[patch, fortran] PR18428: use libcpp for preprocessing (review of C/C++ and fortran maintainers needed)

[FX]

> I don't have the code around, but IIRC: the return value sets a
> no_backend (or similar) variable in the driver. If 'false' is returned
> the backend is initialized, otherwise not. In the latter case,
> something somewhere crashed and gave an ICE.

OK, fine with me for now :)

>> I don't think we want to define __STDC_HOSTED__. On the other  
>> hand, does
>> your patch still define the CPU, OS and OBJFMT builtins? (macros
>> TARGET_CPU_CPP_BUILTINS, TARGET_OS_CPP_BUILTINS and
>> TARGET_OBJFMT_CPP_BUILTINS) I think we should. Other macros that  
>> we used to
>> emit and I think we will now miss include: __VERSION__,
>> [...] macros (which are I think potentially useful).
>
> None of these are set. I went with the docs and only implemented those
> mentioned. If we want all macros defined by gcc, we probably can
> re-use their code.

Yes, that sounds like a good thing to do. Parts of our testsuite and  
my own personal codes use CPU and OS macros for conditional  
compilation, and I think they're good to have around.

>>> +  /* Supply enough spaces to put this token in its original column,
>>> +     one space per column greater than 2, since  
>>> scan_translation_unit
>>> +     will provide a space if PREV_WHITE.  Don't bother trying to
>>> +     reconstruct tabs; we can't get it right in general, and  
>>> nothing
>>> +     ought to care.  Some things do care; the fault lies with  
>>> them.  */
>>
>>  Can you expand a bit more here? What kind of thing will change or  
>> be broken
>> exactly?
>
> Errr, please ask the original author. I think, this was copied
> verbatim from c-ppoutput.c :)

Yep, I thought that was the case... what I'm worried is that Fortran  
isn't C, and tabs are special in Fortran. If you get some time to  
check that basic things still work (accepted or rejected correctly),  
that would be enough. Maybe it's already covered by the testsuite,  
actually...

FX


-- 
François-Xavier Coudert
http://www.homepages.ucl.ac.uk/~uccafco/