C<undef> doesn't look like a number. See also:

Subject: Re: [perl #27606] undef "looks like" a number
Message-Id: <20040315221626.48061c67@r2d2>

p4raw-id: //depot/perl@22662

5 files changed, 7 insertions, 6 deletions

diff --git a/ext/List/Util/lib/List/Util.pm b/ext/List/Util/lib/List/Util.pm
index 77a52f6e1d..ff38fb4469 100644
--- a/ext/List/Util/lib/List/Util.pm
+++ b/ext/List/Util/lib/List/Util.pm
@@ -10,7 +10,7 @@ require Exporter;
 
 @ISA        = qw(Exporter);
 @EXPORT_OK  = qw(first min max minstr maxstr reduce sum shuffle);
-$VERSION    = "1.13";
+$VERSION    = "1.13_01";
 $XS_VERSION = $VERSION;
 $VERSION    = eval $VERSION;
 
diff --git a/ext/List/Util/lib/Scalar/Util.pm b/ext/List/Util/lib/Scalar/Util.pm
index c2aabcaa09..ad192a8a74 100644
--- a/ext/List/Util/lib/Scalar/Util.pm
+++ b/ext/List/Util/lib/Scalar/Util.pm
@@ -11,7 +11,7 @@ require List::Util; # List::Util loads the XS
 
 @ISA       = qw(Exporter);
 @EXPORT_OK = qw(blessed dualvar reftype weaken isweak tainted readonly openhandle refaddr isvstring looks_like_number set_prototype);
-$VERSION   = "1.13";
+$VERSION   = "1.13_01";
 $VERSION   = eval $VERSION;
 
 sub export_fail {
diff --git a/ext/List/Util/t/lln.t b/ext/List/Util/t/lln.t
index fe3ba4cb3a..80b0996c56 100644
--- a/ext/List/Util/t/lln.t
+++ b/ext/List/Util/t/lln.t
@@ -41,7 +41,7 @@ ok(!!looks_like_number("Inf"),	    $] >= 5.006001);
 ok(!!looks_like_number("Infinity"), $] >= 5.008);
 ok(!!looks_like_number("NaN"),	    $] >= 5.008);
 ok(!!looks_like_number("foo"),	    '');
-ok(!!looks_like_number(undef),	    1);
+ok(!!looks_like_number(undef),	    $] < 5.009002);
 # That's enough - we trust the perl core tests like t/base/num.t
 
 __END__
diff --git a/pp_ctl.c b/pp_ctl.c
index f0ac9fcb95..ec21e69bb9 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -1058,8 +1058,9 @@ PP(pp_flip)
 #define RANGE_IS_NUMERIC(left,right) ( \
 	SvNIOKp(left)  || (SvOK(left)  && !SvPOKp(left))  || \
 	SvNIOKp(right) || (SvOK(right) && !SvPOKp(right)) || \
-	(((!SvOK(left) && SvOK(right)) || (looks_like_number(left) && \
-	  SvPOKp(left) && *SvPVX(left) != '0')) && looks_like_number(right)))
+	(((!SvOK(left) && SvOK(right)) || ((!SvOK(left) || \
+          looks_like_number(left)) && SvPOKp(left) && *SvPVX(left) != '0')) \
+         && (!SvOK(right) || looks_like_number(right))))
 
 PP(pp_flop)
 {
diff --git a/sv.c b/sv.c
index c3a5a38f75..77ad8d0c1d 100644
--- a/sv.c
+++ b/sv.c
@@ -1910,7 +1910,7 @@ Perl_looks_like_number(pTHX_ SV *sv)
     else if (SvPOKp(sv))
 	sbegin = SvPV(sv, len);
     else
-	return 1; /* Historic.  Wrong?  */
+	return SvFLAGS(sv) & (SVf_NOK|SVp_NOK|SVf_IOK|SVp_IOK);
     return grok_number(sbegin, len, NULL);
 }