Re: BUG #2162: Same as bug #1679 - finite() - unresolved symbol

Thanks for your suggestion. It could have been the include files but I reco=
mpiled gcc on the system and it didn't change anything. Actually, I found t=
he solution when I tried to understand why configure detects a finite() fun=
ction on a system which does not have it.

First, I checked that there is no finite() function on my system: my libm.s=
l file is a symbolic link to libm.2, which does not contain this function. =
I don't know if it is the case for every HP-UX 11.11 system or if it is the=
 result of a patch (as there is another file in /usr/lib, named libm.1, whi=
ch contains the finite() function, probably for compatibility). And this sy=
mbol is not contained in any shared library under /usr (I checked them all).

When configure checks to see if we have finite(), it attempts to compile a =
small program containing 'dummy=3Dfinite(1.0)'. On my system, where I am us=
ing gcc 4.0.2, this small program is tested with a '-O2' flag, and the gcc =
optimizer is too smart ! It detects that we are writing to a dummy var, and=
 it removes the line ! You can verify it with 'gcc -S -O2' or with 'nm' app=
lied to the 'conftest' resulting executable file. After the call to finite(=
) has been removed, of course, the program compiles fine (it is empty now) =
and configure wrongly concludes that we have finite().

In order for the check to be done correctly, we have to provide a program t=
hat the compiler cannot optimize, ie where it cannot detect that the call i=
s useless, even if it is very very smart. Here is a patch with such a progr=
am. The fact of putting the call in a public function outside of main() for=
ces the compiler to keep it, as it could be referenced from another file at=
 link time.

$ diff configure.in configure.in.new
964c964
<    [int dummy=3Dfinite(1.0);],
---
>    [return 0; } int is_f(number) double number; { return finite(number); ]

After applying this patch on my system, everything works fine, HAVE_FINITE =
is not defined and float.c correctly switches to the isfinite() macro, defi=
ned in <math.h>.

Regards

Fran=E7ois