Extra tests for array/list slices in scalar context

Author: richardleach

t/op/array.t

@@ -6,7 +6,7 @@ BEGIN {
     set_up_inc('.', '../lib');
 }
 
-plan (195);
+plan (197);
 
 #
 # @foo, @bar, and @ary are also used from tie-stdarray after tie-ing them
@@ -707,3 +707,15 @@ fresh_perl_is('my @x;$x[0] = 1;shift @x;$x[22] = 1;$x[25] = 1;','',
   {}, 'unshifting and growing an array initializes trailing elements');
 
 "We're included by lib/Tie/Array/std.t so we need to return something true";
+
+# GH #23447 - ensure that future optimizations don't break behaviour
+{
+    my @x = "a" .. "d";
+    sub f {} 
+    my $y = @x[2, 3, f()];
+    is $y, 'd', 'Trailing empty list return in array slice in scalar context';
+
+    my @i;
+    $y = @x[2, 3, @i];
+    is $y, 'd', 'Empty array final element in array slice in scalar context';
+}

t/op/list.t

@@ -6,7 +6,7 @@ BEGIN {
     set_up_inc(qw(. ../lib));
 }
 
-plan( tests => 73 );
+plan( tests => 75 );
 
 @foo = (1, 2, 3, 4);
 cmp_ok($foo[0], '==', 1, 'first elem');
@@ -275,3 +275,14 @@ EOS
     my $e = "1"; $e = "(1,$e)" for 1..100_000; $e = "() = $e"; eval $e;
     is $@, "", "SEGV in Perl_list";
 }
+
+# GH #23447 - ensure that future optimizations don't break behaviour
+{
+    sub f {}
+    my $y = ("a" .. "d")[2, 3, f()];
+    is $y, 'd', 'Trailing empty list return in list slice in scalar context';
+
+    my @i;
+    $y = ("a" .. "d")[2, 3, @i];
+    is $y, 'd', 'Empty array final element in list slice in scalar context';
+}