Some libm's support _LIB_VERSION (through math.h) to switch

behaviour.  Linux and Cygwin do, HP-UX and AIX don't. This probes
for _LIB_VERSION support and defines LIBM_LIB_VERSION if it does

p4raw-id: //depot/metaconfig@24216

diff --git a/U/perl/d_libm_lib_version.U b/U/perl/d_libm_lib_version.U
new file mode 100644 (file)
index 0000000..dc765ed
--- /dev/null
+++ b/U/perl/d_libm_lib_version.U
@@ -0,0 +1,50 @@
+?RCS: $Id$
+?RCS:
+?RCS: Copyright (c) 2005 H.Merijn Brand
+?RCS:
+?RCS: You may distribute under the terms of either the GNU General Public
+?RCS: License or the Artistic License, as specified in the README file.
+?RCS:
+?MAKE:d_libm_lib_version: Compile cat run rm i_math
+?MAKE: -pick add $@ %<
+?S:d_libm_lib_version:
+?S:    This variable conditionally defines the LIBM_LIB_VERSION symbol,
+?S:    which indicates to the C program that math.h defines _LIB_VERSION
+?S:    being available in libm
+?S:.
+?C:LIBM_LIB_VERSION:
+?C:    This symbol, if defined, indicates that libm exports _LIB_VERSION
+?C:    and that math.h defines the enum to manipulate it.
+?C:.
+?H:#$d_libm_lib_version LIBM_LIB_VERSION               /**/
+?H:.
+?T:foo
+?LINT:set d_libm_lib_version
+d_libm_lib_version="$undef"
+case $i_math in
+    $define)
+       : check to see if math.h defines _LIB_VERSION
+       echo " "
+       echo "Checking to see if your libm supports _LIB_VERSION..." >&4
+       $cat >try.c <<EOCP
+#include <unistd.h>
+#include <math.h>
+int main (int argc, char *argv[])
+{
+    printf ("%d\n", _LIB_VERSION);
+    return (0);
+    } /* main */
+EOCP
+       set try
+       if eval $compile; then
+           foo=`$run ./try`
+           echo "Yes, it does ($foo)" >&4
+           d_libm_lib_version="$define"
+       else
+           echo "No, it does not (probably harmless)\n" >&4
+           fi
+       $rm -f try.* try core core.try.*
+       ;;
+
+    esac
+