Assignment to a tainted variable was causing confusion if the source

value was an NV too large for an IV (bug #40708). Fix the confusion
by not promoting private flags to public flags in S_save_magic if
there are already public flags.

p4raw-id: //depot/perl@29669

1 files changed, 13 insertions, 1 deletions

diff --git a/t/op/taint.t b/t/op/taint.t
index 9e4bba2d70..533733276a 100755
--- a/t/op/taint.t
+++ b/t/op/taint.t
@@ -17,7 +17,7 @@ use Config;
 use File::Spec::Functions;
 
 BEGIN { require './test.pl'; }
-plan tests => 255;
+plan tests => 257;
 
 $| = 1;
 
@@ -1218,3 +1218,15 @@ SKIP:
     eval { sprintf("# %s\n", $TAINT . "foo") };
     ok(!$@, q/sprintf accepts other tainted args/);
 }
+
+{
+    # 40708
+    my $n  = 7e9;
+    8e9 - $n;
+
+    my $val = $n;
+    is ($val, '7000000000', 'Assignment to untainted variable');
+    $val = $TAINT;
+    $val = $n;
+    is ($val, '7000000000', 'Assignment to tainted variable');
+}