Disable bitwise operators

Some of them used to return wrong results, others just failed horribly. We're
disabling them alltogether, with a useful error message, until maybe someone
figures out how to make them DWIM.

2 files changed, 26 insertions, 1 deletions

diff --git a/dist/Math-BigRat/lib/Math/BigRat.pm b/dist/Math-BigRat/lib/Math/BigRat.pm
index 3508bf94f0..92cc59c2be 100644
--- a/dist/Math-BigRat/lib/Math/BigRat.pm
+++ b/dist/Math-BigRat/lib/Math/BigRat.pm
@@ -16,6 +16,7 @@ package Math::BigRat;
 # anythig older is untested, and unlikely to work
 use 5.006;
 use strict;
+use Carp ();
 
 use Math::BigFloat;
 use vars qw($VERSION @ISA $upgrade $downgrade
@@ -26,7 +27,16 @@ use vars qw($VERSION @ISA $upgrade $downgrade
 $VERSION = '0.26';
 $VERSION = eval $VERSION;
 
-use overload;			# inherit overload from Math::BigFloat
+# inherit overload from Math::BigFloat, but disable the bitwise ops that don't
+# make much sense for rationals unless they're truncated or something first
+
+use overload
+    map {
+	my $op = $_;
+	($op => sub {
+	    Carp::croak("bitwise operation $op not supported in Math::BigRat");
+	});
+    } qw(& | ^ ~ << >> &= |= ^= <<= >>=);
 
 BEGIN
   {
diff --git a/dist/Math-BigRat/t/bitwise.t b/dist/Math-BigRat/t/bitwise.t
new file mode 100644
index 0000000000..be9aa4ce38
--- /dev/null
+++ b/dist/Math-BigRat/t/bitwise.t
@@ -0,0 +1,15 @@
+use strict;
+use warnings;
+use Test::More tests => 22;
+
+use Math::BigRat;
+
+my $x = Math::BigRat->new('3/7');
+
+for my $op (qw(& | ^ << >> &= |= ^= <<= >>=)) {
+    ok !eval "my \$y = \$x $op 42; 1";
+    like $@, qr/^bitwise operation \Q$op\E not supported in Math::BigRat/;
+}
+
+ok !eval "my \$y = ~\$x; 1";
+like $@, qr/^bitwise operation ~ not supported in Math::BigRat/;