Re: Suppressing warning AC_LANG_CONFTEST

[Eric Blake]

[please don't top-post on technical lists]

On 10/12/2010 02:34 PM, Ralph Castain wrote:
> Sorry for delay - was out. Since the code is rather long, I have simply 
> attached it here.
>
> Appreciate your help!

You're welcome!

> AC_DEFUN([EVENT_CHECK_ATTRIBUTES], [
>   AC_LANG(C)
>   AC_MSG_CHECKING(for __attribute__)
>
>   AC_CACHE_VAL(_cv___attribute__, [
>     AC_TRY_COMPILE(
>       [#include <stdlib.h>
>        /* Check for the longest available __attribute__ (since gcc-2.3) */
>        struct foo {
>            char a;
>            int x[2] __attribute__ ((__packed__));
>         };
>       ],

Bingo.  Just as the warning said, you are missing a call to 
AC_LANG_PROGRAM.  Also, you have insufficient quoting - to get an array 
x[2], rather than a variable name x2, you need more [] quoting.  You 
want to do:


AC_TRY_COMPILE(
  [AC_LANG_PROGRAM([[
    #include <stdlib.h>
    /* Check ... */
    struct foo {
      char a;
      int x[2] __attribute__ ((__packed__));
    };
  ]])],

and then on with the rest of your .m4 file.

>       [],
>       [_cv___attribute__=1],
>       [_cv___attribute__=0],

Also, while you're at it, it might be nice to rename your cache 
variables to have a useful prefix, rather than being in the nameless 
prefix namespace.

>     )
>
>     if test "$_cv___attribute__" = "1" ; then
>         AC_TRY_COMPILE(
>           [#include <stdlib.h>

Rinse and repeat - another missing AC_LANG_PROGRAM.

>   AC_DEFINE_UNQUOTED(HAVE_ATTRIBUTE, [$_cv___attribute__],
>                      [Whether your compiler has __attribute__ or not])

Get in the habit of proper m4 quoting:

AC_DEFINE_UNQUOTED([HAVE_ATTRIBUTE], [$_cv__attribute__], ...

> AC_DEFUN([IF_IFELSE], [
>     AC_COMPILE_IFELSE([#if !( $1 )
> #error "condition $1 not met"
> choke me
> #endif], [$2], [$3])])

Another case of missing AC_LANG_PROGRAM.

>             [AC_TRY_LINK([
>                     #include <stdio.h>

And another.

>             AC_CACHE_CHECK([if $CC supports -xldscope],
>                 [_cv_cc_xldscope],
>                 [AC_TRY_LINK([
>                         #include <stdio.h>

And another.

I think you can go from here on fixing this.

--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org