Configure check for geborken modfl(), inspired by

Subject: Re: [20010118.017] op/int.t failure
Message-Id: <200106051243.NAA15525@crypt.compulink.co.uk>

p4raw-id: //depot/perl@10455

diff --git a/Configure b/Configure
index 0e86e14..7c35f33 100755 (executable)
--- a/Configure
+++ b/Configure
@@ -20,7 +20,7 @@
 
 # $Id: Head.U,v 3.0.1.9 1997/02/28 15:02:09 ram Exp $
 #
-# Generated on Tue Jun  5 04:50:23 EET DST 2001 [metaconfig 3.0 PL70]
+# Generated on Thu Jun  7 00:46:23 EET DST 2001 [metaconfig 3.0 PL70]
 # (with additional metaconfig patches by perlbug@perl.org)
 
 cat >c1$$ <<EOF
@@ -10476,6 +10476,52 @@ esac
 set modfl d_modfl
 eval $inlibc
 
+case "$d_longdbl$d_modfl" in
+$define$define)
+       $cat <<EOM
+Checking to see whether your modfl() is okay for large values...
+EOM
+$cat >try.c <<EOCP
+#include <math.h> 
+#include <stdio.h>
+int main() {
+    long double nv = 4294967303.15;
+    long double v, w;
+    v = modfl(nv, &w);         
+#ifdef __GLIBC__
+    printf("glibc");
+#endif
+    printf(" %"$sPRIfldbl" %"$sPRIfldbl" %"$sPRIfldbl"\n", nv, v, w);
+    return 0;
+}
+EOCP
+       set try
+       if eval $compile; then
+               foo=`./try`
+               case "$foo" in
+               *" 4294967303.150000 1.150000 4294967302.000000")
+                       echo >&4 "Your modfl() is broken for large values."
+                       d_modfl="$undef"
+                       case "$foo" in
+                       glibc)  echo >&4 "You should upgrade your glibc to at least 2.2.2 to get a fixed modfl()."
+                       ;;
+                       esac
+                       ;;
+               *" 4294967303.150000 0.150000 4294967303.000000")
+                       echo >&4 "Your modfl() seems okay for large values."
+                       ;;
+               *)      echo >&4 "I don't understand your modfl() at all."
+                       d_modfl="$undef"
+                       ;;
+               esac
+               $rm -f try.* try core core.try.*
+       else
+               echo "I cannot figure out whether your modfl() is okay, assuming it isn't."
+               d_modfl="$undef"
+       fi
+       ;;
+esac
+
 : see if mprotect exists
 set mprotect d_mprotect
 eval $inlibc