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Blitz Support : |
From: Zane Dodson (zdodson_at_[hidden])
Date: 2005-05-18 13:42:13
Hello Julian,
On Wed, May 18, 2005 at 10:41:09AM -0700, Julian Cummings wrote:
| Hi Derrick,
|
| I don't think the problem is that the configure script sees different
| files than the actual code. The real problem here is that the line
|
| #ifdef isnan
|
| does not work as expected. This would detect if isnan were defined to
| be a value like 1 or something. But when it is defined to be a macro
| function, then it is not expanded unless it is followed by an argument
| list. Unfortunately, doing something like
|
| #ifdef isnan(x)
|
| does not work either. I've tried some tricks using concatenation, but
| none of them work quite like I had hoped. I don't think just adding
| another macro will solve this problem. We need to figure out how to get
| the preprocessor to select the simple "return isnan(a);" line when isnan
| is a macro function. There must be a way to do this...
<snip>
Here is what I have used in the past.
dnl === Checks for specific functions
dnl ==== isnan ====
dnl ===== Could be a macro or a function. C99 requires a macro.
AC_LANG_PUSH([C])
AC_CHECK_FUNCS([isnan])
if test $ac_cv_func_isnan = no; then
# isnan not in default libraries; try as a macro.
AC_MSG_RESULT([for isnan macro])
AC_TRY_LINK([#include <math.h>],
[{int tmp = isnan(0);}],
[ac_cv_func_isnan=yes],
[ac_cv_func_isnan=no])
if test $ac_cv_func_isnan = yes; then
AC_MSG_RESULT([yes])
AC_DEFINE([HAVE_ISNAN])
else
AC_MSG_RESULT([no])
fi
fi
Kindest regards,
-- Zane Dodson