-fvia-c doesn't work

[Simon Marlow]

On 29 September 2004 16:49, Malcolm Wallace wrote:

>>>     $ ghc-6.2.1 -c -fvia-c /tmp/ghcbug.hs
>>>     In file included from /usr/include/stdlib.h:414,               
>>>                      from
>>>                     
>>>     /usr/malcolm/local/lib/ghc-6.2.1/include/Stg.h:200, from
>>>     /tmp/ghc1723.hc:3: /usr/include/sys/types.h:190: conflicting
>>> types for `int8_t' stdint.h:33: previous declaration of `int8_t' 
>> 
>> Weirdly, -fvia-c works just fine today, with all versions of ghc
>> installed locally.  It must have been something in my local machine
>> config, even though I haven't changed anything since!
> 
> OK, after a couple more strange experiences, whereby -fvia-c sometimes
> worked and sometimes did not, depending on what directory I was in,
> I finally determined that the failure happened only when I had a file
> called "stdint.h" in the current directory.
> 
> So apparently, since a straight call of gcc does not display the same
> problem, the search path given to gcc by ghc somehow has . before
> the standard location of /usr/include?

Thanks for tracking this down.  For a workaround, you can say 

   ghc -I- ...

this causes ghc to pass '-I-' to gcc, which causes gcc to interpret all
the include paths as applying only to includes of the form #include
"...".  Includes of the form #include <...> will be searched for in the
system directories only.  Put the -I- after any other -I options on the
ghc command line.

I've made this change in GHC, but I probably won't merge it into 6.2.2
because it's only of those changes that could easily cause something
else to break, so we need plenty of testing.

Cheers,
	Simon