Re: ac_check_funcs(getloadavg) with gcc 3.3

[Bob Friesenhahn]

The key is to not use C++ to execute these tests.  Use C while
checking for library functions.  Only set the language to C++ while
testing C++ related features.

Bob

On Mon, 19 Jan 2004, Hanspeter Roth wrote:

> Hello,
>
> I have AC_CHECK_FUNCS which looks for getloadavg(). This works with
> gcc 2.95 but fails on FreeBSD 5.2 where gcc has version 3.3.3.
> On FreeBSD 5.2 configure claims that getloadavg() is not available.
>
> configure.in:
>
> AC_INIT(configure.in)
> AC_PREREQ([2.50])
> dnl AC_LANG(C++)
> AC_LANG_CPLUSPLUS
> AC_CHECK_FUNCS(failed getloadavg sysctlbyname)
> AC_OUTPUT(Makefile)
>
> config.log:
>
> configure:1661: checking for getloadavg
> configure:1704: g++ -o conftest -g -O2   conftest.cc  >&5
> configure:1676: error: declaration of C function `char getloadavg()' conflicts
>    with
> /usr/include/stdlib.h:258: error: previous declaration `int 
> getloadavg(double*,
>    int)' here
> configure:1707: $? = 1
> configure: failed program was:
> #line 1666 "configure"
> #include "confdefs.h"
> /* System header to define __stub macros and hopefully few prototypes,
>     which can conflict with char getloadavg (); below.  */
> #include <assert.h>
> /* Override any gcc2 internal prototype to avoid an error.  */
> #ifdef __cplusplus
> extern "C"
> #endif
> /* We use char because int might match the return type of a gcc2
>    builtin and then its argument prototype would still apply.  */
> char getloadavg ();
> char (*f) ();
>
> #ifdef F77_DUMMY_MAIN
> #  ifdef __cplusplus
>      extern "C"
> #  endif
>    int F77_DUMMY_MAIN() { return 1; }
> #endif
> int
> main ()
> {
> /* The GNU C library defines this for functions which it implements
>     to always fail with ENOSYS.  Some functions are actually named
>     something starting with __ and the normal name is an alias.  */
> #if defined (__stub_getloadavg) || defined (__stub___getloadavg)
> choke me
> #else
> f = getloadavg;
> #endif
>
>   ;
>   return 0;
> }
> configure:1723: result: no
>
>
> How should this be solved?
> How can one make gcc 3.3.3 work with getloadavg()?
>
> -Hanspeter
>
>

======================================
Bob Friesenhahn
address@hidden
http://www.simplesystems.org/users/bfriesen