gcc 4.3pre (20070824) vs. gmp.h: error: ‘std::FILE’ has not been declared

[Michael Abshoff]

Patrick Pelissier wrote:
> Hello,
>

Hello Patrick,

>   I have heard that g++ 4.3 has reduced a lot the dependencies between
> the system headers.

Okay, that matches my experience after compiling LinBox and a couple other
mathematical packages.

>   Before FILE was defined even if stdio.h was not included explicitly
> (See the output of g++ -E).
>  Now (4.3), it is not more defined, thought the error.
>

Great, esprecially with the "-E" option I forgot about.

>  I think the correct way to fix is:
>
> #if defined (__cplusplus)
> extern "C" {
> #ifdef _GMP_H_HAVE_FILE
> using std::FILE;
> #endif
> #endif
>
>  But I am not a C++ expert.
>

Does this stand a chance to get merged for a hypothetical 4.2.2? Torbjorn,
can you tell us if that is an acceptable solution or if you prefer
something else.

>   For checking of givaro inside the configure, as a work-around,
>   I suggest including cstdio explicitly before gmp.h.
>

I "fixed" it by including string.h in givaromm.C, but I am sure Clement
Pernet or somebody else out of the Givaro team will decide which way to
fix it best. I have attached your suggestion to the ticket in Sage trac
ticket.

> --
>  Sincerely,
>   Patrick Pélissier
>

Cheers,

Michael

> On 8/26/07, Michael Abshoff
> <Michael.Abshoff at fsmath.mathematik.uni-dortmund.de> wrote:
>> Hello,
>>
>> I ran into the following problem when compiling the following AC_CHECK
>> snippet with gcc 4.3pre (20070824 snapshot) when using gmp release
>> 4.2.1:
>>
>> [mabshoff at m940 src]$ cat gmp-version-check.c
>> #include <gmp.h>
>>
>> int main ()
>> {
>>   if (__GNU_MP_VERSION < 4)
>>     return -1;
>>   else
>>     return 0;
>> }
>>
>> [mabshoff at m940 src]# g++ -I ../../../../local/include/
>> gmp-version-check.c
>> -lgmp
>> In file included from gmp-version-check.c:1:
>> ../../../../local/include/gmp.h:515: error: 'std::FILE' has not been
>> declared
>>
>> (the code compiled fine with gcc, because the offending bit is ifdefd
>> with
>> __cplusplus). Removing the offending "using std::FILE" make the code in
>> question (which originated in the AC_CHECK of givaro) and givaro itself
>> (a
>> C++ library for arithmetic and algebraic computations) compile. But the
>> sample problem should show up in any C++ libary or code including gmp.h
>>
>> Now my questions:
>>
>> - Is that the recommended work-around or am I doing something wrong?
>> - I have to admit my ignorance: Why are we using "using std::FILE"
>> there?
>> Is it even needed for g++?
>>
>> Cheers,
>>
>> Michael
>>
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>