[okl4-developer] Cannot use the C library with C++?

[Alexandre Courbot]

Hello everybody,

I'm currently trying to port a C++ (well, C with classes actually)
written root server to OKL4 2.1.1-patch9. My problem is that it looks
like the C library does not like being parsed by the C++ compiler.
Consider the following example:

extern "C" {
#include <stdio.h>
}

int main()
{
        printf("Hello, world!\n");
        return 0;
}

After integrating it as a separate project and running the builder, I obtain:

$ ./tools/build.py machine=ia32_pc99 project=arc verbose_str=1
scons: Reading SConscript files ...
architecture ia32 is not yet supported by libcompat.
architecture ia32 is not yet supported by libcompat.
scons: done reading SConscript files.
scons: Building targets ...
/opt/okl/Linux-i386/stow/i686-unknown-linux-gnu/bin/i686-unknown-linux-gnu-g++
-Wall -Wredundant-decls -Wundef -Wpointer-arith -Wno-uninitialized
-Werror -O2 -nostdlib -nostdinc -fno-builtin -g -fno-exceptions
-fomit-frame-pointer -finline-limit=99999999 -DCONFIG_CPU_IA32_I686
-DCONFIG_CPU_IA32_I686 -DARCH_IA32 -DMACHINE_IA32_PC99 -DENDIAN_LITTLE
-DWORDSIZE_32 -DKENGE_L4_ROOTSERVER -DCONFIG_MAX_THREAD_BITS=10
-D__L4_ARCH__=ia32 -DL4_ARCH_IA32 -DCONFIG_USER_MUTEXES=1
-DTHREAD_SAFE -Ibuild/l4_rootserver/include
-Ibuild/l4_rootserver/object/arc/include arc/src/test2.cc -c -o
build/l4_rootserver/arc/object/src/test2.o
In file included from build/l4_rootserver/include/atomic_ops/atomic_ops.h:218,
                 from build/l4_rootserver/include/mutex/mutex.h:69,
                 from build/l4_rootserver/include/stdio.h:75,
                 from arc/src/test2.cc:2:
build/l4_rootserver/include/atomic_ops/arch/atomic_ops.h: In function
`okl4_atomic_plain_word_t
okl4_atomic_dec_return(okl4_atomic_word_t*)':
build/l4_rootserver/include/atomic_ops/arch/atomic_ops.h:324: warning:
passing negative value `-0x000000001' for converting 2 of
`okl4_atomic_plain_word_t okl4_atomic_add_return(okl4_atomic_word_t*,
okl4_atomic_plain_word_t)'
scons: *** [build/l4_rootserver/arc/object/src/test2.o] Error 1
scons: building terminated because of errors.

This is just a warning, but the builder does not let it go. Now if
only I knew how to fix it or how to disable the -Werror flag of the
compiler... :) Would someone have a pointer for this?

Thanks,
Alex.