void -> char cast

[Marc Glisse]

On Sun, 12 Jan 2014, Conor Williams wrote:

> g++ m9.7.7.C -std=c++0x -I/home/will51/LPS!/lpsb/gmp-5.1.3
> -L/home/will51/lib -o 9.7.7++ -I/home/will51/include -DHAVE_STDARG -O2
> -pedantic -fomit-frame-pointer -m64 -mtune=k8 -march=k8  -lexpr -lgmp
> -D_NUMBER_LOGGING_
> /home/will51/tmp/cceXyum4.o: In function `main':
> m9.7.7.C:(.text+0x283): undefined reference to `mpz_expr(__mpz_struct*,
> int, char const*, ...)'
> m9.7.7.C:(.text+0x418): undefined reference to `mpz_expr(__mpz_struct*,
> int, char const*, ...)'
> m9.7.7.C:(.text+0x447): undefined reference to `mpz_expr(__mpz_struct*,
> int, char const*, ...)'
> m9.7.7.C:(.text+0x583): undefined reference to `mpz_expr(__mpz_struct*,
> int, char const*, ...)'
> m9.7.7.C:(.text+0x830): undefined reference to `mpz_expr(__mpz_struct*,
> int, char const*, ...)'
> collect2: ld returned 1 exit status
> make: *** [all] Error 1
>
> when i re-link with g++ compied libs there are no errors...
> this is with and with the 'exten "C"...'

Ah, now I understand what you are doing (it would have helped to say more 
from the beginning). You are compiling the demo libexpr, then using it in 
a C++ program. But the header expr.h hasn't been made C++-safe. Using 
Steve's extern "C" advice on the file expr.h (not gmp.h) would indeed have 
solved this issue for you.

We don't promise much for the demo, but I'll add extern "C" in the header, 
that's harmless.

-- 
Marc Glisse