+#!./perl
+
+#
+# Verify which OP= operators warn if their targets are undefined.
+# Based on redef.t, contributed by Graham Barr <Graham.Barr@tiuk.ti.com>
+# -- Robin Barker <rmb@cise.npl.co.uk>
+#
+
+BEGIN {
+ chdir 't' if -d 't';
+ @INC = '../lib';
+}
+
+use strict;
+use warnings;
+
+my $warn = "";
+$SIG{q(__WARN__)} = sub { print $warn; $warn .= join("",@_) };
+
+sub ok { print $_[1] ? "ok " : "not ok ", $_[0], "\n"; }
+
+sub uninitialized { $warn =~ s/Use of uninitialized value[^\n]+\n//s; }
+
+print "1..32\n";
+
+{ my $x; $x ++; ok 1, ! uninitialized; }
+{ my $x; $x --; ok 2, ! uninitialized; }
+{ my $x; ++ $x; ok 3, ! uninitialized; }
+{ my $x; -- $x; ok 4, ! uninitialized; }
+
+{ my $x; $x **= 1; ok 5, uninitialized; }
+
+{ my $x; $x += 1; ok 6, ! uninitialized; }
+{ my $x; $x -= 1; ok 7, ! uninitialized; }
+
+{ my $x; $x .= 1; ok 8, ! uninitialized; }
+
+{ my $x; $x *= 1; ok 9, uninitialized; }
+{ my $x; $x /= 1; ok 10, uninitialized; }
+{ my $x; $x %= 1; ok 11, uninitialized; }
+
+{ my $x; $x x= 1; ok 12, uninitialized; }
+
+{ my $x; $x &= 1; ok 13, uninitialized; }
+{ my $x; $x |= 1; ok 14, ! uninitialized; }
+{ my $x; $x ^= 1; ok 15, ! uninitialized; }
+
+{ my $x; $x &&= 1; ok 16, ! uninitialized; }
+{ my $x; $x ||= 1; ok 17, ! uninitialized; }
+
+{ my $x; $x <<= 1; ok 18, uninitialized; }
+{ my $x; $x >>= 1; ok 19, uninitialized; }
+
+{ my $x; $x &= "x"; ok 20, uninitialized; }
+{ my $x; $x |= "x"; ok 21, ! uninitialized; }
+{ my $x; $x ^= "x"; ok 22, ! uninitialized; }
+
+{ use integer; my $x; $x += 1; ok 23, ! uninitialized; }
+{ use integer; my $x; $x -= 1; ok 24, ! uninitialized; }
+
+{ use integer; my $x; $x *= 1; ok 25, uninitialized; }
+{ use integer; my $x; $x /= 1; ok 26, uninitialized; }
+{ use integer; my $x; $x %= 1; ok 27, uninitialized; }
+
+{ use integer; my $x; $x ++; ok 28, ! uninitialized; }
+{ use integer; my $x; $x --; ok 29, ! uninitialized; }
+{ use integer; my $x; ++ $x; ok 30, ! uninitialized; }
+{ use integer; my $x; -- $x; ok 31, ! uninitialized; }
+
+ok 32, $warn eq '';
+
+# If we got any errors that we were not expecting, then print them
+print map "#$_\n", split /\n/, $warn if length $warn;