vax-netbsd: Negative zero is only a thing IEEE 754.

So don't assume it universal in the signbit emulation.

For non-IEEE-754, negative zero is equal to the positive zero.

(Another matter is that signbit() should have been found
in the Configure scan; it does exist in the netbsd/vax.)

diff --git a/ext/POSIX/POSIX.xs b/ext/POSIX/POSIX.xs
index b573f5e..f8288e3 100644 (file)
--- a/ext/POSIX/POSIX.xs
+++ b/ext/POSIX/POSIX.xs
@@ -2636,7 +2636,12 @@ fpclassify(x)
 #ifdef Perl_signbit
            RETVAL = Perl_signbit(x);
 #else
 #ifdef Perl_signbit
            RETVAL = Perl_signbit(x);
 #else

-           RETVAL = (x < 0) || (x == -0.0);
+           RETVAL = (x < 0);
+#ifdef DOUBLE_IS_IEEE_FORMAT
+            if (x == -0.0) {
+              RETVAL = TRUE;
+            }
+#endif

 #endif
            break;
        }
 #endif
            break;
        }