}
package main;
+use feature "err";
require './test.pl';
-plan( tests => 9 );
+plan( tests => 35 );
my($x);
$x='';
is($x // 0, '', ' // : left-hand operand defined but empty');
+like([] // 0, qr/^ARRAY/, ' // : left-hand operand a referece');
+
$x=1;
is(($x err 0), 1, ' err: left-hand operand defined');
$x='';
is(($x err 0), '', ' err: left-hand operand defined but empty');
+like(([] err 0), qr/^ARRAY/, ' err: left-hand operand a referece');
+
$x=undef;
$x //= 1;
is($x, 1, ' //=: left-hand operand undefined');
$x //= 0;
-is($x, 1, ' //=: left-hand operand defined');
+is($x, 1, '//=: left-hand operand defined');
$x = '';
$x //= 0;
-is($x, '', ' //=: left-hand operand defined but empty');
+is($x, '', '//=: left-hand operand defined but empty');
+
+@ARGV = (undef, 0, 3);
+is(shift // 7, 7, 'shift // ... works');
+is(shift() // 7, 0, 'shift() // ... works');
+is(shift @ARGV // 7, 3, 'shift @array // ... works');
+
+@ARGV = (3, 0, undef);
+is(pop // 7, 7, 'pop // ... works');
+is(pop() // 7, 0, 'pop() // ... works');
+is(pop @ARGV // 7, 3, 'pop @array // ... works');
+
+# Test that various syntaxes are allowed
+
+for (qw(getc pos readline readlink undef umask <> <FOO> <$foo> -f)) {
+ eval "sub { $_ // 0 }";
+ is($@, '', "$_ // ... compiles");
+}
+
+# Test for some ambiguous syntaxes
+
+eval q# sub f ($) { } f $x / 2; #;
+is( $@, '' );
+eval q# sub f ($):lvalue { $y } f $x /= 2; #;
+is( $@, '' );
+eval q# sub f ($) { } f $x /2; #;
+like( $@, qr/^Search pattern not terminated/ );
+eval q# sub { print $fh / 2 } #;
+is( $@, '' );
+eval q# sub { print $fh /2 } #;
+like( $@, qr/^Search pattern not terminated/ );
+
+# [perl #28123] Perl optimizes // away incorrectly
+
+is(0 // 2, 0, ' // : left-hand operand not optimized away');
+is('' // 2, '', ' // : left-hand operand not optimized away');
+is(undef // 2, 2, ' // : left-hand operand optimized away');