test the new flags behaviour, to prevent accidental breakage

Author: tonycoz

MANIFEST

@@ -5995,6 +5995,7 @@ t/op/sub.t			See if subroutines work
 t/op/sub_lval.t			See if lvalue subroutines work
 t/op/substr.t			See if substr works
 t/op/substr_thr.t		See if substr works in another thread
+t/op/svflags.t			See if POK is set as expected.
 t/op/svleak.pl			Test file for svleak.t
 t/op/svleak.t			See if stuff leaks SVs
 t/op/switch.t			See if switches (given/when) work

t/op/svflags.t

@@ -0,0 +1,30 @@
+#!./perl
+
+BEGIN {
+    chdir 't' if -d 't';
+    require './test.pl';
+    set_up_inc('../lib');
+    skip_all("need B, need full perl") if is_miniperl();
+}
+
+# Tests the new documented mechanism for determining the original type
+# of an SV.
+
+plan tests => 4;
+use strict;
+use B qw(svref_2object SVf_IOK SVf_NOK SVf_POK);
+
+my $x = 10;
+my $xobj = svref_2object(\$x);
+is($xobj->FLAGS & (SVf_IOK | SVf_POK), SVf_IOK, "correct base flags on IV");
+
+my $y = $x . "";
+
+is($xobj->FLAGS & (SVf_IOK | SVf_POK), SVf_IOK, "POK not set on IV used as string");
+
+$x = "10";
+is($xobj->FLAGS & (SVf_IOK | SVf_POK), SVf_POK, "correct base flags on PV");
+
+$y = $x + 10;
+
+is($xobj->FLAGS & (SVf_IOK | SVf_POK), (SVf_IOK | SVf_POK), "POK still set on PV used as number");