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-x assembler-with-cpp behavior different on different unixes.


Hello,

GHC (Haskell compiler) is using builtin gcc's cpp for its cpp
capability. The problem is a little bit different behaviour on
different platform which I observed. As one of GHC's testcases
completely unrelated to gcc's cpp we use:

{-# LANGUAGE CPP #-}
module T7145b ( A.Applicative(pure) ) where

import qualified Control.Applicative as A

pure :: ()
pure = ()


now, internally GHC calls GCC's cpp on this file with some -Is and
following options (-I <dir> removed for brevity):
/usr/bin/gcc -E -undef -traditional  '-D__GLASGOW_HASKELL__=709'
'-Dsolaris2_BUILD_OS=1' '-Di386_BUILD_ARCH=1' '-Dsolaris2_HOST_OS=1'
'-Di386_HOST_ARCH=1' -x assembler-with-cpp T7145b.hs -o
/tmp/ghc2662_0/ghc2662_1.hscpp

the problem is that produced code looks:

{-# LANGUAGE CPP #-}
module T7145b ( A.Applicative(pure) ) where

import qualified Control.Applicative as A

pure :: ()
pure = ()


so exact copy of the input file. Now, this is with Solaris 11.1
distributed GNU C 4.5.2. I've tested also 4.6.0, 4.7.1 and 4.8.2 built
by myself on the same platform and all those exhibit the same
behaviour.

Now, if I try the same on Ubuntu 14.04 LTS which provides GNU C 4.8.2,
then I get the expected output which contains

# 1 "T7145b.hs"
# 1 "<command-line>"
# 1 "/usr/include/stdc-predef.h" 1 3 4

# 17 "/usr/include/stdc-predef.h" 3 4
[ empty lines cut]
# 1 "<command-line>" 2
# 1 "T7145b.hs"
{-# LANGUAGE CPP #-}
module T7145b ( A.Applicative(pure) ) where

import qualified Control.Applicative as A

pure :: ()
pure = ()

Now my question is what exactly is expected behaviour and what not.
I'm mainly interested in this # 1 "7145b.hs" since we need it to get
the source file name right in following GHC emitted warning/error
messages. Is there any way how to enable those CPP marks even on
Solaris? Or is Ubuntu using some distro specific patch to enable this
behaviour and the behaviour itself is deprecated?

Thanks!

Karel


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