
 > cpp simply does not provide ghc with adequate line information to
 determine the correct column.

 Urk, I was afraid of that.

 Well, if there isn't a reliable way to obtain this information, I suppose
 there isn't much we can do here. You mentioned that we could suppress the
 caret if CPP is involved, although I don't know if it's possible to
 reliably detect that. Alternatively, we could not do anything and close
 this as wontfix.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14113#comment:4>
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