From 0c61ae02299600bef03a658fcaefd0252964c4b8 Mon Sep 17 00:00:00 2001
From: Jarkko Hietaniemi <jhi@iki.fi>
Date: Fri, 21 Oct 2016 08:27:47 -0400
Subject: 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.)
---
 ext/POSIX/POSIX.xs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'ext')

diff --git a/ext/POSIX/POSIX.xs b/ext/POSIX/POSIX.xs
index b573f5e1f2..f8288e34a3 100644
--- a/ext/POSIX/POSIX.xs
+++ b/ext/POSIX/POSIX.xs
@@ -2636,7 +2636,12 @@ fpclassify(x)
 #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;
 	}
-- 
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